Thread: 396/402 build

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My Dad's got a 396/402 from a 70 Monte. My brother-in-law built the short block some years ago, just been sitting in storage. Supposedly has TRW 2240N Forged Pistons, 9.06:1 CR if used with 106.9 cc chamber heads. These pistons have a 21 cc dome, .181 high. I used an online calculator and figured the deck height would need to be .033" and head gasket thickness of .041". He would like to keep these pistons since they are brand new. My Dad would like to have a pump gas friendly CR of 10:1. Using the calc. I figured up some different head combo, block decking to raise the CR. I know, I know, not the way to set CR. I am typing this all from memory so, I hope I didn't leave something out or get a number really off.
Now my question is, is combo 2 (see below) the better choice due to the quench? I was thinking that combo 1 would be better but, the more I thought about it combo 2 sounds better for the quench and probubly overall performance. With the CR at 9.94 or very close to that, it should be pump gas friendly. Cam profile undetermined other that hyd.


As it sits now:
Piston: 9.06cr with 21cc dome
Head: 106.9cc (piston data for cr)
Gasket: .041" (using calc. default)
Would need .033" deck height

Combo 1:
Piston: Same
Head: 100cc Edelbrock
Gasket: .039 Felpro
Deck Height: .020
Overall CR: 9.47:1
Quench: .059"

Combo 2:
Piston: Same
Head: 100 cc Edelbrock
Gasket: .039 Felpro
Deck Height: .000"
Overall CR: 9.94:1
Quench: .039

Any help appreciated

Keith

just cut the deck used what head you want the iron head s can be cut as well .on the first build i would just take off what you need to get close to o deck .the piston should not be in the hole by .033 .you need real numbers so you need to know that it is if bored it very well could have been deck to . same with heads cutting .033 you could be + piston out of the deck by 008/010 or so with the deck with the pistons hanging out of the deck that not a good way to go with a 039 head gasket you would be less then 030 room with piston rock that getting very close to hitting the heads with the pistons

Pat, in general if you .000 deck the block how much can the heads be cut before the intake has to be done?

Originally Posted by blwn31

Pat, in general if you .000 deck the block how much can the heads be cut before the intake has to be done?

i would stop at 030. with a 039 head gasket