[texasimport]

Ok. . .the PO had just installed a new carb, manifold and distributor. He did not have it set up even close, mega rich stumbled etc.

So I have since changed the mains down three sizes from stock for the high altitude here .57 now .54. The floats were set so high, the secondaries were just dumping fuel. The acel pump was to tight. Idle mixture was way off, getting about 15 on the vac gage and that seems better now up from 12. I advanced timing a few deg and that helped but only a tiny bit.

Much less rich now but I am still getting some stumbling during med to hard aceleration. I think I only have two choices left. Maybe the vac secondary spring is to weak and I am getting to much fuel to soon or the power valve. I think it is stock PV is at 65 but with 15 vacum should I go with a 75?

Wadaya all think?

[texasimport]

Bump. . .

Hard to think that no one here knows how to fine tune a Holley.

[Totallymetal]

This has actually been talked about a lot. Here is a thread to check out. I also have a truck avenger 470 that I had to do a little tuning to get it right. Same as you 57 to 54 on the primary and secondary main jets, then adjust float level, then fuel/air to highest vacuum. I have had no problems. I bought mine new so the acc. pump and throttle blades were already adjusted from the factory. I also adjusted my fuel pressure to 5.5 psi using a Holley FPR.

Lots more information here, specific to our carbs.

[texasimport]

Originally Posted by Totallymetal

This has actually been talked about a lot. Here is a thread to check out. I also have a truck avenger 470 that I had to do a little tuning to get it right. Same as you 57 to 54 on the primary and secondary main jets, then adjust float level, then fuel/air to highest vacuum. I have had no problems. I bought mine new so the acc. pump and throttle blades were already adjusted from the factory. I also adjusted my fuel pressure to 5.5 psi using a Holley FPR.

Lots more information here, specific to our carbs.

Thanks for the reply . . . .I will check FP tonight and look into a FPR. The PO had just put a new fuel pump on as well so who knows on this one. What are the negative signs of running FP a bit higher than 5.5? Also went ahead and ordered the spring kit $10 and a couple power valves $9.

[Totallymetal]

Recommended fuel pressure is between 5-7 psi. You would probably be fine with a stock fuel pump, I just had a FPR handy, so I used it. It will reduce sudden bursts of fuel when traversing bumpy roads.