My apologies up front for the vagueness of this issue, but hoping that something may jump out at someone familiar with this sort of issue...

1983 Berlinetta with a new 383 engine. We swapped out an old 305 for the new 383, not sure if the 305 was the original motor or not. Anyway, all is good with the swap and she lights up, runs and drives as expected.

It seems that after running 5-10 minutes, that the idle will mysteriously jump up for no reason. Not a huge jump, but def noticeable It usually happens after we jumped on the throttle a bit, when I slowed down at an intersection, I would notice the engine idling very high with no throttle depressed. Our fix was to quickly turn the idle screw down on the carb to get it back down so she would shut off nicely.

I did notice the same idle increase recently when it was parked and running while we were working under the hood - no one touching anything, the idle just jumps up!

Is this something related to emissions or something else with the 83 Camaro? We've inspected the physical pieces, the throttle cable, the carb plate/return spring, idle screw and spring (it's a new carb) and everything seems to be in order. We suspect maybe a bad distributor or something left unconnected, or connected wrong dealing with vacuum or emissions.

Wasn't sure if maybe there was some computer controlled / early emissions gremlin causing this. Thank you!

 

If you didn't install a new distributor with the new engine it's very possible that the mechanical advance is corroded or worn, causing it not to drop all the way back down on the advance curve. Also if you are going to use the vacuum advance, make sure to hook it up to ported vacuum, so it won't have any vacuum to it at idle.

 

Thank you, great insight. We questioned the stock HEI distributor and will probably replace it. Any idea if this will work with a 1983 Camaro? http://www.summitracing.com/parts/msd-8362

Seems like a generic enough SB chevy MSD HEI but strange Summit stops the application list at 1980 and under. Worried some emissions pieces may be missing.

Good call on the secondaries but I'm thinking/hoping this isn't it since the carb is nearly brand new.

Thanks again!

 

That distributor should work fine.