604 that wont turn more than 6000?

[car23]

Bought a used 604 that was a winning motor. I finally got the car free enough to get the bog out of it but it doesnt seem to like turn over 6000 when in racing conditions. It runs fine and is very responsive and plugs look good. Would the valve springs have fallen off that much to cause this? One track i run everyone else is running a 5;95 gear and im running a 6:25 with the same tire combo.

[Egoracing]

Bought a used 604 that was a winning motor. I finally got the car free enough to get the bog out of it but it doesnt seem to like turn over 6000 when in racing conditions. It runs fine and is very responsive and plugs look good. Would the valve springs have fallen off that much to cause this? One track i run everyone else is running a 5;95 gear and im running a 6:25 with the same tire combo.

Yes, check the springs.

[jedclampit]

And valve adjustment.....and ignition timing.

[eiland29]

are you sure your running the same ring - pinion they are o compare gears

[car23]

yep same gear

[rubbinsracin]

you might have the same set of gears that you can change at the track, but do you have the 4.11 or 486 Ring/Pinion? because it sounds to me, if you are giving up that much RPM, you might have the 4.11 w/ the combo of the 6.25. if you are running what you think is a 6.25 in a 4.86 r/p is a 5.30 in a 4.11 r/p. that right there would give you the difference you are seeing right there.

if you just put it in neutral, and put like a 6200 chip in it, will it rev past 6k? i know you dont want to do this alot, but if you try it 1 or 2 times it should not hurt anything.

[car23]

i have a 4:86 i set up diffs alot so im sure about mine ive had this rearend since 1998

[DIRTRAYCER]

I cant imagine that your springs would cause you not to be able to turn more than 6000 rpm ! *I would not recommend either of these things*, but I know a guy that ran over 20 races on a set of springs and then the Track checked them and they were weak compared to others and he had No Problem turning his above 6800! I first would check out my Tachometer . Then maybe check timing . We changed Carbs and nothing else and had an RPM Drop of over 250 rpm. You may have to run a different gear than some other guys. We are running like 40 points different than a friend of ours we run against and he turns the same rpm.

[car23]

Tach recall is off exactly 1000 rpms everytime no matter what rpm you pull it. I checked it last night. Had the revlimiter set at 6800 so it was showing 5800. Turned up revlimiter and ran it last night and it was fast but the last 5 laps it started getting flat. I think the ignition system may be getting hot.