ways to get compression

[BillyWagoneer]

so im getting into a little more serious motor building. my block however is already 60 over. with about 15000 miles on it i doubt i would need to bore it again. but without doing the bottom end what are other ways to gain compression with at least 9.5:1. the edelbrock heads only give a 360 about 8.8:1. i would be happy with 9.5:1 but am shooting for 10:1. also will be doing a spring valve and rocker upgrade.

[joe]

Raise the CR significantly? Pretty much 2 basic options resulting in a smaller squish area: lower the heads and/or raise the pistons. Yeah over simplification but you get my drift?

[Carnuck]

Find some '71 401 head$.

[BillyWagoneer]

I know I read that they are 51cc but I figured there impossible to find

[Ristow]

you ain't doing 9.5 without pistons. 51cc heads won't even get you even 9.0 with the pistons you have.

[fulsizjeep]

Ristows right.................again

[mdill]

Mickey-Thomson screw on pop-up piston domes.

[J20 project]

Find some '71 401 head$.
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Hmm. Might be a good idea, would require some creative type stuff concerning head bolts. My 71 block takes 7/16in , your 360 takes 1/2in. Might be okay to drill the heads out but I would probably want to talk to someone who has done it. I hybrid ed a set of 396 7/16in bolts for my late model heads and 71 block.


J20

[Woodchomper]

Originally posted by: J20 project
Hmm. Might be a good idea, would require some creative type stuff concerning head bolts. My 71 block takes 7/16in , your 360 takes 1/2in. Might be okay to drill the heads out but I would probably want to talk to someone who has done it. I hybrid ed a set of 396 7/16in bolts for my late model heads and 71 block.

'70 and up AMC V8 blocks use 1/2 inch head bolts. The '69 and earlier blocks used 7/16 inch head bolts. You can put a later head on an earlier block with stepped dowels.

Anyway, the '70 291c heads will bolt right on a later block but will only give about a .5 increase in compression. The 291c head is also drilled differently than the post '74 heads for accessory mounting. That means you will have to fabricate an adapter for the trans kick down bracket and you will be missing a bolt hole up front for your a/c compressor bracket.

Ask me how I know? I'm running a set of 291c heads on my 401. The nice thing about the '70-'73 heads is that they use stud mounted rockers. These heads are not scarce. They usually go for about $100-$150 (rebuildable condition) at AMC swap meets. Where you run into the money is putting in new valves and hardened exhaust valve seats. Ask me how I know...