| Author | Message | ||
     David Lacey Frequent User Username: dlacey Post Number: 52 Registered: 11-2010 |
All, My car SRH4452 runs fine in the Malaysian heat with the temp mostly in the white 'normal' zone of the gauge. I have the mechanical fan plus two electric fans. However in heavy midday traffic the temp will creep up, out of the white but still well 'on scale'...then the car starts to misfire & stall. I tried a richer mixture to no avail, then once i opened a float chamber when it was hot & found the fuel 'boiling'! - i have a video.... In fact, under these conditions, when I switch the ign off there is a boiling & hissing which is fuel coming out of the carb float chamber vents! I see introcar do a thermal isolator for the carbs...has anybody fitted it or have any more comments on it? http://www.introcar.co.uk/new-products-c37550/manifold-to-carburetor-heatsink-kit-aftermarket-product-p270121 | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 806 Registered: 5-2012 |
Hi David I'm guessing you have been running your car quite happily in Malaysia for the past few years and this fault has just appeared. If this is the case, then something has changed. In my view fitting a thermal isolator will just be compensating for the real fault. I had a similar problem which I cured by fitting a new viscous fan coupling. i.e. I got the main fan back up to maximum efficiency. The difference to the old one is quite marked, even though at the time I thought the old fan coupling was quite efficient. If the fan on your car has gradually declined in efficiency the point may have been reached where the under-bonnet temperature is starting to get too high. As a point of interest, are the float chambers on your car fitted with plastic inserts? I have put up a couple of photos of the ones on my SY1 in this thread: http://au.rrforums.net/forum/messages/17001/17673.html?1433093676 According to the service bulletin, Crewe introduced these in response to some reports of fuel vaporisation on S2s' and Clouds'. They obviously continued with the mod when the Shadow was introduced. I think the principle of the plastic inserts is to displace fuel at the bottom of the float chamber so there is a higher proportion of cooler fuel coming down from the top. I removed the ones from my car as the springs supplied in a reconditioning kit were too long. My view was I could always refit them if I started to get fuel vaporisation problems, but this has not occured. So, even though I have removed the Crewe fix, the new coupling has provided enough cooling air to cure the vaporisation problem I had. It is certainly worth checking out this possible cause on your car. I am in Florida - ambient temperatures are 90F during the afternoons here. Geoff. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1460 Registered: 6-2009 |
David, I am not quite certain by what you mean by "out of the white, but still well 'on scale.'" The white band is the range of "within normal limits" for operating temperature on these cars. I can imagine that you might get above the white band before the overheat buzzer sounds (since by every report I've ever seen it sounds far too late - the engine damage is done) but above the white range is running hot. Modern fuels will definitely boil more easily than those used in the past, but this is not the result of the addition of ethanol (which I doubt is being done in Malaysia). Gary Phipps, a member of the RROC-US, has done a lot of original research into fuel boiling, particularly in pre-war cars. I only have one document on that, and it wouldn't be any use in answering your specific question regarding this product. I do know that he's found that a great many of the insulation schemes that have been tried not only frequently don't work, but often make matters worse. It would be interesting to see how this thing is arranged. A well-designed heatsink really can make a significant difference. Brian | ||
| Chris Browne Prolific User Username: chrisb Post Number: 222 Registered: 2-2010 |
Hello David, Geoff and Brian, A friend of mine has a 1974 Shadow 1 and for the past few months, after a long run in summer temperatures in the UK, (so not THAT hot!) it was difficult to restart the engine from hot and it gave all the symptoms of fuel having evaporated from the carbs. We happened to spot the ad for the isolator kit from Introcar and thought we'd give it a try. I had a spare inlet manifold with carbs from a Shadow 2 which was already fitted with the thicker isolator. The original isolator on the Shadow 1 was only paper thick. We lifted the carbs assembly and replaced the isolator with the thicker one and the longer centre bolt. Since that home made modification, the fuel evaporation problem has disappeared entirely and we have been having temperatures in the low 30's in the UK lately. It would seem that the extra thickness of the isolator insulates the carbs from the heat of the engine just enough to stop the evaporation of fuel. I presume that was the reason the thicker isolator was fitted as standard on the Shadow 2's. Kind regards, Chris | ||
