|Posted on Wednesday, 02 May, 2001 - 15:05: |
Contemplating helping a mate replace the felt seals on the head of his R Type. Any thoughts or advice on any tricks? Is it a fairly straight forward operation?
|Posted on Wednesday, 02 May, 2001 - 18:27: |
Junk the felt. I had neoprene valve seals fitted instead. They are of the same stem diameter as a Valiant, and a good motor engineer can easily machine the inlet valve guides in-situ to accept the neoprene seals. It does wonders for the oil consumption. I also had bronze inserts fitted into the cast steel guides to improve valve and guide life. All this was done in Revesby, Sydney, but off hand I cannot remember the name of the outfit.
|Posted on Wednesday, 02 May, 2001 - 18:29: |
Junk the felt. I had neoprene valve seals fitted on 1954 R-Type B174UM instead. They are of the same stem diameter as a Valiant, and a good motor engineer can easily machine the inlet valve guides in-situ to accept the neoprene seals. It does wonders for the oil consumption. I also had bronze inserts fitted into the cast steel guides to improve valve and guide life. All this was done in Revesby, Sydney, but off hand I cannot remember the name of the outfit.
|Posted on Thursday, 03 May, 2001 - 11:55: |
Oil Consumption is the issue for my mate. My MK VI seems OK in this area, but his R Type is using oil. Sounds like a good conversion.
Which model Valiant, slant 6?
|Posted on Friday, 04 May, 2001 - 21:12: |
I think it is the 265 Hemi, but any good head shop will know what I mean. The bronze guide inserts are especially good, and the guide itself will last forever. With the special pistons and modern rings (same as a Holden 186 so dirt cheap and they work much better than the R-R rings, which usually break anyhow !!) the oil consumption package is complete. When my R-Type was new, one gallon per 1,000 miles was OK, and that's what it used. Now it remains on FULL always; never uses a drop of oil. The T-Series uses a quart every 300 miles, and the Turbo R nothing at all. York Motors always said oil consumption was only a psychological problem for the owners, but I suffered this distress.
|Posted on Wednesday, 16 May, 2001 - 06:13: |
The early post-war six valve seals work by the packing chamber being under continual pressure from the valve spring. This occurs from the spring pressing down against the lower spring retainer, which piece also serves as the upper half of the packing chamber. With the packing under continual pressure it seals against the valve stem preventing oil from being drawn into the intake passage which is under vacuum during engine operation.
The valve seals (packing) can be easily changed without removing the cylinder head if you have (1) a hook-like tool that goes into the spark plug hole and holds the valve closed when the spring is removed, and (2) a valve spring compresser that squeezes the spring by grasping it from above (as opposed to the type that has an arm to reach around the cylinder head and press against the closed valve).
Anyone can inexpensively make the hook-shaped tool from readily available materials. It is quite like the tool that was generally provided in the pre-war tool kits, which will work if you have one for the later spark plug size (P-3 Wraith and 25-30 + maybe others, I'm not sure, but not the P-2s). Anyone who wants further guidance on this tool can email me.
The factory seal (packing) that you get from the RR dealer looks like a felt disc but is really a graphite impregnated cotton rope that has been wound and then pressed into a disk shape to fit inside the packing chamber below the lower valve spring retainer.
I replaced the valve seals on my Silver Wraith with teflon valve packing rope available from the local hardware store. This was recommended by a shop owner as being much better than the RR factory seal. I used rope that I recall was about 5/64 inch diameter, and I was able to get about eight inches of the rope in there. You need to wind the rope around the valve stem above the cup shaped packing chamber bottom and then place the lower valve spring retainer over the packing and hammer it down with your plastic hammer to compress the packing. Measure the height of the lower support above the cylinder head surface, should be between 1/32 and 1/16 inch after hammering it down. Less, and the lower spring support will likely bottom out against the cylinder head. When this ocurs the seal stops working because it will no longer be under pressure from the valve spring. More distance and the possibility of binding up the valve spring exists. If the valve spring binds up during operation, it will certainly break, and maybe the valve will be damaged. As a precaution, after replacing valve seals it is a very good idea to slowly turn the engine with the starting handle while noting that none of the springs bind. As each valve opens observe there is some space between the coils when the spring is fully compressed. Approach each fully open valve with caution noting the spring does not bind up.
