dartman59
Well-Known Member
Good afternoon fellow A-Body fans,
I'm having a devil of a time dialing in my new Holley Street Avenger 4160 770 cfm carb. It's on a '71 Dart; 408 (360 stroker, LA), 0.480", 274 deg, hyd flat tap, headers, 3" X-pipes, O2 in each collector; 4 speed, 3.55 gears. It pulls 17.0" vac at idle (900 rpm) and cruises at 21.5". PV is an 8.5. My A/F at idle is about 12.0. Ive been trying to lean out the cruise curcuit, but I've already jetted down to the lowest jets I have (64s--it came with 72s) and I'm still at about 13.5 When cruising on the level highway at 3,000 rpm. In that scenario, when I give it mild acceleration the AF goes lean (15.5-16.5) and stays there until the car reaches the higher speed, but it drops to 11.5-12.0 if I fully open the throttle so that the secondaries open. Cruising around town, rowing through the gears, I'm at AF of 11.5-12.0. Sitting still in neutral, here are my AFs:
RPM. A/F
900. 12.0
1200. 12.0
1500. 12.0
1800. 11.8
2200. 12.0
2500. 12.2
2800. 12.3
3000. 12.5
Why so rich? When I first bolted it on, and it had the 72 main jets, it would hwy cruise at about 11.8-12.0.
My transfer slot is a perfect square and I tweak my idle with the secondary screw. My float level is right at the center of the sight glass, front and back.
Am I missing something simple? I have noticed that my fuel pressure is normally about 6.5 but sometimes when I check it the pressure is high--9.5ish. Why would it vary and could that explain things?? It's a new Holley mechanical fuel pump.
Thanks for your thoughts and input.
I'm having a devil of a time dialing in my new Holley Street Avenger 4160 770 cfm carb. It's on a '71 Dart; 408 (360 stroker, LA), 0.480", 274 deg, hyd flat tap, headers, 3" X-pipes, O2 in each collector; 4 speed, 3.55 gears. It pulls 17.0" vac at idle (900 rpm) and cruises at 21.5". PV is an 8.5. My A/F at idle is about 12.0. Ive been trying to lean out the cruise curcuit, but I've already jetted down to the lowest jets I have (64s--it came with 72s) and I'm still at about 13.5 When cruising on the level highway at 3,000 rpm. In that scenario, when I give it mild acceleration the AF goes lean (15.5-16.5) and stays there until the car reaches the higher speed, but it drops to 11.5-12.0 if I fully open the throttle so that the secondaries open. Cruising around town, rowing through the gears, I'm at AF of 11.5-12.0. Sitting still in neutral, here are my AFs:
RPM. A/F
900. 12.0
1200. 12.0
1500. 12.0
1800. 11.8
2200. 12.0
2500. 12.2
2800. 12.3
3000. 12.5
Why so rich? When I first bolted it on, and it had the 72 main jets, it would hwy cruise at about 11.8-12.0.
My transfer slot is a perfect square and I tweak my idle with the secondary screw. My float level is right at the center of the sight glass, front and back.
Am I missing something simple? I have noticed that my fuel pressure is normally about 6.5 but sometimes when I check it the pressure is high--9.5ish. Why would it vary and could that explain things?? It's a new Holley mechanical fuel pump.
Thanks for your thoughts and input.