Head Gasket question (L head)

Little history: My '48 2A had a blown head gasket when I bought it. Nabbed a ROL gasket PN 638540 from 4WD Hardware (it's just the brand they sell). Took over 2 full weeks of soaking to get the head stud nuts off without breaking any of them, but finally got the head off. Pistons are 0.060-over so it's been rebuilt.

Threw the new gasket on (modern type w/ no sealant required) and torqued it down to spec. Fire it up and the valves are hitting the head. Apparently they milled the head when they rebuilt the engine. D'oh.

I browsed on line and go the following PNs for L-head head gaskets:
Peter DeBella: PN WO-A-8558
Northstar Willys: PN 638540 (one I've got that doesn't work)
PN 638540F (Fel Pro)
Krage: PN 63840 (same as Northstar's & 4WD Hardware)
Crown: PN J0638540 (most likely the same as above)

So finally, my question is does anybody know which of these (PN WO-A-8558 or PN 638540F) is the thicker type that requires sealant as opposed to the modern type like I've got now? I'd like to avoid buying both head gaskets to find which one is OEM-type. Tried searching on G503 and elsewhere but this doesn't seem to come up much.

 

Yeah, valves are adjusted correctly.

Another note: engine ran smoothly and quietly with old, blown gasket. It would just overheat quickly and the oil had water in it. The only difference between then and now is the newer head gasket, which obviously has a thinner compressed thickness than the old gasket.

It sounds like the valves are kissing the head pretty good so it's nothing I want to just run as is. Sounds like a thousand tiny ball peen hammers whacking away at an anvil. As a last resort I'll pull the head and relieve it with a carbide bit for valve clearance, but I'd rather just find a head gasket like the one that was on there. (and no - I couldn't find any numbers on the old gasket)

 

Nope - just a different type. Trust me, I looked. The old gasket wasn't but a few hundred thou. thicker than the old one, but the compressed thicknesses seem to be pretty different. If I had to guess I'd say the old one is around 0.040-0.050 while the newer one is probably in the 0.015-0.020 ballpark. Not a lot but enough.

I'll give it till Tues to see if somebody knows what's up. Then I'll just yank the head and relieve it rather than stack 2 gaskets.

 

I may be wrong but it sounds to me like you probrobly have a cracked block or cylender wall. I dont think oil runs through the head. And with it boored 60 over thats a possibility. As for the head hitting id try a different head or maby stack gaskets

 

x2....and why it blew....
.....upon futhur reading maybe not...

 

water does run through the head.

 

Can you call a parts supplier and have them mic the gaskets for you?
Call Turner's sometimes they have old stock on the shelf and might have an old style gasket for you. Heck they had a NOS air cleaner for my 304 in the CJ6.

Have tried the 2a page?

 

Someone must have taken about an 1/8" off that head to get the valves to hit. The motor should have had about 1/8" clearance to start with plus the gasket thickness.

 

I just checked the mccord gaskets I,ve got they are about 80 thousent,s Part # 6086 they are for sale.Mite be a little thicker.

 

I would say somone has shaved the head in the past to get more horse power out of it.R)If you take the head off check the valves to be sure that they are seated,if they arn't and they were adjusted,could be the problem.

 

Just a quick update. Pulled the head this morning for an inspection.

Valves aren't the culprit. The pistons are hitting the steel crush portion of the head gasket. Apparently the gaskets are only for standard bore. They actually came just to the edges of the bores when I first put them on (did think to check) but when the head was torqued down the steel crushed and overlapped the 0.060-over bore enough for the piston to contact.

Looks like I'll try Peter Debella's and give that NOS gasket a whirl. At least I don't need to go yanking the L-head. That's good news.

 

you might have a F-Head gasket on there as the bolt pattern is the same I think .I have two rather thick L-Head gaskets Mccord #6086 if your interested.