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Bill Vatter
Posted on Thursday, 06 September, 2001 - 14:40:   Edit PostDelete PostView Post/Check IP

I have an early post war six cylinder engine that came from Silver Wraith WFC10, a car that died from sitting outside too long with the farm creatures living in it. The car has been disassembled for parts and is no more.

The engine has no number stamped on the lug where the number should be stamped. However, there is a number cast into the left front side of the crankcase low down just above and forward of the lug where there should be an engine number. This number reads "RE 9421" in 5/8 inch high raised letters and numerals, and below this the letters "FF." I have not seen such a cast-on number like this on other early post-war six engines.

The engine has the full-flow oil filter, but not the conversion that would have the oil pipes connected to the relief valve body, which would have been correct for engines installed in all chassis before the WME series. Instead it is exactly like the later 4 1/2 liter blocks and the few that were cast with provisions for full-flow filters but delivered with the bypass filter. That was the WME series Silver Wraiths and I believe the KL, LJ, and LH series MK VI Bentleys.

The engine has the 4 1/4 liter cylinder head, the early-type water pump pully, a two-wire dynamo and there are no reinforcing lugs between the block and the clutch cover, all of which would be correct for a WFC series chassis. I think these parts are probably the original components that came with the car, but the engine block certainly is not. The engine has, however, had the later type water outlet that has a water thermostat as with a MK VI Bentley. (Early Silver Wraith engines through the WDC series at least and maybe later had no water thermostat, relying on the movable radiator shutters only for temperature regulation.) Almost every engine today has the water thermostat as well as the radiator calorstat, which was standard to have both on the later cars, but I don't know when it became standard. I think most of the early cars have been converted by now.

I suspect this is a factory replacement engine, but I would like to find out for sure, and I would like to know about when it was manufactured. I have not removed the cylinder head, and I do not know if it has been re-bored or if the crankshaft journals are still standard size.

In the US, conventional wisdom in reboring these engines is to bore out the bricrome inserts and install full-length sleeves. I have read that Rolls-Royce provided a full-length sleeve (RR part number RH7900) (Illustrated Rolls-Royce Bentley Buyers Guide by Paul Woudenberg revised edition). The bricrome insert was used through all of the 4 1/2 liter engines, but was not used in the 4.9 liter engines (Clouds). Does anyone know if the factory replacement 4 1/4 liter engines produced after the start of Cloud production, when the factory apparently was aware the bricrome insert was not such a good thing, had bricrome inserts or the full length insert?

Can anyone shed light on exactly what is this engine?
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Norman Geeson
Posted on Saturday, 08 September, 2001 - 06:21:   Edit PostDelete PostView Post/Check IP


The first part of the mystery is easy. RE9421 was the actual crankcase part number.The letters FF stand for Farington Foundry, Leyland, Lancashire, England, Faringdon was the foundry arm of Leyland Motors. If you have seen a Leyland truck, its engine block was cast in the same foundry.

Having no engine number would generally indicate to me that a replacement block has been fitted at some stage. Many of these blocks suffered frost damage, sometimes because the owner took the handbook at face valve and thought he /she could drain off all the coolant. Much of the water was retained in the cooling silt and the blocks froze.

It is not impossible that a R-R replacement engine has been fitted, but doubtful It was normal practice to renumber the engines exactly as the one being replaced,the chassis card being notated accordingly with not only the new number but also the engine number before it was rebuilt.The exception was when some main agents reconditioned engines and stamped a suffix R behind the engine number.

Blocks were cast from around March 1950 to take full flow filters equating to Bentleys from the H series onwards and I believe all these engines actually went through engine test with full flow filters fitted.

The earlier blocks did not seem to have FF cast in to the casting and R-R certainly used at least another foundry on the Military B60 engines. It was normal FF practice to cast the letters FF somewhere on the casting and this is quite normal to see on the 4.5 blocks.I suspect this was a block manufactured around 1953 as a replacement.

The R-R sleeve RH7900 is listed as an oversize O/D sleeve for a 4.5 engine.Various liner manufacturers do list sleeves/ liners for these 4.25 engines and in fact R-R had these manufactured at least up to 1990 if not later.I do not have the part number to hand at the moment unfortunately.

It is not wise to obtain liners for these engines before boring out the old liners and sizing the block.Even from new many engines had oversize O/D liners and many later 4.5 engines have two oversize liners out of the six.

It is not only U.S but good engineering practice to fit full length liners, anyone contemplating fitting original two piece liners is not going far down the road! Assuming they also fit pistons with the correct clearance to suit modern day engine operation.Natives to this site will be glad to hear that the best pistons for these engines are not manufactured in U.S.A or England for that matter, but in Australia.

4.5 ltr replacement factory engines were still being fitted with two piece liners in 1957 and there does not appear to be a clean break point. I would therefore presume the 4.25 reconditioning followed the same pattern.

There is no need to remove the head to see if the engine has two piece liners.Hire a borescope and look down the spark plug holes, much cheaper than removing the head.Or try placing a very small bulb down the bore and sighting with a fine cardboard tube, in other words make up your own illuminated telescope.

Two piece sleeves/liners in the above context means either the factory fit top brichrome with parent bore below or the brichrome with a second liner below.

The factory was well aware that the brichrome liners were not such a good thing at least as early as 1952 when some engines were tried with full length liners to test.

