what head gaskets? '67 283 motor and 305 heads

[knightowl73]

Im putting some '87 305 truck heads that I already have on my '67 283 motor with stock flat-tops in it but im kinda stumped when buying the head gaskets because I heard that I could use the thinner shim gaskets to bump up the compression a bit, but then there are 305 specific gaskets.....

So what do I buy? will the shim gaskets still work for me with 305 heads? isnt it something with the cooling passages thats different? cant remember and damn sure dont wanna run it hot. but do 350 head gaskets work on 305 heads and motors without cooling issues?

i wanna run the shims, but if i have to run the 305 specific gaskets i will. cant find any 305 specific shim gaskets, guess they arent that popular

[knightowl73]

damn no one has input on this?

[BB4ME]

use the 350 shim gaskets should be fine not really gonna have a noticeable compression increase though

[knightowl73]

thanks,
i figured every little bit helps. its a 283 going into my truck with the 4.10 gears and 400 tranny. could get interesting if i do it right. plan to do a cheapy valve-job myself since im replacing cam, lifters, and valve springs. prolly gonna gasket match them too and the eddybrock intake too if need be. figured the shims were the least i could do for compression since its a budget build and the motor has stock flat-tops. i would have made a better head choice but i already got them so their gonna get used.

[rfmaster]

Assuming that you have stock 283 flat top pistons 'some' stock 305 head gaskets should work, but there are several things that you should consider before selecting HG for your application as HG bore must be larger than your block bore or it will not seal properly! In the past 350 HG were used on 283 (usually with HG bore of 4.060), but if you are willing to try you may pickup a bit of compression as certain 305 gaskets may do the trick - see below. You have to measure your block bore (unless already known)

Note that
283 blocks have 3.875" standard bore, +30 3.905"
305 blocks have 3.736" standard bore.

305 Head gasket, compressed, CCs added
Manufacturer # Compressed Thickness Bore Added cc
CARQUEST 5745 .027” 3.839 5.12CCs (DO NOT USE on 283, HG bore size is too small!)
Felpro 8510PT .041” 3.900” 8.0CCs
Corteco 55061HG .028” 3.870” 5.1CCs (DO NOT USE on 283, HG bore size is too small)
Victor 5745 .027” 3.839” 5.12CCs (DO NOT USE on 283, HG bore size is too small)

A slight bump in compression could be expected, but other variables such deck height, piston relief volume should be taken into account. 350 HG is a safe choice.

//RF

[knightowl73]

ok thanks for the input