Fast Idle RPM'S ?

1STMP

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Hey all, at a loss as this is my first big block
Mopar build.
What should I set the fast idle rpms to.?
The factory settings on the 750 cfm quick slayer
put the rpms close to 2000. To my ear, this sounds
way to high, and I'm getting slight lifter rattle on
cold start. The 440 is basically stock, w/50
psi cold. Cam is 230/230 at .05/480 lift/109lsa.,
727 trans, 2800 stall conv. Warm idle- park-= 900
rpm/in gear=600rpm. This engine is barely past
break-in and has not been driven as of yet.
Thanks in advance for your valued input.
 
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66Satellite47

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IIRC, I'd set it in the 1500 RPM range. That should be enough to keep it running.
 

72sunroof

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Hey all, at a loss as this is my first big block
Mopar build.
What should I set the fast idle rpms to.?
The factory settings on the 750 cfm quick slayer
put the rpms close to 2000. To my ear, this sounds
way to high, and I'm getting slight lifter rattle on
cold start. The 440 is basically stock, w/50
psi cold. Cam is 230/230 at .05/480 lift/109lsa.,
727 trans, 2800 stall conv. Warm idle- park-= 900
rpm/in gear=600rpm. This engine is barely past
break-in and has not been driven as of yet.
Thanks in advance for your valued input.
Fast idle rpms are set warm. When you start it it will take time to get there when it gets there it is warmed up. No harm in 1800 rpm fast idle it just speeds up warm up.
 

Ron H

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Have mine set at 1200 RPM fast idle. Old school tips from old mechanics..
 

440+6

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1200 fast idle, never for long becouse I'm driving within 5 to 10 seconds later, never stalls either.
725 for low idle, 440 six barrel.
 

Don Frelier

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The 300 rpm drop into gear seems a bit high?
I would think it should be around 1/2 of that or maybe 150 RPM.
Have you done any tuning on it?
Try a higher initial advance if you haven't already like 15-20 Deg. BTDC.
 

Nate S

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2000 seems high. There’s no real “right” here. Depends on what you want. I never even bother with a choke, I start it and hold it around 1200 for half a minute then it idles at 750 after that. I guess if I had a choke I’d aim for about the same. Like you said, it’s not a huge cam so it shouldn’t need a whole lot.
 

Billccm

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Ol'Richard Ehrenberg recommends 2000 for what it's worth.
 

Jc cooper

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Not convinced that a cold engine should run above 11or12 fast idle , mine likes 850 rpm warmed up with my set up !
 

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