I hope the data may help.It would be difficult to prove the engine is ex-factory reconditioned with out an engine number and probably in truth irrelavent considering the time which has past since it may have been R-R reconditioned.

Best Regards


Norman Geeson
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Bill Vatter
Posted on Saturday, 29 September, 2001 - 12:53:   Edit PostDelete PostView Post/Check IP

Many thanks to Norman for this information.
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Norman Geeson (
Posted on Friday, 21 June, 2002 - 01:17:   Edit PostDelete PostView Post/Check IP


Whilst researching for a forthcoming article on the 4.25 / 4.5 ltr blocks it was necessary for me to identify the RE9421 Block.

This is definately an "intermediate" 4.5 ltr block but originally fitted with the small top cuff liner and bored 4.25 ltr.It was used in the MKVI Bentley versions from around the H series to the end of the LH series.Original tested on R-R test beds with the full flow filter and then fitted with the bye pass oil filter for production fitting into the chassis. Besides checking the detail I have physically checked two original blocks in KL and LH series Bentleys which both have the RE 9421 blocks.I trust this later checked out data may help.
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Bill Vatter (
Posted on Friday, 21 June, 2002 - 10:59:   Edit PostDelete PostView Post/Check IP


Thanks for this information. Your previous posting information was confirmed when I took the head off in preparation for a rebuild. The engine was idle for so long and was quite full of sludge, so I did not consider trying to use it as-is. On removing the cylinder head (not an easy task) I found the bores were standard, but the crank ground undersize .020 inch on both rod and main journals. Your previous supposition that the block needed replacing due to some unfortunate incident seems most likely, and while they had it all apart, they reconditioned the crank as well. That could have been required if the old block had cracked and glycol got into the oil. As you predicted, the block has the short liners. Too bad, I was looking forward to just boring it oversize and fitting new pistons, but now I will need to get the old short liners out and sleeve it back to standard for an additional machine shop charge. Nothing seems to be inexpensive when I go to work on an old RR car.

For those interested, an article appears in the latest FL magazine (RROC US) on removing difficult cylinder heads.

Norman, you say that RE9421 is a 4.5 ltr. block bored 4.25. In the case of this particular engine, that is not all that is different from the 4.5 liter block. In this engine the cylinder head studs are in the 4.25 Ltr. configuration and not that of the 4.5 Ltr. blocks, and of course the 4.25 cylinder head was retained. I would suppose it is probably exactly the same as the blocks on the very late 4.25 Bentleys and SWs as well as the Silver Dawns, (probably all of the SBD series which I think correspond approximately to the K and L series Bentleys). I suppose you could also say all of these are 4.5 Ltr. blocks with the studs put in for the 4.25 cylinder heads.

Where will your article about these engines appear? I would be interested to see it.
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N.W. Geeson (
Posted on Sunday, 30 June, 2002 - 06:15:   Edit PostDelete PostView Post/Check IP

The confusion between 4.5 ltr blocks appears this way.The original 4.25 ltr blocks had individual coolant passageways between each parent cylinder block bore. In late 1949 R-R introduced what THEY called the 4.5 ltr block into production,at least later part number RE 9421. This had the front and rear three parent block cylinder bores cast in siamese fashion with coolant passages around No1 and No 6 cylinder and also between cylinder 3 and 4 only. In addition it was adapted for full flow oil filterage and had a different brass coolant gallery. The cylinder head stud pattern was as for 4.25 ltr and of course it was bored at 3.5 inch for 4.25 ltr with top cuff liners.This block also did not have the oil gallery tapped at the rear as was the case with the proper 4.5 ltr block. However, events seem to have overtaken the situation and a true 4.5 ltr block was later cast for the introduction of the larger engine. This proper 4.5 ltr block as you state had a different head stud pattern, full flow oil filter etc. None of the blocks received full liners until the introduction of the 4.9 block.
As I have said, R-R themselves used the term 4.5 ltr blocks which refered to the last bored 4.25 block. It is probable that they intended to bore out this post 1950 block to 4.5 ltr for the R type Continental initially.This block will in fact bore out to 4.5 ltr, however many suffered both bore break through in production and porosity in the lower bore.The larger bottom liner was inroduced to combat this porosity on production from 1949, later the bottom liner was used in service to reclaim lower scored bores. Many alterations were taking place at the time including many tests on cylinder head gaskets and it is probable the stud pitch and of course the casting was altered to accomadate these other issues together with alterations to prevent cylinder bore core casting slippage.

The article to which I refered is some 25000 words with 14 figs / pictures. It covers the general block history, liners, pistons, boring, cooling, high speed fans, leaks and tappets to name some.At the present time it should be appearing shortly in the RREC bulletin. If you wish to have a copy direct and are willing to take the down load time and accept attachments, all NORTON checked, please e-mail me direct.

Best Regards

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Bill Vatter (
Posted on Sunday, 30 June, 2002 - 10:58:   Edit PostDelete PostView Post/Check IP


The whole reason I got into this trail of cylinder block details, is that engines with the short liners are notorious for piston failures, and I was hoping that this different block would have full-length liners or sleeves as in the Clouds. My thinking was that if RR recognized a full-length liner or sleeve was better, they might have started fitting it to replacement blocks and engines. At least that is what I had hoped.