| Mark Aldridge Prolific User Username: mark_aldridge Post Number: 226 Registered: 10-2008 |
It is worth checking the air intake cold/hot air flap is working correctly; particularly the vacuum control valve in the air intake housing. Blanking off the hot air supply has cured fuel evaporation problems and rough idle when hot in warm weather on both my Shadow 1, and a friends Shadow 1 which he uses used in the wedding trade. Mark | ||
| David Lacey Frequent User Username: dlacey Post Number: 53 Registered: 11-2010 |
All, Thanks for the ideas.. a little bit more data on the car condition: 50K miles, recent recored radiator, rad cowling fitted off a later car (early cars didnt have any), fan is the metal type without a viscous coupling, so its moving a lot of air. There are two electric fans mounted in front, 'always on'. If i run in 90-95 F conditions with some stop-start driving it stays comfortably in white zone. Stationary for 15 mins still in white...after 30 mins starts to drift above the white zone, never goes off-scale, never boils...get moving & it comes back to white zone quickly. No overheat warning on this '68 car. Geoff quite rightly questions if I'm treating a symptom or the rootcause...answer is I don't know...it's never run well in this heat, I have taken sequential steps to improve cooling and its now much happier (recalibrated distributor was major factor in rough running). The fuel is definately boiling, as said I can see it spitting out of the overflow onto the ground on hot shutdown. Geoff mentions plastic inserts, I must say that I havent dug into the HD8s as they appear functional...no evidence that the car has been altered from original spec. Introcar call it a heatsink, but thats clearly wrong, its a thermal isolator (heat barrier), and Chris's input that this is standard on later cars gives me some confidence. It seems it is a heat soak issue from the block, the carbs keep cool with the air flowing thru them, but get hot to boil the fuel after shutdown. Mark mentions a hot/cold air flap....do I have one? I must go research that... In 10 days time I take the family to Thailand in it...we've done it before...shouldnt be too much midday traffic...but I will encounter crappy fuel in Thailand (http://www.ptgenergy.co.th/product/fuel/EN), this '68 Car prefers 100 Octane...i run it here in Malaysia on 97 (no Ethanol). In previous years its behaved badly when hot, running-on, and pinking and prone to stalling when parking...I'm hoping the improved cooling will partially alleviate these 'bad gas'habits. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 807 Registered: 5-2012 |
Hi David In light of what you have just written, I personally would go the route you originally mentioned and that Chris recommended i.e. fitting a thermal isolator. In fact, I am now thinking of fitting one myself. The first time I removed the carburetor assembly on my car I was surprised to find there was only a thin paper gasket. Seems to me this is a very good upgrade, particularly in view of the fact the SY2s' use the thicker isolator and the results Chris's friend achieved by fitting one. Mark - I have checked the manual and looked at my air intake system and cannot find a hot/cold flap. My car does not have the original air duct that runs from the air filter to the carb intake plenum. Was this hot/cold flap a part of the original duct? I'd be really interested if you could point me in the right direction as ambient high temperatures are an issue to me. Any additional cooling would be very welcome. Geoff | ||
| Robert Noel Reddington Prolific User Username: bob_uk Post Number: 248 Registered: 5-2015 |
The thermal insulator can be made from hardboard. The existing dowels will be too short. | ||
| Bob Reynolds Prolific User Username: bobreynolds Post Number: 280 Registered: 8-2012 |
The hot/cold intake duct was one of the emissions kludges introduced on most UK cars in the early 70s. My 75 Shadow used to have one.  It is underneath the wing, where the air filter is. You will find a diagram of the system on page U70 of the workshop manual 'Temperature-controled Air Intake'. Basically there is a moveable flap underneath the wing, that directs a mixture of cool air and warm air into the air filter, to try and regulate the temperature of the incoming air. The warm air is picked up by the hot air scoop above the exhaust manifold. That's the thing that you have to keep removing to get at the spark plugs! If your car is fited with this scoop, you will see that the hose disappears into the wing. The moveable flap is powered by a vacuum, through a heat sensor on the inlet elbow. The idea was to enable a finer control of the fuel/air ratio by trying to keep the air temperature constant. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 808 Registered: 5-2012 |
Bob Many thanks for the info. You learn something everyday!!! My car has the scoop over the exhaust manifold and the hose does disappear into the wing. I have in the past changed the air filter but never realized there was a hot/cold flap. I'll be checking it out for sure. Thanks again Geoff | ||
