just cc,d my heads will this be too much comp. ?

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krenzy_84

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Hi I have a set of 1970 U heads for my 69 340 I will be putting in my 72 duster. Just did a cc check and I cam up with 65 CC heads have a stamp on them of 63.4 cc I would assume this was not done at the factory but by a machine shop. I have sealed power L2316 pistons bored 40 over. My question is will I have too much comp. for pump gas with these heads? I know the pistons are factory 10.5 to 1 and that is with 72 cc factory x heads I assume. any knowledge on this will help as I don't want to have a race fuel only engine.
 
All depends on what cam you have.
 
krenzy_84 said:
Hi I have a set of 1970 U heads for my 69 340 I will be putting in my 72 duster. Just did a cc check and I cam up with 65 CC heads have a stamp on them of 63.4 cc I would assume this was not done at the factory but by a machine shop. I have sealed power L2316 pistons bored 40 over. My question is will I have too much comp. for pump gas with these heads? I know the pistons are factory 10.5 to 1 and that is with 72 cc factory x heads I assume. any knowledge on this will help as I don't want to have a race fuel only engine.
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You need to be out of the bore .017-.018 just to hit the factory mark.

Usually you need to be out of the hole a bit more to get the CR up to 10.5:1 like you want. It's nothing to be .040 or more out of the hole.

At 65 cc's you may get lucky and only need to be out .020ish but I'd need to do the math.
 
I haven't selected a cam yet just wanted to make sure these heads won't have too small of a chamber to keep a cr that is manageable. Will be going with a 3000 stall and a 904.
 
I ran my 340 .040 over .020 above deck with a fel pro 1008 .039 head gasket, [email protected] SFT 93 pump gas. I smoothed the chambers and piston valve relief edges, used autolite 65 plugs, and got the tune right. 24* initial 34* total mech, vac advance mid 40s. With a good gear and converter in a light car it's fine.
I now run the same motor with IMM Indy LAX closed chamber heads 63cc with a .060 SCE head gasket.
 
I think you'll be fine with 93 octane. Just put some gear to it and run it.
 
krenzy_84 said:
ok thanks just wanted to make sure I could use them before I spent the time and money on them
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10.5 from the factory was not the a ctual standard CR . So you are not as high as you think.Plus your gasket will thicker than stock and will roughly add 3 to 5 CC's to the volume.
 
Running some numbers, you'll end up around 9.7 SCR with a standard Felpro 8553 PT head gasket, and around 10.0 with the Felpro 1008 head gaskets. With the TC stall you are listing, it sounds like you will have a pretty large cam, so should be OK; just take the normal precautions in tuning up.
 
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