Do you have any insight into the cause of piston rings breaking in the engines that have the short liner? I have heard many people state it is due the rings bumping over the interface between the cast iron and the hard liner, and its true there is a variation in the bore on worn engines of a thousandth of an inch or so at this place. In severe cases the top ring then gets hammered up to the top of the piston, and pieces of it break out into the combustion chamber creating a tremendous knock when it gets between the piston and the cylinder head that lasts until the broken piece makes its way out the exhaust valve. The affected cylinder ceases to work from excess oil and low compression, and a comprehensive overhaul for significant money is the prescribed medicine. I am not sure this failure is because of the bump and resultant flexing of the ring. It seems that if this were the cause, it would be a fatigue failure, but in engines that have no liner at all (before WCB30, there is greater total flexing of the rings due to the larger wear to the bore at the very top, yet these other engines don't break piston rings nearly as often.

Paul Woudenberg states in his book "Illustrated Rolls-Royce Bentley Buyers Guide," the broken piston rings are caused by another phenomenon: He states, "...the liner would shrink, interrupting heat flow to the block. This resulted in overheating of the piston, broken rings, and occasional piston failure." In my experience, overheating is the number one cause of broken rings with conventional cylinder bores. My understanding is this happens when the rings expand from intense heat to completely close the ring end gap followed by extreme stress to the ring when it cannot expand further, resulting in breakage.

Conventional wisdom amongst individuals I associate with is to bore out the liner and fit a full-length cast-iron sleeve (not a hard liner) but no one seems to know why not a hard liner. One person says, you can't get the rings to seat against a hard liner, but this does not make sense to me. Of course, with the use of modern oils, cast iron will work fine, cylinder wear is not the problem it was when the very first post-war engines were made, and the liner vs. sleeve debate of accademic interest only. I am curious if RR ever confirmed the hard liner had a lower coeficient of thermal expansion resulting in the interruption of heat flow to the block as Woudenberg states. Usually when RR fixed a known defect they were pretty quiet about it.

Also, the pistons that I have seen failed as described above are almost always cylinder #4, which is a curious thing.

Perhaps if we knew exactly what was happening, we could do something to stop it short of boring and resleeving the block.

Have any insight?
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Jim Bettison (
Posted on Monday, 01 July, 2002 - 21:52:   Edit PostDelete PostView Post/Check IP

Does the offer you made Bill for an early copy of your article extend to others? I would very much like to have a copy, as your summary indicated that you will be dealing with some matters that are presently of much interest to us ...
If you can give me your e-mail and/or fax adress by fax to +61 8 8370 9655 (that's Australia) I'll fax back mine - assuming that we neither of us want to make these addresses public.
I must admit that I think that I have your address through a dialogue we had last year, but have to admit I can't find it.
Jim Bettison.
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Norman Geeson (
Posted on Wednesday, 03 July, 2002 - 06:53:   Edit PostDelete PostView Post/Check IP

Bill and Jim

As you will have noticed by now the download time for the article and text is quite extended.Anyone really wishing for and wanting a copy to assist them in a current engine overhaul can contact me at e-mail CC6@lineone.net. I would however plead that members do not make such a request unless they are involved in a current overhaul and really need the data. I am fairly certain the article will be printed for all to see quite soon.Due to limited space I can only list here a few points in relation to Bill's last post.

The earlier chrome bore 4.25 engines do not generally break piston rings as frequently as the later types with the top cuff liners. All the engines before the liners were introduced had high speed water pumps and fans for all markets, the cylinder blocks had water passages between each parent block bore and of course the rings did not have to contend with any ridge between the parent bore and liner. Of course the earlier lined engines had these advantages except of course the liner ridge, the later lined engines suffered the cooking problems and the ridge. This ridge was present during initial production to some degree and is recorded as such in the original archive R-R internal memo's.
The liners can be said to shrink, probably a better term would be to say they quarrel with the block casting. The area is subject to extreme temperatures across the top block deck bridge piece between the exhaust valve seat and the bore. Distortion takes place, due to localised overheating and expansion and contractions cause liner quarreling resulting in a gap between the cuff liner and bore.This in turn enables combustion products to be forced between the faces providing insulation of the cooling effect, just what is not wanted.In many cases the cuff liners are loose when cold and almost certainly when the engine is hot, in addition they are mis-shaped.The result of the ridge wear, which itself is a result of different metals, together with distortion and shrinkage of the liner severely reduces ring life.What is also not realised is that once liner / bore quarreling has taken place the liners tilt as the piston goes over TDC.These cuff liners are only 0.062 thick and when full liners were introduced they followed into production with the same thickness although they were originally intended to be 0.93 thick. The only reason the thickness was reduced was to avoid boring through the water jacket on blocks which had casting core slippage problems.

A little thought, shows that if either the cuff liners or the full liners are overbored the result is no more than a thin tin can, and just as useful. Compounding this situation is the water flow, with the exception of cars destined for Australia or Switzerland, cars from the mid Bentley GT series cars ( and equivelant R-R cars)
had low speed water pumps and fans.By 1956 R-R had recommended that in all cases of overheating, world wide, that the high speed fan / pump should be fitted.Once again making the situation worse was the gradual fitting of even higher rated thermostats and these cars do not take kindly to thermostats in Summer months higher rated than 73C

The only real answer is a clean block, mechanically cleaned, with full liners and with the proviso that the boring is done with the water pump adapter in place and the honing is done with the head studs in place. If completed with the fitment of an original low rated thermostat of 72C/73C and manadatory conversion to a high speed fan/pump coupled with opening out of the front shutter angles. Then the engine should last a true lifetime.
Very often regular block flushing is ignored and even full linered engines up to and including Cloud 1's suffer from piston scuffing/ seizure.In these cases the full liner pulls away from the parent block bore and waves are formed down the bore.It is an absolute waste of time trying to re-bore, such a proceedure cuts the tops off the waves, the liners are then even thinner at the point where they are not contacting the bore. the result is a massive circle and the next traffic jam or higher speed run will start the whole problem off again.

