I recently bought an 86 IROC that was converted to a carb setup. I dont know too much about carbs so ill try to explain as best I can. The carb is a 650 cfm holly with vacuum secondarys and im having a few problems with it. The first problem is that when the engine gets warmed up the idle climbs up to around 1500 RPM. The second problem is that whenver i bring it to wide open throttle the engine bogs down like its getting way too much fuel. If i bring it to wide open thottle from 0mph somtimes the engine will stall. Is there an adjustment I can make to contol the opening of the secondarys? If anyone knows any web sites with good info on tuning holly carbs please let me know.

 

By the idle screw, if you pull the throttle to WOP you can see how it catches a screw and opens the secondaries. My car wouldnt idle lower than 1500 RPMS because i had a big vacuum leak because i needed new gaskets for the spacer.

 

High idle is usually an indication of a vacuum leak or the choke isn't opening all the way (or the choke linkage or high idle screw is not adjusted correctly).

Stalls when you nail it? Usuaully the accelerator pump is having problems of some sort. Worn out diaphragm, check ball/flapper or the linkage is mis-adjusted or bent.

I notice you live in Philly. I'm in between Philly and Wilmington. I've helped a LOT of guys with carb problems. Carbs are my strong suit. If you want you could drop me an email and we could get together one weekend (or after work) and I could have a look at it for you. This problem shouldn't be too tough to diagnose/fix.

 

As of now, the carb doesnt have a choke so Im probably looking at a vacuum leak then. But the idle is only high after the engine has been warmed up. Any good tips on finding a vacuum leak? With the air cleaner off I can see the accelerator pumps squirting fuel so they seem to be working correctly. The engine only stumbles under hard accereration, if I gradually bring it to wot it starts to pull pretty good. I pulled a few of my plugs today and they were black as hell and my gas mileage is horrible, so Im sure Im getting too much fuel Im just not sure how to adjust it. I live a few miles west of Philly in Drexel Hill so maybe we can meet up if I cant figure this out within the next few days. Thanks for the help!