higher compression

[sho4life]

How much can you mill the sho heads with stock pistons if this is even possible. And how much more compression will it yield? Just wondering since i have to take off my heads to change valve stems seals anyways. Also will the bigger valves make any more power with the stock cams? And maybe porting the heads or do they flow enough as they are stock?

 

[Lorenr]

Do Not Mill Heads

Never mill these heads or the timing belt will lose the relation ship with the crank and the engine timing will be affected. Very bad and the heads are ruined.

The best way to add compression is with pistons having a larger dome. Another way is to weld up the combustion chamber in some areas, but this requires considerable effort and knowledge concerning re-contouring the chamber. The re-contouring of the chamber could make more power.

:swing:

 

[SeanMc]

You can go down a couple 1000ths, but Lorenr's mentioned solution is the best way.

 

[NovaSS]

Yep anything more then a clean up cut is a waste of time, Pistons, custom head gaskets or chamber work is needed to increase CRs. Out of all options pistons are the only cost effective choice.

Large valves help but only if done with a proper multi angle valve job and by some one who doesnt sink the valve to far down into the seat.

 

[rubydist]

just to provide so specificity to the milling question -

if you do the math you will find that every .020" removed from the head retards the cam timing approximately 1 degree. more than a couple of degrees of retarding cam timing will be detrimental to the performance of the engine.

if you run the atx accessories, you can tweak the size of the front side idler to recover this cam delay. since there is no such idler on the mtx accessories, you can't fix it that way if you have mtx accessories.

 

[Jh8990]

just to provide so specificity to the milling question -

if you do the math you will find that every .020" removed from the head retards the cam timing approximately 1 degree. more than a couple of degrees of retarding cam timing will be detrimental to the performance of the engine.

if you run the atx accessories, you can tweak the size of the front side idler to recover this cam delay. since there is no such idler on the mtx accessories, you can't fix it that way if you have mtx accessories.

good to know.