Hey all, working on a friends 79 Trans-Am 4 speed with a 400hp butt dynoed Pontiac 400. Has a BG 750 mechanical double pumper. Runs pig, eyewatering rich. He just bought a Holley tuning kit and we are off. His vacuum advance was not even connected and he was beaming as it ripped the tires off in first and second for the first time in over a year. He needs tuning help, but this board has been a wealth of knowledge to me, so what do all of you know about tuning Holleys? Any special tips or tricks? (Besides jetting, that I can handle) I do need power valve recommendations though. Pulls 13" of vacuum. Revs to 5500, Edelbrock RPM Air Gap Intake. 6X heads
when you have it apart again , if needed , pay close attention to the metering block and body passage ways . not sure when your carb was produced but for awhile they had a QC problem with not getting all the metal chips and shavings etc out after machining and before assembly . i picked up a basic BG demon 600 carb from a guy that said it was just terrible and no customer service help from BG . when I got it apart there was some metal junk in there . a little internet search time is when I saw the comments about the QC thing . sold it after rebuild . ok as far as I know .
A wideband O2 sensor. https://www.racingjunk.com/news/201...right-power-valve-for-your-holley-carburetor/
If his car is a real W72 car, it’ll love the original qjet after a rebuild. I hope he still has the carb for it; they’re kinda valuable. (Sorry, I’m no help with a Holley). Patrick
When you buy a lot make sure it is the one for the carb as hollers used several block gaskets that were very close but different. These could plug or open the wrong passages.......just comparing the orginal gaskets is a good start, assuming they haven't ever been replaced with the wrong ones. Clean all passages every well, just a little dirt in an air bleed passage can cause issues......I like to spray cleaner through then air both directions
I was thinking the same thing! My son has a Silver Anniversary 79 TA 400-4 speed all original stuff still under the hood. I have another Pontiac project in the works for someone and am looking for a good Pontiac carb. Sorry John no help with the BG. But if the original Qjet is available and is any good and not spoken for..
