heads milled too much!!!

[Scott E. Smith]

just finished putting my 94 R/T back together....but not as easily as it came apart....long story short, it blew a head gasket heads were slightly warped, had them fully machined and block checked for protrusion (ok) used new multilayer gaskets,but when I reassembled, the intake didn't fit anymore!!
had to enlarge bolt holes so it would line up and seal. I think it has too much compression now...somewhat labored starting and runs slightly warmer than before (burped it 4 times to be sure) however seems to have gained some power (quite noticeable!!)the low end I was supposed to loose with the Archer flywheel and headers/exhaust is by no means gone. any input?

 

[Tom Welch]

Scott,

My first concern would be for valve to piston clearance. You should have at least .120" at the exhaust valve.

Did you check the intake for port match? The TOP side of the intake should blend with the TOP of the head. It is a common misconception that the bottom of each surface should be flush, but in fact the top surfaces are of greater importance.

Also, due to the very slim gasket seal on the intake to head, make sure that the mating surfaces are exactly flush or an air leak is possible.

Just my $.02

Tom
Http://btrviper.com

 

[Doug Supercharged Vipers]

Scott -
I'll add some input to Toms great advice....

You do need to go back and check your intake to head port match. If the heads were shaved too much, you can easily match your intake to fit. Although, you will need to remove the intake, a good machine shop can mill the ends of the intake to match the intake ports on the heads. Also, intake leaks can cause a lean-out condition and misalignment can cause a horsepower loss (10 - 30 hp). I would also suggest to check your rocker arm geometry. Stock rocker arms (if your still using them) can change geometry without the ability to adjust them. Side-loading the valves can cause the valve guides to wear prematurely.

If you think you "over milled the heads," the first tall-tale sign will be pinging (detonation) at WOT.

Start-up was normal; Your intake had no fuel in it and the computer needed time to relearn.

Good luck,
Doug

 

[FRANK]

How much was milled off? Usually a quick "cleaning up" of the surface is good enough. Anytime your heads are milled a significant amount you have to have the intake milled so that everything fits and lines up.

Be leary of machine shops unless they have an excellent reputation. I have had my share of problems with machine shops. The last motor I built the shop pressed 3 pistons on backwards...glad I caught the mistake...you basically can't trust anyone...you have to trust yourself

 

[FRANK]

Also if you think you have a vacuum leak put a vacuum gauge on it. If it is low you have a leak. Normal should be 18" and up. Spray some Gumout down around where the intake meets the heads...if your idle rpms go up you've found your leak...