Can you use other SB heads on them! Are there any caveates! I read something about needing 'steam holes' to be drilled.
hi-ling,
Aug 3, 8:20pm
Yes most early heads will fit, but be aware of different combustion chamber sizes, you dont want to raise your compression ratio too high. Steam holes are recommended for all 400 block applications (GM blocks only). Use a 400 Gasket as a template and drill the three holes, nearest the spark plug side of the head, straight down. The other three which are very near the head bolt holes should be drilled at a 30° angle away from the bolt hole. The center hole will intersect water about 1" down and the two outboard holes to a depth of 2 1/4". Use 1/8 drill.
blackcat17,
Aug 3, 10:24pm
Thanks for that. Are there standard chamber sizes for the different motor sizes or is it a bit more complicated than that! Anything to look out for! Looking to help a mate out and see if we can find some heads for his 400 to get it going, his are apparently stuffed, corrosion related.
hi-ling,
Aug 4, 10:04am
Most 400 heads are 76cc chambers. If your wanting around the same comp ratio, look for 350 heads from around 1970 thru to mid 80's casting number 333882, they are mostly 76cc chambers and flow not too bad, These are probably the most common heads you'll find. if you want a bit more compression, then look for some heads with around 70cc chamber, llike casting number 3927185.I wouldnt go smaller without a cam change with a bit of overlap.
blackcat17,
Aug 4, 10:50am
Awesome, thanks for the advice.
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