604 Crate Motor

What can and cant you do to a 604. What can you legally change? What cant you change?


Doug, Nothing in the rules one way or another.
no way to tech. just a bad rule.
jimmy wilkins


Is A dale giving the weight break?

This is the GM performance parts circle track crate motor tech manual. It should have everything in it that you need to know about what you can “legally” do to a crate motor.



Doug , I asked this question in 2007 before I build a motor for my modified and was told at that time from Rex, there would be no weight break. don’t know if that has changed…Just a bad rule for modifieds.
P.S. 604 crate motor max rpm is 5800.
just saying’

2008 Auburndale speedway owm champion.


I agree 7lb per cubic inch is all the rule we need. Crate motors are bending rules. Thanks for the good info Mr south

Kinda like a catch 22 Doug, all rules say you can run it with a weight break but no other words of that you have to leave it alone, on the other hand if you read the rule as it says, 604 crate ok, that would mean technically if you changed one thing it is not a 604 crate anymore, right? Just have them look at the sealed bolts, bad thing is you can buy them, make sure it has plastic timing chain cover, right casting numbers on the head, check cam spec etc. granted over a long run 100 pounds makes a difference on the tires. By the way at Showtime there is no weight break, or Desoto


I found some very interesting things in the manual that Mr. South posted. A certain number of bolts from each major component have a laser etching ? A square? Wonder if the cheater bolts have went to that extreme? There should be no weight break anywhere in our class for Crates. 2500 lb minimum. Then there would not be a grey area.