Valve stem seals with stainless steel valves and silicon bronze valve guides - yes or no?

[EdWills]

The web has a few car forums where owners of cars from small European sports cars to U.S. muscle cars inquire about using valve stem seals with silicon or manganese bronze valve guides.  Some say yes, you should fit them, and others say no with a mix of reputable car mechanics advising either way.  

 

I have a Holbay Ford cylinder head that some describe as Stage II - fitted with larger 1.6" inlet valves, but not so large as to cause possible cracking between the inlet and exhaust valve seats.  The head was new and based on an 1100 c.c. flat cylinder head as there is/was more metal available to grind away for porting (Note: recommendation of David Vizard many, many years ago to use an 1100 uprated flat head on the 1600 c.c. 711M Crossflow which I will be rebuilding).  Holbay fitted harder exhaust seats for unleaded fuel,  stainless steel valves, and silicon bronze valve guides.  Double springs are fitted, but I am thinking of using singles.  Holbay did not fit valve stem seals to the double springs.  I checked with Burton a couple of years ago as I was considering using 'special' stem seals on the valves (with single springs), but Burton did not recommend using stem seals, as they believe that the valve stem and guide would not receive sufficient lubrication.  Some say there is burnt oil smoke on start-up with no seals, and that this goes away quite quickly.  Also mentioned was valve stem seizing if there is insufficient flow of oil due to the seals doing too fine of a job. I have read that tuners installing stainless valves fitted in silicon bronze guides normally specify minimum clearances from new, thereby requiring a good flow of oil.  Has anybody with road or racing experience seen premature wear with stem seals fitted to bronze guides?  I don't want to be trailing smoke and polluting the neighbourhood - even with a car that has no pollution control to speak of - so advice would be much appreciated.  W

Edited Wednesday at 02:10 AM by EdWills

[EdWills]

At the risk of answering my own question, (but to put this post to bed?) I have checked a further couple of books by U.K. Ford Crossflow tuners, and the consensus seems to be that valve stem seals should be placed on the inlet valve at the very least, (to prevent carbon build-up in the head and inlet manifold), but on both valves is preferable.  In my small collection of Ford Crossflow reference books, these stem seals are hardly mentioned, if at all.  With double valve springs fitted, the original Ford factory 'umbrella' stem seals will not fit, but with single springs - which they were designed for - they will work as they were meant to.  David Wallage in his book on tuning the Crossflow noted that some tuners install rubber 'O' rings on the stems for double springs, but he was not fond of this practice, although they will probably work o.k.  I also found the 'Felpro' site and it shows the 2 main types of valve stem seal.  I plan to stick with the Ford 'umbrella' stem seals (unless someone has other ideas), as they will help to limit too much oil going down the guide, but still allow some oil to splash on the stems for necessary lubrication. Cheers, W. 

[IamScotticus]

One question I have is, how do we know the valves get the required amount of splash?  Is oil splash distributed among the valved equally?

I have read the shoulders of bronze valve guides will prevent oil flow to the stem.

If this is true, I would not use seals with valve guides.

One thing I have read is the use of roller rockers will abate valve stem/ guide wear.

Without roller rockers, I would err on the side of allowing more oil to the stems.

Perhaps guides without seals is the best combination?

[EdWills]

Thanks Scott.  It's amazing to find that a number of  car owners have asked this question on the web and there seems to be no conclusive answer.  Even Ai suggests on older (vintage) cars, valve stem seals are not necessary, but it doesn't mention bronze guides.  

 

 

"I took a drive the other day, and parked the car to take a stroll.  Came back to my car and a note on the windshield said "Parking Fine".  It's great when someone congratulates you on your driving abilities".