PMO Carbs - Idle Circuit Issue

[Gordo2]

Originally Posted by Geneman

... Are the idle (air) jets you are referring to, the ones that vent to the top of the carb? meaning the ones which will flood the carbs if they are covered over by the mounting plate for filters? I thought those jets normally only conduct air, not fuel...

Yes, idle air jets draw air from the top of the carbs, and the air filter bases have associated holes to to allow the jets (via ports) to access filtered air. Meanwhile, I'm not sure how someone could install the top gaskets or air filter bases wrong without visually noting something is out of whack...

The idle air jets have a relatively large orifice/hole (~0.135mm, about the diameter of a needle) as compared to the idle mixture jets (diameter of a couple of hairs...).

As such, idle mixture jets are the most likely culprit to investigate for a stoppage / clog causing a new hesitation / coughing / low RPM sputtering condition.

Gordo

[Gordo2]

Quick shot at an instruction video for the Colortune.

Comment on taping a penny to the mirror & tossing in the trash is attributed to Mr. Paul Abbott of Performance Oriented who is the carb guru...

[Locker537]

Gordo - thanks for sharing the video. I wasn't familiar with that tool.

[Geneman]

GREAT. But Gordo, what do you adjust to? Is it specified in the CT instructions? Do you want an even blue flame for every cylinder? Which screw do you use to adjust? air, fuel or both. Thanks

[Norm356]

I have the same issue ,pmo carbs on 3 litre s/c je 9.5 pistons 964 cam, msd ignition , runs very strong ,idle jets plug up continually opened up both carbs @ found some white corrosion like stuff in the bottom of float bowls ,cleaned it out ,all was fine .A month later ,it is happening again ,what is going on ? canadian gas ,chevron 94 octane

[Gordo2]

Originally Posted by Norm356

I have the same issue ,pmo carbs on 3 litre s/c je 9.5 pistons 964 cam, msd ignition , runs very strong ,idle jets plug up continually opened up both carbs @ found some white corrosion like stuff in the bottom of float bowls ,cleaned it out ,all was fine .A month later ,it is happening again ,what is going on ? canadian gas ,chevron 94 octane

Norm - my problem turned out to be unrelated to idle jet blockage / debris.

Either way, what are you using to filter your fuel? Seems it may not be sufficient.

I run a Racor 110a and don't have issues idle circuit / jet blockage debris all that often.

Good luck.