NAPA 1969 GS Carb Dashpot Number

Will do Thanks Larry!

 

A stock 69 should have 70 or possibly 71 jets, and 44B or 43B. There are other things to consider, but that gives you a range. Your jetting is currently way off. Hopefully, the rest of the Quadrajet wasn't recalibrated too. If the jets and rods were all that was done, that can be fixed.

 

Right Larry, I was giving a range for today's fuel depending on engine set up and elevation. Not 76's for sure.

 

This information comes from Guide to Buick Gran Sports: The Facts and Figures Book by Steven L. Dove with Dr. Jeffrey T. Moss

1969 Rochester 4MV Carburetor Specification chart for 400 Cu. In. engine auto. transmission: GM Factory Specifications

Carburetor Number: 7029242

Primary metering jet: .070

Primary metering rod: .045

Metering Rod Secondary: AY

Float Level: 3/8"

 

ttt

Please don't laugh I haven't got this all figured out.

 

If the dashpot doesn't work, or is missing, yes, that's a good start. Preventing a sudden throttle close helps keep hydrocarbons out of the exhaust stream.

I had a Chevelle with massive exhaust backfiring on closed throttle. AIR pump diverter valve was faulty. Pushed injected air into the exhaust manifolds when manifold vacuum was high (throttle shut) Got so bad that the mufflers exploded.

While your carb has been tampered with, be aware that often "smells gassy at idle" is a matter of misfire (including LEAN misfire) where the entire cylinder-load of fuel goes out the tailpipe un-burned.

 

Backfire seems to be gone now with the recurved distributor and I'm hoping some of the carb richness may disappear when I move to the Stage 1 or Poston 113 cam and Offenhouser intake manifold.

 

Nothing yet on the jetting. Just runs a little rich which is better than lean wrt hot climates. Next step is to replace the exhaust system to eliminate the double wall closing up my drivers side exhaust side.

 

So you're pushing an enormous amount of exhaust through the intake manifold exhaust crossover, overheating the carb?

 

Very likely I guess.

 

Exhaust done. Carb next. Still way too much gass.

 

Is my gas pig carb ready for E85? I just found it nearly for more than 30% less than the 91 I can get. No 93 octane here. Any thoughts would be great. Before I go deal with the carb guy.