i just put a carb on my brand new 406. I switched from my current dfi efi setup cause I had many probs with it. I decided to go with the carb so i could enjoy the car this summer and mess with my dfi next year.

Here is the prob. I have a single plain intake with a holley 750 double pumper, part number 4779. The idle has to be up kinda high to stay idling. "1000rpm or so" Under part throttle the car goes down the road. now if i go wot at any rpm range it spitts sputters, pops and falls on its face bad. basicaly it goes knowhere. My friend and i have tried from 30-37 deg of timing and nothig it does the same thing every time. I have 73 jets in front and 81 in the rear. Everything else on the carb is stock, accelarator pump, pump cam etc. no matter what we do nothing works. We tried changing wires, plugs, dist, timing etc.

motor is a 406 11:1comp comp cam hr 194 242-248 dur@50 and 570-592 lift with 1.6 rockers. 110 ls.. heads are afr 210cc with 2.08 int valve and 1.6 exh fully forged bottom end.

Drew

 

Check for vaccuum leaks.

 

Sounds like you are starving for fuel. Put bigger squiters in it and if that does not work try changing the cams. How much fuel pressure are you running? I run mine at 6 psi to save the needle and seats. It may take a combination of squirters and cams to dial it in.

Good Luck !!!!

 

Thanx for the reply guys. After double checking everything again we found nothing. So a friend sugested that we recheck the valves and go through them again. SO we did that and wham!! she screams up the road like a runaway train...

Drew

 

So often, we think, "Gotta be the carb." About 25% of the time, it is.

I have a similar story. A few weeks ago, on the '57 I put in new retainers and valve seals, a GMPP crate HEI w/Accel coil & module, and a carb spacer. When I got it back together, it would fire & die, fire & die. I could keep it running if I held the RPMs up.

Since it won't idle, gotta be something with the carb, right? Took the spacer out, same thing. I'm supposed to be at the track, not trying to get it running. Gave up, took the Camaro instead.

Next day, went through the valve adjustment again, no difference. Took the Accel coil off, same thing. Finally, took the Accel module out - Bingo! No clue why it acted like that, but the stock module is doing fine.

Oh, put the spacer back in. Idles fine.