Shavin the Heads

[3100gagt]

I have the heads off my 99 3400 geand am and i am looking to get them shaved and was wondering how much can be shaved off?
With stock cams and pushrods?
20-25 40 thouthands?

[CARS GONE WILD]

shaving the heads will reduce compression, less compression means less power. i thought a tech should know this.

[DomestikDemon]

Shaving heads will increase the compression. If your such a tech yourself, you would know this.

The only thing about shaving the heads though, is that with hydraulic lifters, they are designed to operate within a certain range of play. Shaving the head will bring the rockers closer to the cam, which may cause knocking or even a bent pushrod. Our cars dont have a valve lash adjustment, so it kinda limits how much the heads can be milled.

20-25...I wouldnt go too much over that if I were you.

[Bart001]

When I did my engine, I milled my heads 15 thou, and I ported my heads.....
Put the 3400 top end, on my 3100 rebuilt bottom end, with new pistons, rings, bearings etc........lol....

Actually........ they say to take 20 thou off MAX... thats it....
AND on the Block they say you can take i think 10-20 thou off too

I'm thinking that you can go like 30-40 off the heads........
BUT thats just thinking outloud... dont do it unless your an engine builder like me... and are willing to do your own checking with putty first......
Your only concern with milling the heads is... Valve to Piston Clearance...

Cause if your an engine builder like me, you'll know that you can take up to 250 thousants (0.25") off the heads if you do it right ;) lol..
But that requires some knowledge and Cash...lol.....
And if your REALLY going for power... you wanna weld a 0.25-0.5 inch plate on your heads with all the right holes and ports... Then get domed pistons with gas reliefs, Copper head gaskets, and go to work....lol.....
Goooood LUck man

[3100gagt]

yea i dropped the heads off on fri. to have them take 20 thou off. that is what an machine shop told me the limit was so.

[slowbird]

20 Thou is fine to take off. A good balance between a SAFE amount and a nice performance increase.

Isn't 250 thou = 25 hundredths

[sudden_impulse]

Don't you also want to machine the intake so it all lines up nicely? I know after milling the heads sometimes people have issues matching their intake up to them. Bart, he didn't say anything about you. If the machinist said 20 thou is the limit he might only be willing to go to that point also so he doesn't risk damaging anything.

[Bart001]

yeah... 25 hundreths... or quarter inch.... or 2500 tenthou....
I try to relax....lol... but I mean really..... If your information has to come from others cause you dont know anything yourself... You really cant have an opinion...lol...

yeah that kid said "you dont know what your talking about and that I shouldnt give my two cents worth..."
20 thou is the GM reconditioning guide limit.....

There's really sooo much you can do to this engine.... or any engine for that matter... just gotta know what your doing....
I mean you can weld plated on the heads to increase chamber size...
Domed pistons.... Radical Cams... You can even go back to a distributor cap, and Carburator..... I was about to do that, but didnt wanna spend the cash in customizing my lower manifold...

[TA^Guy]

Originally posted by CARS GONE WILD
shaving the heads will reduce compression, less compression means less power. i thought a tech should know this. ??? Shaving the heads will reduce the combustion chamver size, thus incressing compression.

[1CoopGT03]

Hey Bart I hate to disagree with you but theres no way you should be taking a 1/4"= .250" off of the heads and or the block . And yes I have built my fair share of engines also. You take off a total of a .5" and you are going to have all kinds of problems. The numbers should be around .025 to .040" .

The lower intake should be shave the same to match up. Also 3100 you may want to look into getting slightly shorter push rods . Back in the day my friend & I built up a Dodge 340 . Had the heads milled & the block decked . We forgot about the push rods . We kept breaking rocker arm shafts till we figured out the push rods were to long. At least we didn't break anything else.

[TA^Guy]

Cleaned up and back in bussiness.

Enjoy. :D

[TDRDevelopment]

Also, if your gonna deck the heads you should deck the block as well or you could run into head gasket sealing issues. Its just a good idea to make sure the block deck is square with the newly squared head. You gotta watch out with intake too. It might not fit when you go to put it back on. It may have to be machined.

[ChevelleSSLS6]

Originally posted by CARS GONE WILD
shaving the heads will reduce compression, less compression means less power. i thought a tech should know this.

We should double stack head gaskets to get more power through less compression. lol...:roll2:

heck I mill .020 off briggs heads with a belt sander; make sure its straight and all and it adds a little balls to the thing. lol... more compression makes power, but you'll likely need to use premium fuel.