From archive chassis card details it does not appear the R-R started to fit full length liners into reconditioned 4.25 / 4.5 engines until circa 1957, even though 4.9 engines had full liners many years before.Of interest is that the original full length liner drawings called for the block bores to be ground and not bored.Production liners were also bored 0.015 before final fitting/ boring and honing to avoid distortion of the bores. This distortion or collapse is caused by the inward pressure aggrevated by boring out. It is very sound practice to leave these blocks at least a week after pressing in the liners before boring and another week before final honing.This gives the liners time to creap / move into their final positions between the operations.
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Norman Geeson (
Posted on Wednesday, 03 July, 2002 - 07:12:   Edit PostDelete PostView Post/Check IP


Forgot one point, the reason that hard liners are a problem is that they have very little or no wetting characterisc, in other words they do not retain oil on their surface structure easily. R-R tried full length hard liners experimentally before the experimental department moved to Crewe. They were a disaster and resulted in almost immediate piston scuffing. Later on at Crewe about five sets of pistons were fitted to one engine, only to find they all scuffed / seized on road test, then it was found out that the engine had been fitted with hard liners originally (experimentally) and run in very very carefully.The only engines fitted with hard full liners were a few fire engines that did very little milages on cold engines, these had special clearances and were run in extremely carefully.The milages covered were somewhere in the region of 3000 miles in about 5 years, no good for a car.
Yet another reason why the hard top cuff type liners were also a disaster, any three quarter liner fitted to the bottom of the bores by R-R was made from a different material.Pistons and rings do not like hard liners, they do like some oil! Incidently it is imperative to allow larger piston clearances than originally specified to achieve good piston / ring wear.
Very good pistons seem to be produced in Australia by J.P pistons and these have larger clearances, except they dont seem to be able to gap their rings even roughly, including the oil ring rails, so beware check the gaps
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Bill Coburn (
Posted on Wednesday, 03 July, 2002 - 09:07:   Edit PostDelete PostView Post/Check IP

Can I compliment the correspondents for their exchanges which have made fascinating reading And I thought I was being very careful and thorough when I rebuilt the engine of SDB94 a
4 1/4L block. Under the tuteledge of Bert Ward and Don Appleby I, as an absolute amateur stripped the motor and cleaned the water passages meticulously with scraping and acid until they were undoubtedly cleaner than new. Full length liners were fitted with standard pistons and the latter were lapped in with Brasso and oil after having their gudgeon bosses smacked judiciously. The gudgeon pin bushes were also fitted with great care as they tend to knock at a relatively low mileage. The honing I remember was done with the studs in place but not with the water pump adapter fitted. Curses!! I was so proud of that engine which ran and I am told still runs like a clock after 35 years and three more owners.

Now that the whole Factory practice and ethos have been exposed it is fascinating to read the spin their very capable PR people put on at the time to protect their reputation while all the above drama was being played out.
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Richard Treacy (
Posted on Wednesday, 03 July, 2002 - 19:56:   Edit PostDelete PostView Post/Check IP

Perhaps this is boring 70s stuff, but I would like to comment on Bill's work on SDB94. Bill, it was not 35 years ago, but less than 30 years ago (ca 1972) that you restored SDB94. For those that don't know, Bill acquired this car from a well known Canberra doctor (name remembered but not quoted !) in about 1971 upon Bill's return from the USA. The doctor was a Mercedes fanatic and rubbished this poor car regularly, especially for its rust, at our club meetings before quitting. Compare a 1970 Mercedes to a Silver Dawn today and see what shines !! I was 15 at the time and already an RROC (A) member as my father owned an R-Type, B174UM, which I pinched from him in 1976 and still own.

Before restoration, Bill drove this then black Silver Dawn to my father's home once around 1971 sans front wings. The police stopped him along the two kilometer drive, and were amazed that he had a permit to drive it in that state for the weekend. At the time, the motor was very quiet except for a loud tick once per revolution: was that a small end Bill ? I forget.

Bill's newly acquired Silver Dawn SDB94 was then in dodgy condition, with quite a lot of rust. Bill did an amazing last-nut-and-bolt restoration within one year. At the time I could not understand why even the good bits needed to be rebuilt. Finished superbly in Midnight Blue by Bill himself, it was absolutely the envy of the city if not the country, and in unbelievably pristine condition after all Bill's work. Afterwards, the car was as shiny underneath as outside. With the body off, all rust removed, and everything dismantled, Bill straightened the bent chassis on a special rig at the local panelbeaters, removed the original chassis rivets and welded it to R-Type specification as designed by Bert Ward of York Motors fame around 1950. Incidentally, Bert's welding design was adopted for series production unaltered by R-R for the R-Types/E Series Silver Dawn without acknowledgement. The welding included several fillets attached behind the front suspension. Welded chassis were needed in Australia especially in the 1950s wool boom for lumbering down farm roads with the sheep in the back. Cracks and loose rivets were the norm with standard Mk VI/SD chassis. Hence, in despair Bert Ward devised the modification and implemented it on many Mk VIs especially, long before the factory admitted there was a fundamental problem. Bill converted the motor to a full flow filter setup the same as on the 4 1/2 motors, again to factory specifications, and fitted the mandatory full length cylinder liners. Among many other R-R prescribed improvements Bill accomplised was the third motion shaft gearbox modification and installed the heavier clutch.

