# Idle Rpm



## rheckman (Aug 28, 2018)

Hello,
I have a 1970 ram air 3 Manual trans and am wondering where others with same are running there idle rpm
Vac disconnected,
And what base timing at that idle,realizing thats not total timing and other factors .
Seems like all the books show a range other than preferred specific?
Thanks


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## Ebartone (Aug 18, 2019)

rheckman said:


> Hello,
> I have a 1970 ram air 3 Manual trans and am wondering where others with same are running there idle rpm
> Vac disconnected,
> And what base timing at that idle,realizing thats not total timing and other factors .
> ...


I’m running a 462, with a moderate cam (236/242 at .050” 12 deg LSA) and th400. I set my total timing to 36 which results in my base at about 13 or 14 deg - my mech advance is about 22-24 degrees, and I use no vac advance. I use a 2,400 converter so my idle rpm in neutral is about 750 rpm, drops slightly in drive at idle. Ther are lots of threads on timing, but I definitely would start with your final advance and move backward. Your initial timing is a result, not a setting. So I target 36 deg, and adjust timing until I get that timing at around 3,000 rpm where I have all in mechanical advance. Then going back to idle, it is what it is, so for me that is about 13-14 deg, your mileage may vary! Of course all of the above is without vac advance connected. If you use vac advance, that is connected afterwards. Lots of threads on that topic too, in the end it’s your engine and your choice!

But remember your idle rpm really depends on a lot of things, which is why I mention the cam duration and LSA. A very loopy cam will require a higher idle rpm to not stall. Also if yours were an automatic, you would care about your torque converter stall speed for the same reason. On the other hand, too high an idle rpm increases likely ness of dieseling when you turn off. Some cars need as high as 1,000 rpm or higher to idle satisfactorily. But a stock engine should ride around 700 or so. 

Hope that helps!


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## geeteeohguy (Feb 2, 2008)

Idle rpm is always set with the vacuum advance connected. For your car, it can be anywhere between 500-800 rpm, with the specs being around 650-750.


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## Ebartone (Aug 18, 2019)

Definitely GTO guy, I was talking about timing as a separate topic from idle RPM. As you said, at the end of the day if you use vacuum advance, it will be plumbed when you set your final idol. Thanks


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## rheckman (Aug 28, 2018)

Thanks,
Timing with vac plugged the idle goes down,still use the same btdc number?
This quadrajet has only manifold vac.


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## PontiacJim (Dec 29, 2012)

rheckman said:


> Thanks,
> Timing with vac plugged the idle goes down,still use the same btdc number?
> This quadrajet has only manifold vac.


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## rheckman (Aug 28, 2018)

PontiacJim said:


> View attachment 155034


Got it thanks


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