just got a quick question. my idle in gear is about 600 rpm and in park or nurtral it goes to 1000 rpm. how do i bring down only the idle in N and P? i alway thought they were connected, guess not. anyway its a holley 750 VS. also is 600rpm to low?
thanks
jason
thanks
jason
Senior Member
Can we have a little more info on your engine combo please. I have a built 355 in mine and that sounds about right on both ends.
Supreme Member
F-BIRD'88
Supreme Member
close
May 23, 2023
Check the ignition timing while idleing in gear and while in neutral.
If the timing increases while in neutral as compared to "in gear"
then the idle speed will jump up.
For best results on a mild to moderate cammed street driven car
the advance curve should not start to advance till 1200/1400 rpm.
Be sure the vacuum advance is plugged into "Ported vacuum"
not full manifold vacuum on the carb.
The "lightest advance springs" from most advance recurve kits will cause just such an irratic idle. The timing jumps all over the place at idle. A more moderate timing curve with more initial but the same total all in by 3200/3500 usually works better overall on the street than a real quick curve all in by say 2200/2500 rpm.
The larger the camshaft , the more the idle will drop when you put it in gear. Especially with a stock low stall converter. A looser torque converter and lots of initial timing advance will help if you have a radical cam.
Cars with very big cams will run better with the timing "locked out"
so idle timing is 32 to 36 deg and high speed total timing is 32 to 36 deg. No timing advance curve.
You can still use vacuum advance for street driving althou it may need to be adjusted to what the motor likes.
Do you have a large camshaft or nonstock advance weights and springs in your distributor.? Do you have vacuum advance plugged
into "full manifold vacuum"?
If the timing increases while in neutral as compared to "in gear"
then the idle speed will jump up.
For best results on a mild to moderate cammed street driven car
the advance curve should not start to advance till 1200/1400 rpm.
Be sure the vacuum advance is plugged into "Ported vacuum"
not full manifold vacuum on the carb.
The "lightest advance springs" from most advance recurve kits will cause just such an irratic idle. The timing jumps all over the place at idle. A more moderate timing curve with more initial but the same total all in by 3200/3500 usually works better overall on the street than a real quick curve all in by say 2200/2500 rpm.
The larger the camshaft , the more the idle will drop when you put it in gear. Especially with a stock low stall converter. A looser torque converter and lots of initial timing advance will help if you have a radical cam.
Cars with very big cams will run better with the timing "locked out"
so idle timing is 32 to 36 deg and high speed total timing is 32 to 36 deg. No timing advance curve.
You can still use vacuum advance for street driving althou it may need to be adjusted to what the motor likes.
Do you have a large camshaft or nonstock advance weights and springs in your distributor.? Do you have vacuum advance plugged
into "full manifold vacuum"?