604 Motor, new to Dirt Late Model racing

[Doug Riparetti]

I have never raced a Dirt Late Model and I just bought one. I put in a new 604, I was not aware of all of these web sites and I keep reading about the motor issues, I am a bit concerned. Is it because of excessive RPM’s or just poor motor design? What RPM are you running? What RPM should I run? The recommended 6200 rpm, I put in a 6400 rpm chip? I am running the car for the first time next Friday and there are no other 604’s at this track, just 1 guy with a 602. HELP!!!!!!!!!!!!!!!!!!!!!!!!! Sorry about the post aboveon the other topic section

[Chris Steele]

Yes there has been a ton of valve train problems with the 604, including myself. Doug, I have come to believe the problem is mainly the RPM's we were turning them. Most people around here are turning them 6700-6900 RPM's every week. The valve springs are not strong enough for those kind of RPM's, so the lifter actually "ramps" up off of the cam lobe. When the lifter “lands” backs onto the cam lobe, it is causing severe harmonics within the valve train. Now another problem I have seen with the 604 is the valves are too soft and the keepers will begin to dig into the valve stem. Now if you turn yours 6400-6500, it might not dig into the valve stem as bad. One guy around here says he turns his engine 6400-6600 and has had ZERO problems and YES; he is winning races with it. Matter of fact, he has won about 3 in a row now at three different tracks. We just decided to go back to the 602, turn it 6400 and forget about it. You should be ok with 6500 RPM's.

[Doug Riparetti]

Thanks for the response, I am out here in California, and they are just beginning to go with the create motors at this track, so there really is no one to talk to about this

Thank you

Doug Riparetti

[Chris Steele]

Doug, feel free to email me or call anytime you wish. I will help you if I can and I will tell you if I can't instead of misleading you.

steelesauto2@comporium.net
(803)325-2995 9:30am-5:30pm Eastern time

[Doug Riparetti]

I put you in my data base, thank you and I will be calling/e-mailing, I know I will need some help

Doug