A few Jet sizes made a difference

[will e]

401 with holley truck avenger and edelbrock dual plane.

My rig is now emissions exempt. I haven't done anything to the tune in years because once it passed I didn't want to tinker with it.
But now I am messing with it. I found the power valve was leaking and replacing it took away the almost constant off idle stumble and occasionally dying.
But even after fixing the power valve, adjusting the accell pump and increasing the advance on the timing it would still occasionally hesitate off idle.
A long time back I put in 61 primary jets for one of my annual trips to Ouray and since it passed emissions with these jets, I left them in.

I swapped the 61's with 64's a week ago and since then I have had zero instances of any hesitation/stumble off idle. I shouldn't be surprised a small change like that would seem to have eliminated a problem, I am just happy it did. The jeep hasn't been this 'drivable' in a long while. And I am loving it.

[BaldBeardedBastard]

That's great to hear! Have you noticed any change across the RPM range with the re-jetting or just the idle stumble?

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[1978J10REDWHITE]

One thing you might want to always do is use a vacuum gauge to achieve as much manifold He as possible. That helps the air-fuel emulsification step off idle.
Can be accomplished by two way, actually three.
A cam with 112 to 114-LSA for best manifold vacuum numbers, adjust the timing, and the idle fuel ratio mixture adjustment.
Invest in a gauge and play around with it some.
A loose timing chain will always cause sloppy wandering numbers IF it is loose.

[will e]

That's great to hear! Have you noticed any change across the RPM range with the re-jetting or just the idle stumble?

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Not much change overall. I am still working on tuning it for more power. Cruise vacuum went from 17 to 18, so a slight improvement.
I have my initial timing at 8. I am going to swap out the plugs before I increase the timing again. I am hopeful to get highest vacuum around 12 initial with no pinging.

[will e]

One thing you might want to always do is use a vacuum gauge to achieve as much manifold He as possible. That helps the air-fuel emulsification step off idle.
Can be accomplished by two way, actually three.
A cam with 112 to 114-LSA for best manifold vacuum numbers, adjust the timing, and the idle fuel ratio mixture adjustment.
Invest in a gauge and play around with it some.
A loose timing chain will always cause sloppy wandering numbers IF it is loose.

I've been working on it with a vacuum gauge. I am making small adjustments and logging the changes. After replacing the spark plugs I am going to start increasing the initial timing to see how much vacuum I can get.

My plan is to install an AFR gauge to fine tune it. I am going to swap out the manifolds and when I do I will have the exhaust shop install the bung for the sensor. Then I can really get a good read on the right jets at cruise, the best idle mixture and use the vacuum to help decide on the best power valve too.