428 Carb Set up

[Mr.Fixit]

"I never made it to full throttle. It would drop to about 3.5 when I would put the throttle about half way down- rpm was around 2800 or 3000. If I rolled on the throttle, it would pull hard, but if I stepped on it, it would hesitate/miss for a while and eventually smooth out and pull hard. This was the same with the standard spring in the secondary or the small yellow spring. "

the hesitation of WOT is accell pump related. Try the green cam and a bigger squirter. The secondary spring will be of no effect for this problem. It also sounds like the PV isn't opening and adding the fuel enrichment for WOT if you have a "it would hesitate/miss for a while and eventually smooth out and pull hard" the accell pump will only cover up a small lean condition. Sometimes going up one jet size will take care of this kind of lean miss, when you can't get it all with the accell pump. Your eyes shouldn't be burning however.

[Chaplin]

I'll give that a try. How much bigger should I go on the squirter? It's a 31 right now, should I go to 34 or 35?

Thanks again guys.

[rdorman]

Oh! From reading your post I thought the miss/hesitation got worse when you went down on the jet size. Do play with the pump and go from there!
Rick

[Chaplin]

Come on Rick pay attention, keep up with the rest of the class I had the same problem the day before with the 72s and did not seem any worse with the 70s.

[Chaplin]

Here's an update. Switched the jets to 74s in the primaries, changed the discharge nozzle to a 35 and left the 3.5 pv.

Car ran much better and felt like it had more power. The stumbling around 1800-2000 is cured. Now you can put your foot to the floor in 4th at 1800 and it will pull smoothly.

There is one remaining problem, though. If you look at my last post, when cruising at 25-2800 and stepping on it, the motor would hesitate and miss and then pull hard. Changing the jets to 74s and increasing the discharge nozzle helped a lot, but the problem is still there, only now it happens (but not as badly as before) around 3000-3300 rpm.

I have not yet tried the green accelerator pump cam. What do you suggest for next steps?. Should I change the pump cam first, then try a larger discharge nozzle and then try 75 or 76 jets or just change the jets? Or alterntaively, should I leave everything the same and jump up to a 4.5 pv even though my idle vacuum is only around 5 or 5.5?

Chaplin
Master Carburetor Remover