| Robert Noel Reddington Prolific User Username: bob_uk Post Number: 252 Registered: 5-2015 |
I have wondered what would happen if the centre bit of the gasket where the long bolt goes through were cut out. So that the carbs cross leak a bit. Maybe this would aid balance at small throttle openings. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 809 Registered: 5-2012 |
On checking my car this evening I find that although my car has a scoop over the exhaust and air duct that enters the front wing, there are no vacuum hoses, as shown in chapter U70. It looks like the air blend valve was added to the SY1 shortly after my 74 SY1 (SRX18501) was born. It does make me wonder whether it would be a good idea to disconnect the air scoop during the hot summer months. I think I'll save that one for such time as needed. Geoff | ||
| Mark Aldridge Prolific User Username: mark_aldridge Post Number: 227 Registered: 10-2008 |
Geoff, the air blend valve is under the front wing on Shadows, and the vacuum pipe runs from under the casting where the trunking attaches to the carbs to the mixer under the car wing. Perhaps this has already been removed ? Blanking the Vacuum pipe to the mixer valve reduced CO by 2 % on my Shadow in hot running conditions. I also blanked off the supply on the Spirit I had and the Mulsanne I now have with similar results. The hot air mix is only necessary in the UK in cold Winter short distance running. Mark | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 810 Registered: 5-2012 |
Hi Mark I have carried out a detailed check on my 74 SY1 (SRX18501) and can see no evidence of the air blend system that is present on yours and Bob Rs' cars. I believe both models are from year 1975, which is why I believe your cars have this enhancement. On my 74 SY1, there is no temperature sensor on the carb plenum, no vacuum hoses and no vacuum tapping on the inlet manifold. The only tapping there is, in the position shown in the manual (U70), is used for a vacuum hose that runs to the speedostat unit. I have not yet checked out the situation under the wing as I have not removed the protective plastic wheel arch shroud. The provision of an air blend valve under the wing by the Crewe engineers is telling me it is not desirable to be piping hot air from above the exhaust manifold in hot conditions. This is borne out by the measurements you have taken on your cars. I'm thinking, as a bare minimum, of removing the short air duct that runs from the scoop over the manifold, whilst running in these summer temperatures. That way the air will be a little cooler, even though it will still be extracted from within the engine compartment. It will be interesting see what I find when I have time to remove the cover under the wing. Geoff | ||
| Mark Aldridge Prolific User Username: mark_aldridge Post Number: 228 Registered: 10-2008 |
Geoff, the vacuum controlled blender appears to be from chassis 17629, therefore if yours is earlier, I would remove and blank off the hot air scoop from above the manifold. Mark | ||
| Bob Reynolds Prolific User Username: bobreynolds Post Number: 281 Registered: 8-2012 |
Geoff's car is 18501, so should have it. In actual fact, I could find no evidence of a vacuum control on mine either! There is no sensor on the air intake, and no tube going through the inner wing. You are supposed to suck and blow down this tube to check that the flap is working. So it's a mystery, unless somebody actually removes the wing liner to expose the innards and discover the secrets. When this modification was added to other cars, a lot of them used a simple flap controlled directly by a bi-metallic spring, which moved the flap over as it got hot. Simple direct control, unlike the over-complicated Crewe solution. I wonder whether Crewe adopted this simpler system. This system is unnecessary and disadvantageous. The engine is far better off running on a cool air intake, giving more oxygen, more power, and more MPG. | ||
| richard george yeaman Grand Master Username: richyrich Post Number: 329 Registered: 4-2012 |
Bob you are right. I had a 760 Turbo Volvo in 1985 it had a 2.3 Litre engine with an Intercooler and it went like a bat out of hell I am sure the cooled air had a lot to do with its performance. Richard | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 812 Registered: 5-2012 |
I've just checked the under wing duct that runs back from the air filter housing. It is clear. I could not see a flap, so my car obviously pre-dates the air blend modification. Here's a photo taken with a camera inside the air filter housing looking down the duct. The red thing at the end is a screwdriver handle I placed inside the aperture that connects to the scoop. I used it to help give context to the photo.  Mark and Bob: I appreciate the info you have given. I have removed the exhaust manifold scoop and flexible air duct. Like David's car, mine runs ok on tickover but it is not perfectly smooth in the hot weather. It will be interesting to see if this "mod" makes a difference. Geoff | ||
