Help with QF HR-750

JamesRR said

I sprayed and checked for vacuum leaks. No rpm change when sprayed. I believe this is my cam.

http://www.summitracing.com/parts/cca-20-672-4?seid=srese1&gclid=COrRo-X8q70CFafm7AodIEEAog

My problem is I have low idle because if I turn in the idle speed screw too much it is exposing too much of the transfer slot and thus not running off of the idle circuit. Vacuum is very good in all other ranges. Is a .508 small in a small block street car?

best,
James

Click to expand...

I had the old version of that cam in a 360 years ago. I had a hard time getting it to idle well too. I finally got tired of messing with it and locked out the timing at 34 degrees...after that it worked great and was very responsive. You are correct, In a 340 street car that cam is on the big side (my bad, I was thinking you had a 4" crank for some reason).... I have a tendency to see things a little differently because I race my street car a LOT, and I put up with my car not having the best street manors for the sake of power.

Oddly enough, my cam has the same duration as yours, but it is in a stroked small block and it is a little too mild for me....but I'll be fixing that soon enough. My motor pulls 12" of vacuum at idle with the timing locked at 34°. I'm not saying it is right or wrong the way I have my car set, but it works for me. It makes the car behave well enough that I can drive all over on the street and lay down mid 10 second runs at the track.