SDB94 was the quietest Silver Dawn I have ever heard. It put my tappety R-Type to shame. I too put full length liners in my R-Type, which to this day has Australian REPCO pistons and Jaguar 3 5/8 piston rings. Oil consumption is zero. I chose REPCO pistons and rings (injection die cast and tin plated) over JP pistons (sand cast) after previously suffering two sets of Rolls-Royce pistons and their shoddy rings (a gallon of oil per 1000 miles was the norm for these cars, and with the short Brichrome inserts the rings lasted a few thousand miles only). Again, my reboring was done without the water pump studs torqued: I only learned this need recently from Norman. Incidentally, early 4 1/4 motors had flash chromed upper bores. In fact, these were even worse than those with 1/4 length short liners. Motors failed catastrophically when the chrome lifted. Surely, the short liners were purely an emergency fix for a fundamental flaw. My car was delivered new with three 3/4 length liners as well as the 1/4 Brichromes. Maybe the casting was defective or maybe it failed on test.

Just after restoration, the stunning beauty SDB94 was proudly displayed in the middle of the leading department store, David Jones, in Civic, Canberra's modest city centre, perched on four Wedgewood cups, a contemporary Wedgewood advertisement. I remember seeing Margaret Whitlam staring at it in awe (she was a regular DJ's patron, and very visible being so tall). There were at least half a dozen Mk VI-R-types and two Silver Dawns in Canberra at the time. The other Silver Dawn was a rare H-Series Hooper Empress 1954 car brought from the UK in 1970 by a still-RROC (A) member and "Colonialised" - cooling system overhaul (it boiled on its maiden trip to Canberra - I remeber seeing it boiling at Lake George before we knew the owners) and new suspension springs. That car ended up in France when it was sold in favour of a pre-war Rolls-Royce.

Norman's relevations are startling. Only those who have persevered with these gems could digest the facts without a heart attack. Bill, after all the factory prescribed mods you carried out on SDB94, you must be one of those.
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Bill Coburn (
Posted on Wednesday, 03 July, 2002 - 23:09:   Edit PostDelete PostView Post/Check IP

Richard I blush to the roots of my white hair (I am now 65 and still think of Richard as a 15 year old boy). Seems I am not growing old gracefully. Before my critics leap to trivia, I realise there are a few minor embellishments above but given the current pasting I get from my local fellow Club members, Richard's sentiments are balm to my wounds. Thankyou.
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RTreacy (
Posted on Wednesday, 03 July, 2002 - 23:23:   Edit PostDelete PostView Post/Check IP

Correction: the Hooper Silver Dawn is an R series 1954 model.
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Jim Bettison (
Posted on Friday, 05 July, 2002 - 11:10:   Edit PostDelete PostView Post/Check IP

Your article (and illustrations) travelled well. So far we have been through it twice, appreciating the points you have made. The work you have obviously put into it is truly magnificent and will help us enormously in our task.
We have two cars which need work; one of them, a friends Dawn, has been started. The other is my MkVI, about which there has been some past dialogue at this site. The MkVI suffered my inattention while in extended storage (didn't keep it turned over regularly and oiled in the cylinders) or so I thought. Now I suspect that out problem might have emerged anyway. Particularly, there are substantial discontinuities at the junction of the top liner with the lower bore, visible with a borescope - and producing audible noise, we think. (The noise has to be audible or we wouldn't know it existed!) We had already decided on a rebore/resleeve, and your article will help enormously.
I may write a small account of our dealings with this car, when finished - if that happy state ever arrives ... to cover things like "wrong" carburettors, the effects of modern so-called fuels and their volatility, the function of Oil Bath Air Cleaners in assuring that inlet air comes from the hottest part of the engine compartment, the ways of getting sludge out of an engine block (ever tried a length of speedo cable in a variable speed hand drill?), the changes of operation as between various spark plug makes, etc., etc. And all of this with a population of less than five cars.
In the meantime, thanks again for en excellent article.
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Norman Geeson (
Posted on Monday, 08 July, 2002 - 06:20:   Edit PostDelete PostView Post/Check IP

Well Guys this must be a case of International support, Australians, Americans and the English, we could start the third world war at this rate!

To Bill Coburn
I doubt you did much wrong with your Dawn or it would not have lasted long. Glad you enjoyed the list exchange on the topic, bet Bill Vatter did not know his question would entail the worst brains from three Continents! Another small point, the archives do mention the small end bush problem in discussions with the R-R suppliers. R-R found that the imbossing of the star shaped detent in the bush caused slight distortion AFTER the bushes were reamed, from memory the best they came up with was to ream accurately and complete the reaming in a bath of oil.
By the way, Richard must still be 15 years old, who else would actually pinch an R type!

The conclusion about the liners tilting as the piston goes over TDC and the wave wear problems are my own conclusions after bringing together a few years of experience and reading between the lines on some of the archive material.

You should see the archive material on the crankshafts and dampers that makes the hair really curl.The subject of my next article I hope.