| Robert Noel Reddington Prolific User Username: bob_uk Post Number: 257 Registered: 5-2015 |
Car 17768 reporting in. No warm up flap fitted to air cleaner | ||
| richard george yeaman Grand Master Username: richyrich Post Number: 330 Registered: 4-2012 |
Car 19529 reporting in. I don't know my car is away having some paint work done but I think my wheel arch covers are sealed. Richard. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 815 Registered: 5-2012 |
I checked out the price of a thermal isolator kit from Flying Spares. $101 !!!!! Outrageous price for a slither of plastic, a bolt and two dowels I thought. Then I saw Bob_UK's comment: The thermal insulator can be made from hardboard. That's more like it. I read about how wood could be used as a thermal insulator. It turns out wood is an excellent insulator, cheap and easy to shape. However, it soaks up oil and gasoline very easily, causing the spacer to become warped and porous. The author of the article I read recommended replacing it every year to prevent vacuum loss from warping of the spacer. This obviously means making a new one and removing the carb assembly - every year. Not so good, but I still get to save 100 bucks. Further reading showed the best material to use is phenolic resin sheet, which is much more resistant to gasoline but not quite as good an insulator as wood. A foot square of phenolic resin sheet comes in at $25. That's good. I still get to save 75 bucks. Then I read phenolic resin sheet carries a carcinogen warning in California. $10 for two new filters for my respirator, ready for the day's cutting and filing the sheet, to make it the right shape. I still save $65. Of course, a longer bolt and two longer dowels have to be found. I know I'm not going to be able to pick these up at the local hardware store. I guess a local machine shop could make them up for around $40. I still save $25. Actually, thinking about it, $101 for a thermal isolator kit - it's an absolute bargain. Funny how things are not quite as they appear, once you get in to the detail. Geoff | ||
| Randy Roberson Grand Master Username: wascator Post Number: 485 Registered: 5-2009 |
Everything causes cancer in California; their death rate is 100%. I wonder about insulating the exterior of the carb float bowls; anything to reduce the heating effects after shutdown. What about a small fan strategically positioned to take cooler outside air and direct it in this area for ventilation after shutdown, for say 10 minutes? The possibilities are endless... I can't leave it alone. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 817 Registered: 5-2012 |
Hi Randy Lol - I agree. Even household appliance flexes come with their own cancer warnings. I spent a year in California in a small town just outside San Jose. I stayed in a three story apartment block. There were small signs on some of the walls warning that cigarettes may have been smoked in the vicinity of the building and therefore carcinogens may be present. I'm going to fit the FS isolator kit, particularly in view of Chris's friend's good experience with one. Geoff | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1473 Registered: 6-2009 |
For those unfamiliar with Joe Jackson, Cancer, was one of my favorite among his songs. See this YouTube video, which pairs it with what are probably my two other favorites among his oeuvre: Joe Jackson His take on overcaution in that song could be considered humorous protest against California's rampant carcinogen warnings. Brian | ||
| Robert Noel Reddington Prolific User Username: bob_uk Post Number: 264 Registered: 5-2015 |
Phenolic resin is used to make hard board. The long bolt could be a piece of studding 5/16 UNF I believe. The dowels are just plain mild steel ones. I can't see that oil and damp would be a problem. The clamping force of the bolt will stop the hard board from going flakey. In the UK 100% of people die. The way the press go on about drinking coffee, eating food, etc I would think that nobody would actually die if they followed the lastest guide lines. | ||
| David Gore Moderator Username: david_gore Post Number: 1680 Registered: 4-2003 |
My philosophy; why punish yourself by depriving yourself of life's pleasures just to add 5 to 10 years of eating mush in an aged care centre to your life??? Live life to the fullest whilst you can, you will not get the opportunity again. A Shadow/Corniche is a great way to do this from my experience. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 818 Registered: 5-2012 |
“Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming "Wow! What a Ride!” - Hunter S Thompson. | ||
| Chris Browne Prolific User Username: chrisb Post Number: 223 Registered: 2-2010 |
