[Mike S]

I am going to lower compression on the race car over the winter. Need opinions.
I will be freshening the engine. Right now I have 72cc e-heads that flow 330. With the flat top pistons I have 12.0-1.
I can get 15cc dished pistons that will get me to 10.8 or new hi port heads (that flow 360) that will get me to 10.8 or new e-heads (that flow 340) that would get me to 10.4.
What do you think would be the best way to go?

Right now the car will go low 9.6. But I detune it to go 10.0. I still want to go 10.0 in the summer. Getting hard to slow it that much in the fall. Also want to drive it more on the street with pump gas.

[steve25]

In your situation since any of those combinations will provide the power you need to run that time it comes down to cost.
Is a set of new ready to drop on heads cheaper then new piston, rings and a re-balance job?

Oh, and you may want to add to the cost of the piston swap new rod or main bearings depending on how things look when you get it torn down.

[mgarblik]

Car will run great at 10.8 compression on pump gas. Like Steve mentioned, the one piece if missing information is the condition, age, #of runs on the short block. Without completely pricing it out, it seems the cost would be lower installing new pistons. Or possibly having a dish machined into your current pistons if the short block is excellent and put it back together. Weigh a piston before and after cutting to determine if a re-balance will be necessary. You might be surprised.

[AG]

I'd get new pistons and have them made to the same weight as your current pistons so you won't need a rebalance.

[PAUL K]

If it's a factory block I'd stay with the Edelbrock heads. If your pistons are in good shape you may be able to dish them enough to reach your desired C.R..

[Tim Corcoran]

Not sure why you would want to buy new pistons if they are in good shape. Much cheaper to have a dish machined and, like was mentioned weigh a piston before and after machining to see if you even need to do a re-balance. Now if the bore is worn out and you need an over bore then I would get pistons.

[Stan Weiss]

Originally Posted by PAUL K

If it's a factory block I'd stay with the Edelbrock heads. If your pistons are in good shape you may be able to dish them enough to reach your desired C.R..

Paul,
Do you believe that some over balance is not a problem?

If so, and he has room to dish his piston. Do you think he would be OK without re-balancing?

Stan

[b-man]

Some lightweight flattop pistons won’t have enough crown thickness to accommodate the dish volume necessary so that’s something to be considered.

[PAUL K]

Originally Posted by Stan Weiss

Paul,
Do you believe that some over balance is not a problem?

If so, and he has room to dish his piston. Do you think he would be OK without re-balancing?

Stan

Hi Stan, with the RPM range he's turning I wouldn't over balance the rotating assembly intentionally. However most likely the amount of weight removed from the pistons wouldn't necessitate a re-balance and create a slight over balance scenario.. Three CC can be removed from the head and increase performance. If you're really picky about matching the existing weight, one could look at wrist pins, locks and a heavier ring pack.

[Skip Fix]

Are you sure they measure 72cc? Many are closer to 75. What sized intake valve? you can clearance the chamber around it using a head gasket and even unshroud the valve some