Technical 305 steel head gaskets

I pulled the heads off my '86 305 and found steel head gaskets.

The gasket bore is about 3.82(ish) and they're about .018" thick. For the life of me, I can't find a supplier that has gaskets with those dimensions.
If the bore is correct its too thick,... if the thickness is right, then the bore is 4.1"

I even phoned a GM dealer and the parts guy said their listing for the sbc head gasket covers both the 350 and the 305. But, isn't a 350 a 4" bore?
How can one gasket work for both engines? Isn't there an issue if the gasket bore doesn't match the cyl bore?

 

"Suitable replacement for obsolete GM part number 3995633" http://scegaskets.com/store/chevrol...askets/steel-shim-head-gasket-for-sbc-511961/

 

It's common practice for gasket makers to make them to fit the biggest bore in an engine family, so that they only have to make one gasket instead of one for each bore.
It's a crappy way to make gaskets, it seems. I search out early NOS gaskets to avoid this.

Hey, that's a good find from Johnny Gee. The price is good, I'd buy a couple sets, before the supply dries up.

 

most guys just use a thicker composite gasket...

 

Johnny, thank you so much!! Ordered a pair as soon as I read the parts description.
Thats what this community is all about...rodders helping rodders.

 

I search E-Bay for steel shim gaskets. You can also search marine applications. Most SB's came with steel shim gaskets from the factory, but why they're not available to the public is really strange. I do have several sets for my under 4 inch bore motors. I am Butch/56sedandelivery.

 

From the factory the heads,and block are as flat as they ever get.Out in the world guys surface heads during repair,and not the block.Composite gaskets allow that to work.

 

Sure hate to use 4" head gaskets on a 283 with 3.875" bore...What happened to all the 283s? (joking)

 

I use the 305 gaskets on the 283 builds. It's the closest thing to the original. When you are running small cubes every CC counts. A lot of guys buy a set of 462 casting heads and coupled with a new composite head gasket and their new performance heads just netted them a whopping 8:1 compression ratio.

 

Watch E-Bay for 262 V-8 (NOT the V-6 engines), 267, and 305 SBC engine steel shim head gaskets. They pop- up frequently, and another source is marine applications. That's what I do, and I have a fairly decent supply of steel shim head gaskets for my 265/283 projects, and usually, a lot cheaper than SCE Gaskets! It's your money however. I am Butch/56sedandelivery.