Hello Everyone, I have trawled through my photographs of obscure bits of Shadows accumulated over the years and came across the photos attached. They show the air blend assembly on the air filter housing under the right hand front wing on a cutaway Shadow 2 owned by the RREC and used for teaching purposes. The first one is from the front, the second from the rear. I'm not sure whether the pictures are a help or a hindrance as they don't show the mechanism particularly clearly but at least you can see the layout.   Kind regards, Chris | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 819 Registered: 5-2012 |
Hi Chris Thanks for putting up the photos. The mechanism is clear, with the cold air input at the bottom of the vertical channel that leads to the air filter housing and the hot air piped in from the side. This is totally different to my 74 SY1 and was obviously a major re-design. On my car the channel runs horizontal, parallel to the ground, back from the filter housing and emerges into the engine compartment, about a foot rearward, where the flexible hose is connected. There is no blend valve. The fact Crewe engineers made such a major upgrade is telling me they were not satisfied with the previous, hot air only version. Geoff | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 820 Registered: 5-2012 |
My car now has the manual version - remove the flexible hose in summer, put it back on in winter. Thanks again for the pics Chris. I was intending to take a closer look at mine by removing the wing protector. No need to do so now. Geoff | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1478 Registered: 6-2009 |
Chris, Definite thanks for those photos. I'd looked the thing up and while the drawings are useful there's nothing like a photograph. The only thing I have to say, channeling the purist perfectionists: There is a *rusty* Jubilee clamp and mounting bracket!! The marque is defiled!! Brian, who hopes that emoticons are not necessary for the immediately preceding paragraph | ||
| Robert Noel Reddington Prolific User Username: bob_uk Post Number: 270 Registered: 5-2015 |
The Victorians after Albert croaked. Went into mourning. The new middle class promoted mourning. Where any thing that gives pleasure is bad. The Victorians exported this attitude to the Empire. I think having fun and being contented is the goal in life. Some can't but help themselves at being unhappy. I have a neighbour who blows steam out of his ears just because the bin men broke his wheely bin. They broke mine and gave me a new one. Why kick off. There's quite a lot thought gone into the design of the air filter. The main reason for the warm air flap is carb icing | ||
| David Lacey Frequent User Username: dlacey Post Number: 55 Registered: 11-2010 |
Geoff, You were right in your second post in the thread: "I'm guessing you have been running your car quite happily in Malaysia for the past few years and this fault has just appeared. If this is the case, then something has changed. In my view fitting a thermal isolator will just be compensating for the real fault. " I found my ignition condensor faulty when hot...the misfire was caused by that. The fuel IS boiling due to heatsoak with the engine stopped, but I was wrong to think that was my running problem. The ignition condensor was a quality item from UK, the type flying spares have been hiliting as a solution to other crappy condensors.. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 868 Registered: 5-2012 |
Hi David It just goes to prove that old adage "90% of carburetor faults are electrical" I had a similar problem last April which also turned out to be caused by a faulty condenser. These components are reputed to rarely fail, but two cases in four months shows they are always worth checking out, early in a fault finding procedure. BTW - How did your Thailand trip go. Geoff. | ||
| David Lacey Frequent User Username: dlacey Post Number: 56 Registered: 11-2010 |
Geoff, Thailand went fine...about 1200km at 12 mpg! It dealt fine with the Thai fuel, I carefully chose the best quality 95RON without ethanol. The misfire got worse, always only coming-on once the car was hot...my spares consisted of bulbs, belts, points & condenser and the condenser saved the day. It's the second I have had fail, the first was a 'new'one from FS which they later admitted was poor quality, the one I that failed this time is going back to supplier for failure analysis. I work in Semicon industry, supplying automotive...our customers expect corrective actions and compensation even for 1ppm failure rates...I guess these condensors must fail at the 1/1000 rate these days....capacitors always the weakest part of an electric/electronic system... | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 875 Registered: 5-2012 |
David Thanks for the heads up about the FS condenser. When mine failed I temporarily replaced it with one from a local car parts supplier (Duralast LU506) in order to test the original. Although this substitute part worked perfectly, I have now replaced it with the "genuine" FS condenser. Knowing they had a bad batch means it will be the first part I replace, should the engine start misfiring again. Geoff |
