What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

what size head gaskets for a bc 350 bored 40 over?

Kain

Kain

3/4 ton status
Joined
Mar 16, 2011
Posts
5,725
Reaction score
2,141
Location
Lubbock Texas
Like title says I have a 350 bored 40 over with eddy aluminum heads
what gaskets material? What Size/Thickness do i get ?

it has been a while and i dont remember what i used when i built the motor
 
FWIW GM used the steel shim gaskets from the factory. They are apparently harder to make and keep a seal if the deck and heads aren't perfectly flat, but you know they wouldn't make a mistake like getting quench wrong.

"Spec" for deck (compression) height is .025", so .015" head gasket gets you to "best quench" assuming the compression height is near spec.

Couldn't check earlier, not many options based on what they list as compatible.

I recall when I was last looking at putting a SBC together the steel shim gaskets were much harder to find than the ones that are wrong with stock deck height. I have no idea if zero decking is standard on a rebuild or not.
 
Do not use the Fel-Pro head gaskets that have a steel sealing ring around them with aluminum heads. Those steel sealing rings will damage the surface of soft aluminum heads.
 
Which if you enlarge the picture, you can see that these are just Felpro 7733-PT2 permatorque head gaskets.. I figure if Eldelbrock specs them for use with their heads, they must know what works best..

I used them on my performer RPM heads when I bolted them on,,no issues so far.
 
well i have a test kit coming, and should give me an idea if its head gaskets just put number 1 on tdc and see if she leaks and if she does i start tearing her down right then and there, be a week or 2 before i can afford gaskets anyway


https://www.ebay.com/itm/113424763254
 
crap its got a blown head gasket at least. when i put the leakdown tester to it was like blowing bubbles out the chocolate milk when i was a kid out both radiator and valve cover :angry1::angry1::angry1::angry1::angry1:
 
yeah, that's not good...did you pull all the plugs ?
you may be able to hear it blowing to the cylinder next to the one you're testing..
Not that it makes a difference at this point...
head still has to come off...:frown1:

you might want to use a beam type torque wrench when pulling the head bolts to see if there is a pattern to some loose or stretched bolts..:thinking:
 
Was going to mic head bolts (there are) but. First finish the test
Then do the rest of the cylinders 3,5,and 7 then go from there
 
dyeager535 said:
I want to say ideal quench is considered .040"? Iirc, it's why the most common head gaskets are in that range, zero decked gets you near perfect quench.

Without decking the block, the steel "shim gaskets" are generally the only way to keep quench in a decent range.
Click to expand...

Just think of all the people using those gaskets, who have hurt performance, and efficiency and not even known. I was discussing this exact topic with a friend a while back, talking about all stuff we just threw back together with those gaskets, and never thinking about it. Oh well, way she goes.
 
You must log in or register to reply here.

Latest Posts

Top Bottom