Head gaskets

[Syleng1]

74’ 318 with .030” over bore.
Felpro 8553PT gaskets.
Machine shop gave me the felpro gasket set when I picked up the block. I started to assemble the long block and saw the fire ring is like 3/16” larger all the way around.
Worth buying proper sized gaskets or no issues and don’t worry? Personally I don not like the bore difference. But I may be over critical of it for no reason.

Syleng1

 

[Plymouth 65]

I've had great results with those gaskets. If you search for a smaller bore size (fire ring) the options are limited. 65

 

[ch1ll]

Yes I'd like an answer to this as well.

 

[ch1ll]

I believe Cometic makes custom head gaskets but I believe they are pricey.

 

[grjammer]

Cometic sells a bore size of 4.040 for head gaskets.
You could order custom gaskets, they make to order anyway.
They do stock a full top end gasket set with 3.93 bore size head gaskets included. I would personally not use the smaller bore gasket, but use the 4.040 gaskets available separately. Still pricey.
Seems like the 4.180 is huge difference, but Felpro lists those 8553PT as stock 318 gaskets. I am not a pro by any means, hopefully others will chime in. You may have no issue.

 

[Syleng1]

I've had great results with those gaskets. If you search for a smaller bore size (fire ring) the options are limited. 65

I too have had good results with them for stock or in this case mild cylinder compression increases.
I’m not sure how much that gap decreases compression. Or creates hot spots or burnout of the gasket.
I was hoping RRR would give his backwoods logic. lol!

 

[dano]

I believe they are thicker than the 1008 like 0.054" compressed vs .039". Those numbers probably can vary a few thousands.

 

[Newbomb Turk]

Send it. Thousands and thousands went out with those gaskets and it’s not an issue unless you are fighting for compression or you are trying to beat every last hp out of it.

 

[B3422w5]

Heck, the 1008 is 4.180 bore, and probably 90% of guys that use it( like me) run it on 4.08 bores, or smaller. So I would run it and not think twice about it.

 

[Syleng1]

Heck, the 1008 is 4.180 bore, and probably 90% of guys that use it( like me) run it on 4.08 bores, or smaller. So I would run it and not think twice about it.

Thanks! Just me over thinking it I guess.
I’ve run that gasket before with success. It’s only a van with 3.00 gears.

 

[Syleng1]

Send it. Thousands and thousands went out with those gaskets and it’s not an issue unless you are fighting for compression or you are trying to beat every last hp out of it.

Your right. Surprised RRR has not joined in yet.

 

[Syleng1]

I believe they are thicker than the 1008 like 0.054" compressed vs .039". Those numbers probably can vary a few thousands.

The set I used on that engine before compressed was .038. Same felpro number.

 

[oldkimmer]

U also have to check them against the cylinder head. You’re fine with those gaskets but a smaller bore gasket sometimes doesn’t cut it. Kim

 

[volaredon]

Ran into that on a /6. Milled the head and ("just") cleaned up the edge of a couple of a couple of combustion chambers on the head and laid a stock replacement fel pro gasket, a ROL and a Detroit brand gasket I have here on the head and the fire ring overhung the CC on the head but not on the block... I ended up with getting the Aussie HG as it had a bigger bore.

 

[George Jets]

Here would be my choice on the overbore .030 318, head gaskets.

Mr Gasket 1121G
Small Block 318/360
.28 ths compressed

Advertised as good up to 11:1 cr.

Smaller diameter fire ring as compared to the felpros.


☆☆☆☆☆

 

[Newbomb Turk]

Here would be my choice on the overbore .030 318, head gaskets.

View attachment 1716462164

Mr Gasket 1121G
Small Block 318/360
.28 ths compressed

Advertised as good up to 11:1 cr.

Smaller diameter fire ring as compared to the felpros.


☆☆☆☆☆

I had a set not seal on the dyno a couple of months ago.

I’ll never use them again. Never even fired the engine.

Filled the engine with water and they leaked externally.

Everything was flat.

 

[Syleng1]

Here would be my choice on the overbore .030 318, head gaskets.

View attachment 1716462164

Mr Gasket 1121G
Small Block 318/360
.28 ths compressed

Advertised as good up to 11:1 cr.

Smaller diameter fire ring as compared to the felpros.


☆☆☆☆☆

Thank you!