Head gasket selection

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Daca214

Daca214

G-Body Guru
Dec 1, 2017
645
93
Jupiter, FL
Hey guys quick question. I just discovered my olds 307 was bored .040” according to marking on pistons

How can i select the proper head gasket? I cant seem to find anything on fel-pro other than the stock selection. Will that work?
 
pontiacgp

pontiacgp

blank
Mar 31, 2006
27,777
113
Kitchener, Ontario
The 350 I have is .030 bored and I just changed the heads this year. I used the stock Felpro head gaskets.
 
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bracketchev1221

G-Body Guru
Jan 18, 2018
624
93
Usually the replacement head gaskets are made to accept a large overbore and are made to fit the cylinder head chamber. For example, the big block chevy replacement gasket is 4.37 on a 4.25 bore.
 
olds307 and 403

olds307 and 403

Geezer
Oct 14, 2008
5,879
113
Melville,Saskatchewan
Yes, the Felpro is the only currently available gasket available for the 307 that I know of. The 260, 307 and 403 have unique head gaskets due to oddball bore size. The head gaskets changed in 1977 and up motors, a 3A head 350 gasket might work but why even try unless you are going for a huge overbore, which supposedly a 307 can take. How far in the hole do those pistons sit? I know it is just a 307 but it may have miserable low compression and terrible quench.
 
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Daca214

Daca214

G-Body Guru
Dec 1, 2017
645
93
Jupiter, FL
Yes, the Felpro is the only currently available gasket available for the 307 that I know of. The 260, 307 and 403 have unique head gaskets due to oddball bore size. The head gaskets changed in 1977 and up motors, a 3A head 350 gasket might work but why even try unless you are going for a huge overbore, which supposedly a 307 can take. How far in the hole do those pistons sit? I know it is just a 307 but it may have miserable low compression and terrible quench.
I havent checked that yet, but will. I just learned about Quench on Petes Garage on youtube........LOL. This should be interesting
the compression was around 160 all around before i took it apart and found the worn pushrod on #8. i believe the lifter was frozen
 
olds307 and 403

olds307 and 403

Geezer
Oct 14, 2008
5,879
113
Melville,Saskatchewan
Actually 160 is pretty good.
 
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paul.m

Master Mechanic
Oct 20, 2018
363
43
This is also a chance to increase your compression ratio if your interested , i wont try to type out all the per tenant info here but im sure theirs a ton of info on you tube. Just in case you were not aware of that . And fel pro,s will be just fine .
 
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