To Richard Treacy,
I still see you are out there, keeping an eye on the latest. Didn't know that you went in for pinching R types. Now I know how you enjoyed R-R engineering whilst saving up for that Turbo R!

To Jim Bettison,
Glad the article and enclosures came over clear and that you seem to have enjoyed your mammoth read.Yes, I am afraid the air intake temperature is not good with the normal air cleaner let alone the oil bath mounted over the exhaust. I have often thought the engines would benefit greatly from a source of fresh air, possibly from an under wing air cleaner intake or a tapping to the right hand front "horn grille" area.

The block are indeed difficult and hard work to clean especially under the deck area, flexible drives can indeed help.

As you have gathered by now from the article, this excess heat was the reason that R-R fitted exhaust valve seat inserts in the 4.9 Ltr engine and their engineers were recommending fitting exhaust seats to all 4.5 engines and would have liked to have done so with the 4.25ltr.This was to break the heat transfer path between the valve and the block and prevent cylinder blocks cracking from the valve seat towards the liner.You would be wise to consider fitting exhaust valve seats in your hot climate.

To Bill Vatter
Well you started something didn't you?
Next time I am in the archive I will look to see if Silver Wraith WFC10 ever had a reconditioned Crewe engine and if so which car the engine came out of originally.
The archive files on liners do not particularly mention the coeffients in respect of heat flow to the block. R-R did however run pistons directly in alloy blocks and considered screwed liners at one stage, the latter quickly dispelled because of the lack of material in the deck area.The same reason, also stopped eventually, a top flanged liner, the latter fell by the wayside during tests to "Dieselise" the engine.Whatever the coeffients, both top cuff liners and full liners moved away from the parent bore adjacent to the top deck. Although it should be said that this movement was only after some hours of test bed running, at full throttle, at about 3500 rpm. When one considers the engine design, the exhaust valve and port being in the top deck on one side of the liner, it can clearly be seen that the top of the liner is subject to tremendous heat and temperature differentials.
Personally I am a big believer in taking the baffles out of the rear silencer resonator box to reduce the exhaust back pressure, it really does relieve some of the excess heat in the valve area. R-R actually produced one R type in the TO/TN series with a straight exhaust at the rear, that is they fitted pipes in place of the boxes, at the customers request. My own R type has no baffles in the rear boxes. The only time it can be heard anything like intrusively is when the engine is running on the choke. The rest of the time the exhaust noise is rather like that emitted by a R type Continential.
I hope you have received your article copy by now and some of the subjects we have discussed are much clearer.

Best Regards to you all.
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Bill Vatter (
Posted on Monday, 08 July, 2002 - 12:44:   Edit PostDelete PostView Post/Check IP


Thanks for sharing your experience and knowledge. I have read through your article and I'm fascinated. Exceptionally thorough, and more than can be absorbed in one reading. It is more like a reference to be studied before a complete understanding of the issues are fully understood. My only negative comment is that you point out so many of the difficult aspects of the engine, one might think the engine is not very good compared with others of the period. Contrary to that I think these engines are actually very reliable and can provide very long service between overhauls, in spite of the cuff liner, if the engine is not abused. My own car, WGC66 with the early block and cuff liners (original engine), has clocked 130,000 miles without overhaul, and it is running very well. That is a pretty long life for any engine of that time. Perhaps there are some broken rings, but the compression is still very even at about 115 psi. That's higher than theoretical, but perhaps there is some hard carbon in the combustion chambers.

Regarding caring for the engine, I started another thread regarding coolant, which I would like to hear opinions from everyone.
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Bill Coburn (
Posted on Monday, 08 July, 2002 - 14:26:   Edit PostDelete PostView Post/Check IP


And a thanks from me also. The thirty odd years I have associated with Rolls-Royce and their products I have been beset with owners and enthusiasts who regard the whole milieu as one verging on the sacred. It took me some years to realise that this was not the case, that the whole exercise was fundamentally a commercial exercise, that people who designed these products were not divine and as the Works Superintendent said to me at the factory many years ago 'They are only a car you know'. But we love them, put up with their foibles and now with the insight and professional assessment of independent enthusiasts such as yourself we can enjoy them even further. And thank God you are around since I together with a small band of enthusiasts have been associated with a group of owners who regard technical discussion of faults with their cars as akin to a detailed analysis of the photographic record of one's last colonoscopy! May you live long and contribute abundantly!
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Jim Bettison (
Posted on Tuesday, 09 July, 2002 - 11:56:   Edit PostDelete PostView Post/Check IP

