Quick answers for high HC at idle (1 Viewer)

[pbgbottle]

i usually just drive mine there while in line up pop the hood crank up the idle , do the test drive out turn the idle down and away i go . does sound like the engine is gonna blow when it is reving up around a 950- 1000 rpm also how hot is your engine .if it is running hot it will fail on the hc's also .i usually run mine straight there just make sure the choke is fully off . the only reason they say to bring the vehicle warm is to make sure the choke is off , i also have a buddy with a 454 in a 67 camero . aluminum rad electric fan and mechanical fan . he goes as far as driving straight there .turn off engine . wait his turn .actually pushes the car in the lineup and into the testing facility .starts it up runs the test . and passes , he has a heat issue . if his car sits in that line up for more than 5-10 mins his engine is to hot and fails on the hc's !!! heat will also cause problems ?? just a thought

 

[Pin_Head]

A catalyst for your '72 would be an expensive band aid. Find out what the real problem is and it will pass.

 

[pbgbottle]

if the idle screws don't make a difference and everything else is good . usually need to rebuild the carb don't ya ??. another silly thing i did one time was put teflon tape on my mixture screws and that fixed the problem i guess the screws where worn out or the wrong ones , putting the tape on them sealed the threads better .and i was able to set the mixture on the screws just another thought

 

[65swb45]

Assuming that this 72 is more or less bone stock, I would also be wondering what static timing and dwell is set at.

Then there is a possibility that somebody rebuilt your carb at some point and may have accidentally done something like replacing your slo jet with a different one that came with the kit without paying attention to whether it was the same size as stock.

 

[MandMAutomotive]

The timing could have been an issue.
Now that the timing is set do the mixture screws do any thing??
I would spend money to have a local shop try to dial it in before putting on a cat. You are not that far off, and idle failures can be the easiest to fix.

 

[xrock]

Break out the champagne!!! The 3rd time IS the charm~

HC
Loaded: 87 and idle 395 - Acceptable 400

Just barely squeaked in there! I had the idle set at 1200, adjusted the mixture and used a bit of alcohol.

Yea baby! Thanks to everyone for your help- Now I can get it registered and start figuring out the real problem.

Thanks again- You guys are awesome!