Recently installed a rb header with the “Y” pipe collecter (‘79 12a). Made all the necessary block off plates to spec and installed them. When I started the car up it ran ok until the choke pulled in and the engine died completely. Never had this problem before. It will hold rpms and smoothly. But once off the gas it hardly hunts or stutters before shutting off. Do I need to adjust carb for the new headers? Speed? A/f mixture? Floats?

 

You may need to adjust the mixture to make it richer at idle but that should be it. The headers will make it leaner than the old exhaust for sure.

 

Also make sure your block off plates are fully tightened down and all have gaskets. Sounds dumb but when I did mine the ACV plate on the intake wasn't tight enough and allowed an air leak, leaning it out. The bolts felt plenty tight, but something had bound up the threads. Took it off and re-applied fixed it.

 

I was thinking along these same lines, check for a vacuum leak somewhere in the system that doesn't allow your idle to lower to the same RPM as it did before the work.

 

Thanks a bunch! I’ll do a full nut and bolt check on the things I’ve changed

 

Please keep us posted on what you find and if/how you resolved the issues!

Stu A
80GS
AZ

 

Did the car run fine before the header install? Have you put a wideband on it?

 

car ran great for months before the header install. All stock components besides electronic ignition and headers

 

Have you tried to raise the idle to see if that helps at all?

 

UPDATE: did a full nut and bolt check on everything I’ve changed. Then dove into the idle speed and mixture. After some trial and error she’s steady at 760 rpm. Can go from full throttle to lift and catches itself perfectly. Might I add the headers are amazing. Sounds great looks great and the throttle response has definitely improved. THANK YOU for all the advice

 

Good to hear! Post up some pics of your car.