Continuing thanks all round, and a few comments. Bill Vatter, my first response to your concern about your engine's inner cleanliness is "If it ain't broke, don't fix it" - which is really a response more applicable to your other thread, where I will also appear! A comment about heating (or overheating) follows, particularly sparked by Norman's response. It's in the context that 30degC is usually just a slightly warm spring day; our cars often have to contend with ambients of 35degC or more. We have measured temperatures of 55degC under the bonnet of our MkVI when travelling on a 25degC day, and a couple of things we have done have helped ameliorate the problems exacerbated by these temperatures. First, we removed the oil bath cleaner and associated "boom box" silencer and fitted a dry air cleaner/filter direct to the air intake plenum supplying the carbs. It has done nothing useful for the induction noise - but more of that later. Then we fitted a piece of stiff insulating board about 6" x 4", held in place by two cable ties around the front carb fuel chamber, so as to screen the front carb from the fan-generated air stream. Previously, the front carb body and fuel chamber was at least 5degC hotter than the back one, when measured with our little Taiwanese digital thermometer; now the two carbs are virtually identical. At this stage I should mention that we are convinced that, in the Oz market, the present-day fuels, in addition to their other characteristics, have a lower boiling point - hence the need to keep things cool.
Spark plugs have helped - we now use NGK one step hotter than the old Champions, and with a longer reach. This has resulted in a cleaner plug, and some reduction in operating temperature, we feel.
The largest step is one that would doom us forever in the circle of some of Bill Coburn's friends. The exhaust manifolds, always fragile since I have had the car, were near end of life. So we have replaced them with a pair of 3-branch headers and branches that double into the existing exhaust system, now modified, at about the bell housing. All are lagged. We have put an alloy shield/deflector above the system, and have left off the undershield. Result is about 8degC to 10degC temperature reduction, some of which benefits the starter motor and some for the passenger's feet.
We are seriously contemplating a shroud for the fan. Norman, I haven't checked which fan/pullet combination we have. Your exposition on that will be helpful.
Also, we have been looking for a way to get cooler intake air to the carbs. We think there might be a way between the radiator shell and the radiator core - more on that later. A solution would also quieten the induction noise.
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Bill vatter (
Posted on Tuesday, 09 July, 2002 - 13:46:   Edit PostDelete PostView Post/Check IP


Regarding carb air, I have seen a car with an induction pipe that took air from the space between the radiator and the grille shell above the mounting bracket on the radiator. This was hand fabricated from thin aluminum sheet made into a rectangle that fit the opening alongside the radiator transitioning into a 3 inch diameter pipe that fed to an air filter housing that came from a junk yard. The connection between the hand formed air scoop and the filter was flex hose.

The air filter was about 12 inches in diameter and mounted directly to the single down draft stromberg carburettor. (this was a left-drive car) This filter housing was from some junk car and it took a round paper element about 10 inches in diameter.

I frankly thought it was not very good looking and certainly would have been points off in judging, but it did appear to be effective.

Cool air is more dense than warm air, so more will get in on a full throttle intake stroke, and more power will therefore be developed. However, I don't see how this can lower operating temperature in a significant way.

On another point, lagging the manifolds could help under bonnet temperatures. Do you know anyone who has lagged the stock manifolds? I would be concerned that the expansion associated with higher temperature cast iron manifold could cause it to break. What material should be used for lagging?
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Jim Bettison (
Posted on Tuesday, 09 July, 2002 - 22:45:   Edit PostDelete PostView Post/Check IP

You and I are both talking about finding cool air through the same space. We are looking at using the silencer normally mounted over the rocker cover in the same (existing) position and mounting inside it a dry filter element(or two)plus necessary dividing walls, etc. The exit would be, as now, to the plenum ahead of the carbs. The main difference would be the duct(s) from the intake space above to the silencer. We have thought of moulding it from the thermoplastic used in modern cars to form ducts, shields, etc (name escapes me - will come back with it when I remember; age again ...) - which has the ability to be made to look neat.
The main reason to get cool air is to promote more even running with the volatile c*t p*ss that's now sold here as petrol, by ensuring that it doesn't boil in the carbs.
We didn't lag the manifolds because they needed to come off for welding anyway. (By the way, all the things we are doing to the car are completely reversible - no excess metal is cut and none discarded. We could restore to original build in a couple of days, if wanted ... but why?) One other reason to make up branches and headers was to help overcome the power loss with the factory manifolds. I understand that the 4 1/4 litre MkVI engine lost around 43 BHP when the manifolds were connected vs. the "open" exhaust power. The manifolds used on the 4 1/2 litre car lost much less - I think around 25 BHP (will check these figures and advise). One regret we have is that our friendly local dynamometer facility went u/s just when we wanted to do the "before" run. The "after" run might happen any time from now. The advantages we got were two: cooler engine compartment and better running. The branches are formed from 1.75" dia mild steel tube, and fabricated from standard bends.
I'll get the name of the lagging we used and hope that it's also in USA.
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Jim Bettison (
Posted on Thursday, 11 July, 2002 - 10:56:   Edit PostDelete PostView Post/Check IP

To correct and add to my last posting: The material that we are looking at for making up a duct directing cool air to the carbs is ABS plastic, drape moulded. (Advancing age - couldn't remember ABS!!)
Engine performance: Ken Lea wrote that the MkVI exhaust caused a reduction of 28 BHP as compared with an open exhaust. The exhaust manifolds fitted to the later (big bore/small boot) MkVI and R-type (M- through P-series) caused a 9 BHP loss. What we have done has, I hope, shifted the loss of B20JO towards the lower end of the loss spectrum ...
Bill; about lagging. We used an Oz product probably not available in USA that goes by name of "HIGH ENERGY KOOLTUBE - HEADER WRAP". But I do know of an US product that you should be able to get at your friendly local speed shop; it goes by the name of "COOLTEK". They also offer fixing clamps and protective paint for the wrap.
And I got the diameter of the steel tube used for branches wrong; it's 1 7/8", which reforms nicely to mate very well with the head ports.
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Martin Cutler (
Posted on Friday, 12 July, 2002 - 09:54:   Edit PostDelete PostView Post/Check IP

Hi Jim,

Interesting reading. What specific model of NGK plug are you using? I use BP6ES, (extended point), in the 4.5 litre Mk VI. As my car was a cooach built model, it has no oil bath filter, just a dust filter on the end of the "barrel". I noticed a great improvement in power with the fitting of a new exhaust system but retaining the existing manifolds. I agree with you, under bonnet temperatures on this car are very high. Does taking the oil/splash pans off from the sides of the engine bay help? I thought this may help concentrate the air going through the radiator through the entire compartment, rather than dissapating to the road. I wonder, do you think you could fit the lagging tape to the existing headers?

