Looking for options for vs seals if needed. Not looking to remove heads ,so no positive seals. Viton umbrella and/or oring. Felpro# ?
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Re: 70 LT1 valve stem seals.
Dennis------
Stock-type "o-ring" seals of VITON material (these are not actually o-rings because they have a square rather than round cross section) used in conjunction with stock-type shields will work fine as long as the guides and valve stems are not worn.
There are also positive type seals which can be installed without valve guide machining. I like the ones made by Engine-Tec which incorporate a VITON seal in a metal retainer. These are made for valve guide OD sizes of 0.500", 0.530" and others. These are actually very similar to the valve seals used originally on Gen II (1992-96) small blocks.In Appreciation of John Hinckley -
Re: 70 LT1 valve stem seals.
Thanks Joe. Had a heck of a time sorting through all the choices.
I suspect oil leaking issue. Figure I'll check the easiest thing first. What to check the valve clearances also. If it's the guides, I'll have the heads done in the off season. The compression and leak down checked out ok. Thanks
Saw these from engine tech. Umbrella silicon I believe
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Re: 70 LT1 valve stem seals.
Dennis------
Those might be OK. However, the ones I was referring to have a steel frame with a black Viton seal insert as seen below. As I mentioned, these are very similar to the seals used on Gen II small blocks.
EngineTechvalve seal.jpgIn Appreciation of John HinckleyComment
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Re: 70 LT1 valve stem seals.
Yes. Found that one and this one. Specs are the same. 11/32 and .530 which I assume will fit my 186 head without any mods.
Emailed enginetech to find the differences.
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Re: 70 LT1 valve stem seals.
If oil consumption is suspected through the valve guides, seals are the first choice because they are inexpensive and relatively easy to install, labor-wise. Hope for the best but prepare for the worst. Once the springs are removed wiggle the valve stem with the valve on the seat. You should feel essentially no play. Now drop the valve about a quarter inch off the seat and wiggle... maybe just very slight movement. If a lot the guides are shot, but you can always complete the seal change and see if it helps.
As Joe has stated the OE "O-rings" are not really a round section O-ring, but have a unique square section. The OE seals were nitrile material that eventually harden, crack, and disintegrate due to time at high temperature. Viton has much more temperature tolerance, but I've never found a manufacturer/part number for OE replacement made from Viton rather than nitrile. Most Viton elastomers I've run across are brown, but I'm not sure if that's the natural color or a dye added to ID the material.
I like the idea of a "positive" type seal on the inlet side to minimize oil flow, especially under high vacuum conditions, but I like the idea of just the stem seal on the exhaust side to keep oil from draining down the guide from above and splash from below limited by the steel shield. Exhaust guides need more oil because they run hotter, but there's never any vacuum to pull excess oil down the guide, so "controlled splash" should be okay.
DukeComment
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Re: 70 LT1 valve stem seals.
That's Duke. Your wiggle test has been on the check listComment
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