Wrong valve stem seals???

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MopaR&D

MopaR&D

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Over the weekend I've been swapping intake manifolds on my 318 from an iron 360 4-bbl. one to an Eddy Performer. While I had one of the valve covers off I noticed that one of my exhaust valve stem seals is cracked and loose. I looked at the others and it seems most (if not all) of them are cracked and falling off. This explains why I've had such massive amounts of smoke from oil burnoff but I don't understand how it happened. The heads, springs, retainers, valves, and seals are barely three months old from when I installed them myself. The engine did overheat a bit when I first fired it due to not having the block full of coolant but I can't think of anything else that would cause the seals to crack. Details: Stock 318 short block, reman'd 302 heads+valves, Fel-Pro umbrella exhaust seals (the only ones that broke I'm pretty sure) Comp 901 dampered springs, Lunati retainers, Lunati Voodoo 256/262 cam, stock valvetrain otherwise.
 
Judge Mills said:
My only advise would be to pull the heads and put new seals in...... I'm not much help! :D
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You can do it on the car. Compressed air and spark plug fitting, and a valve spring remove tool.
Maybe they are making the seals in China now. Anything rubber from China seems to fall apart in a few months or less.
 
You'd think Fel Pro would be good?


aren't there two types of seals though? I haven't done this in 8 years, but I thought in the kit there were two types of seals...

still doesn't explain why they are cracked.... maybe they were old and sitting on the shelf exposed to air?
 
That sucker got real hot from break in either due to not enough timing or running real lean.

Use the compressed air or rope method to replace the seals.
 
Where the heads machined for the seals (do the springs have the metal springs on them) or are they just the factory replacement seals? Make sure the seal is the right diameter for the valve stem too. I have seen this mistale happen and the results were as you discribed. You can get different materials for the seals suck as viton, teflon or buna-n rubber. You need to see if the heads are machine prior to ordering the seals and check the valve stem size.
Wayne
 
You must have gotten a bad set of seals. You can replace them with the heads on the block, just need comp air in the cylinder and a special valve spring compresser. Also You can just replace the intake seals, I never install them on the exhaust. You need them on the intake valves only, when the piston is in the downward intake stroke it will pull oil by the valve stem.
 
MD69DartMan said:
Where the heads machined for the seals (do the springs have the metal springs on them) or are they just the factory replacement seals? Make sure the seal is the right diameter for the valve stem too. I have seen this mistale happen and the results were as you discribed. You can get different materials for the seals suck as viton, teflon or buna-n rubber. You need to see if the heads are machine prior to ordering the seals and check the valve stem size.
Wayne
Click to expand...

The springs are single + damper, the ones I pulled off that came with the heads had rotators on the exhaust valves. Otherwise the heads are totally stock (haven't been machined at all as far as I can tell). Did 318's with 302 heads have different-sized valve stems than earlier ones? The seals I got came in a gasket kit for a 1970 318.
 
How much lift does that Voodoo cam have. Could your retainers be pinching the seals between the guide?
 
dgc333 said:
How much lift does that Voodoo cam have. Could your retainers be pinching the seals between the guide?
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Hmm, I was kind of wondering that myself. The cam has .454" lift on the intake and .475" lift on the exhaust, with stock 1.5:1 rockers. Something I did notice when swapping the springs was that the grooves in the exhaust valve stems (for the valve locks) are a bit lower than the ones on the intakes, which made the retainers on the exhaust valves sit a little lower than the ones on the intakes (and thus compressed the exhaust valve springs a little more).
 
If the seals are hard, then overheated'em and they cracked and fell off.

IF they are mostly soft, then you pinched them with the retainer and need to grind down the guides some, like the thickness of the seal for a start.
 
More than likely it's the same seal part number... But I'd order up seals for the 86ish vintage 318 with 302 heads and run them on it. The positive seals are for the intake side, umbrellas for the exh side.
 
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