I haven't had a hot day yet with the newly fitted thermo fan, but will keep you posted.
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Jim Bettison (
Posted on Friday, 12 July, 2002 - 11:35:   Edit PostDelete PostView Post/Check IP

Yes, we do use BP6ES plugs, with the extended point. However, see later - we may change again. The BP6ES responds well to an optimised fuel/air; we have an analyser, and check the performance and mixtures on the road. At present we have about 14.5 on cruising, both level and uphill, dropping to about 11 on acceleration. However, the exhaust is still black, and the plugs tend to look more sooty than we like. We are about to fit a "Fuelstar" unit - one of the tin-based slow-release catalytic additive systems - and experience of others has been that it improves power and fuel consumption. At the same time, the catalyst assists in more effective combustion, and the consequent lesser quantity of free carbon induces a tailpipe colour that we are more used to, and plugs also become "hotter". Whether this will warrant a plug type change is yet to be discovered. The tin also assists in valve seat preservation. Will keep the Forum advised.
Yes, I believe that removing the nearside undershields does help. We have placed a large new shield at about the level of the head/block junction, to encourage air to exit downwards.
I don't have experience of what I'll call the "R-Type" manifolds. But it should be possible to insinuate "Kooltube" or equivalent through the gap against the block. I would lag from as close as possible to the manifold flanges at the head to about 12" - 18" from the forward silencer.
The measures I've described have, we think, achieved the heat reduction I mentioned earlier. Good luck.
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RHTreacy (
Posted on Friday, 12 July, 2002 - 19:41:   Edit PostDelete PostView Post/Check IP

Hi there,

If you want it, e-mail me for an Excel sheet cross referencing most spark plugs ever produced by brand and by type, eg BP6ES = Champion N9YC to N11YC etc. The list includes indicative prices in USD.

I must say I have never had any problems with the Champion N8 plugs in hundreds of thousands of km on my 4.5 R-Type. Platinum plugs, like on RR/B sice 1986, last extremely long and are much lest soot resistant, but if it goes 100% on N8s, why change ?

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RHTreacy (
Posted on Friday, 12 July, 2002 - 20:20:   Edit PostDelete PostView Post/Check IP

I can also e-mail a PDF file of a table explaining the meaning of the NGK part numbers.

For example, a 1987 Turbo R uses type BPR4EVX, a B=14MM thread, P=protected insulator, R=resistor, 4=highish heat rating, E=19mm reach, VX=high performance platinum plug. Expensive.
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Jim Bettison (
Posted on Friday, 12 July, 2002 - 22:46:   Edit PostDelete PostView Post/Check IP

Your offer to provide the info on spark plugs is gratefully accepted. Can you provide the Excel s-sheet as an attached document? and the PDF document also?
My e-mail is
My inclination is to never refuse technical info ... the problem is filing/cataloguing it.
Why change from Champion N8? Because they seemed not to be working as well as they once did, tending to wxhibit a variety of conditions of heating or sooting when removed, and changing from them helped materially to improve the smoothness of running. We will try soon the NGK "V" plugs, and possibly also the Bosch 4-gap offering. The cost of a couple of sets of plugs is rather minute when compared wih what's already been spent ... Your comment about the Pt-point plugs reminded me that the best plugs ever in my '54 TR2 were Lodge Pt-pointed - long gone.
Today I saw a Dawn (1951 engine) that had the head off after about 9 months and a few hundred miles since proper reconditioning. Don't yet know which fuel is being used (the owner is out of the country just now) but we were appalled by the heavy carbon deposits - just like 50 years ago and decokes every 10,000 miles. I am coming to like the modern fuels less and less.
(As a matter of interest, we tried a range of needles, using our portable exhaust gas analyser - see the earlier post to Martin Cutler. We found that SB needles are the most appropriate with the present set-up and fuels - we suspect particularly the latter.)
We are contemplating, just for the experience, taking the car to the local light aerodrome and getting a tankful of 100-octane leaded, plus some good upper-cylinder lubricant, to see if we can recapture what it used to be like ... saner counsel will probably prevail ...
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Jim Bettison (
Posted on Thursday, 18 July, 2002 - 22:44:   Edit PostDelete PostView Post/Check IP

We started this thread with a query by Bill Vatter that Norman Geeson answered, and we've covered a lot of territory since, to the point that I now have a query on a similar line to Bill's original request!
One of our group is doing a lot of work on his Dawn (chassis SFC32, and engine S16C.
On the end of the block, to the rear of cylinder #6 and concealed by the flywheel, cast proud just like Bill's, is H, and about 1" below in the same casting method are the numerals 55, all in about the centre of the casting face.
But it doesn't stop there.
About 1/2" below the top face of the block, punched in, is a single horizontal line H55L (the style as to type afce and letter height is very like the engine number) and mostly about the same size; the L is about 1/16" larger than the first three letter/numerals.
Can anyone tell us what it all means, please?