Stainless steel Valves

[Deleted User]

HI - I am doing a valve job on a 308 and may need new valves. I have used s. s. ex. valves in 2 engs. (a 262 & a 308) in the past with no problems. I have heard a few stories about s. s. ex. valves sticking in the guides lately. Does anyone have any ideas on this? Walt? Thanks Norm

[Deleted User]

Are you using new valve guides?

[Deleted User]

Most that have valve sticking problems are due to the valve guides not properly cleaned after the valve job. Need to spray carb cleaner on pieces of rag and force down guide with a phillips screwdriver. Secondly , when a valve job is compeled, the spring height needs to be checked and the valve spring pressures checked at that height. Add valve spring shims to bring the seat pressure to 75-80 lbs. I realize most do not have a valve spring tester and height guage, so go to your local machine ship and get .065 shims and clean the guides and lube the valve stems when you reassemble.



Randy

Geoff

If you use stainless valves you must give extra clearance in the guides. Most sticking problems with stainless valves are because the valves are too tight in the guides, particularly if you are using bronze liners in the guides, as is common practise these days. You also must set the tappet clearances with the engine thoroughly warmed up to operating temperature. You don't need a wider than normal tappet gap unless you are setting them cold, and it is only guesswork at that as you don't know exactly how much the valve stem will lengthen when expanded under heat. Incidentaly, the valves originally used in the Jet were bi-metal - stainless above the guide. This eliminated any problems in this area, so Hudson engineers were right up there! I don't know if the original valves in the big motors were the same, but replacement valves today seem to be all stainless.

Geoff.

hudsonguy

I know Dale Cooper has bi-metal valves available. I think he has them for all size Hudson engines, if I'm not mistaken.

SuperDave

I have heard of guide clearance problems with Model A Ford engines when using stainless valves. The expansion rate is greater for the stainless alloy. I guess you need to ream the guides a little larger, but how much, is the question. It ain't funny when a valve sticks..but at least it's not an OHV engine where it would be certain disaster! Had it happen on a 358Chevy. When it blew' I found some compression rings lodged in the carburetor butterfly! It was only turning 7200RPM at the time. Ahh the joys of a flat head..Just take the plug out and knock the valve back down. Back to basics.