Results with the teflon packing are excellent. Oil consumption was reduced from about 200 miles/quart to more than 400 miles /quart (which I understand is about as good as it gets with this engine). I also now have very clean burning spark plugs.
Conclusion: Teflon seals are great, and the cost is insignificant, maybe a couple of dollars.
|Posted on Thursday, 17 May, 2001 - 21:11: |
The teflon seals I use are a replaceable push-on type, freely available as an aftermarket generic type at a very moderate cost. They are spring loaded at the top to allow for wear (ie like a normal oil seal), and have a very long life. The graphite-wax felt seals from R-R in my experience are useless after a few thousand kilometers, but the teflon rope sound attractive. However, the advantage of the push-on seals is that they use modern technology and are active seals rather than relying on the valve spring to ooze the seal onto the guide.
|Posted on Thursday, 17 May, 2001 - 22:01: |
B175 1954 R-Type Cylinder Head and Valve Guides.
This may be of interest concerning valve guides, seals and heads. I have three cylinder heads: two high compression and one low compression. Both high compression heads have cracked severly several times due to fuel starvation (solution: insulate the fuel line from the tank to the pumps, especially as it passes over the RH exhaust pipe).
I had one cylinder head completely reconditioned, including welding of several cracks, vacuum impregnation sealing, pressure testing, new valve seats, bronze inlet guide inserts (into the old cast steel guides) dimensioned to fit the valve stems exactly (ball push-through method), newly manufactured bronze spark plug inserts and modern teflon seals. To fit the spark plug inserts I bought a metric thread tap close to the original threads and had the inserts made to the same thread of course. Con's welded up the spark plug holes a little, and I drilled the holes and tapped them myself, then inserted the inserts with a nut and bolt of the same size and thread as a spark plug. The inserts are secured by Locktite.
This was in the early 90s, and was done by Con's Performance Centre, 753 The Horsley Drv Smithfield 2164 phone (02) 9609 6333 or (02) 9609 6148.
They also made new bronze exhaust guides for me to pattern. They made the guides from aluminium bronze and the spark plug inserts from magnesium bronze. The spark plug inserts were also made to pattern except for the thread. Set-up cost is the big cost, so a dozen spare inserts and guides were cheap. The quality of the work was excellent and I can recommend them. They are not cheap, and need pressuring to finish the job vaguely on-time, but I must say that the patience was worth it.
Posted From: 126.96.36.199
|Posted on Friday, 25 April, 2003 - 01:41: |
I just received a set of teflon seals by mail order from the USA, including a do-it-yourself cutting tool. The kit was not at all expensive, and there are enough seals to allow a few botch-ups and then do a second car too.
It is Crane Cams part number 99820-16 and comes complete with instructions.
for details, or visit a retailer, for example:
C & V Performance
34 Odea Avenue
Waterloo NSW 2017
Phone 02 96902000
I am fitting these to a 4 1/2 Silver Dawn as the results on my R-Type were so good.
Posted From: 188.8.131.52
|Posted on Friday, 25 April, 2003 - 02:29: |
By the way, the I bought them on-line from Summit Racing with delivery within one week.
The tool costs US$50
and the guides US$24 for 16 stem seals.
Posted From: 184.108.40.206
|Posted on Friday, 06 June, 2003 - 13:31: |
Dear Richard - I have been following your adventures with stem seals with interest and as this is my next project I was wondering how you were progressing. I have a 1950 MKV1 B11 JN and from my research the oil consumption is not due to worn rings as the car has only travelled 30K but I suspect to the packing around the valve stems. You are in NSW I think - I am in Melbourne so any lessions you have learnt I would greatly appreciate hearing - regards Lex Lynch.
Posted From: 220.127.116.11
|Posted on Sunday, 08 June, 2003 - 00:06: |
Recently repaired a friend's valve seals with teflon rope as described here
On removing the springs, I found a teflon umbrella seal over the top similar to neoprene seal shown in second link listed above, but nothing except a little debris where the factory seal is supposed to be. This car had been sucking in a large amount of oil under the seal cap which completely bypassed the umbrella seal that the previous mechanic apparently thought was adequate. Note: whatever you put over the top of the seal cap, you must also have a good seal in the place where the factory intended to have a seal installed.
After installing the teflon rope seal as shown in the second link, this car's oil consumption declined significantly.
regards, Bill V.