63RancheroGuy
Active member
Hi folks,
My '63 Ranchero has a stock 170, 1100 L-O-M carb, 4-speed manual trans, pertronix I ignition, new plugs gapped to 0.040", new rotor, new cap, recently replaced accelerator pump diaphragm. I live at about 200 ft elevation if thats pertinent.
The problem is after she warms up, I can open the choke all the way (push the knob all the way in) and it will idle fine at about 850 rpms (is this too high?). But from a stoplight, it will accelerate but roughly - almost stuttery like its missing. However, if I begin to close the choke just a little, say I pull the handle about 1/8-1/4 of the way out which just barely moves the butterfly, it kicks the idle up a tad (to about 1200ish), and then there is smooth acceleration, no sign of trouble. If I push the choke in just a bit, the idle speed decreases a little and the roughness starts to appear but not as bad. The roughness only appears on acceleration, if I just pick a speed and cruise along - no trouble.
The pertonix ignition is fairly new, but the roughness problem was present before the new ignition. After the ignition, the engine does run smoother than before but the roughness on going fromt stand-still up to cruising speed feels about the same.
I don't know if its related but another issue is if I'm cruising along with the choke all the way open, and I take my foot off the gas to decelerate, the exhaust sounds like a motorcycle: "Brap-brap-brap-brap" for lack of a better explanation. But, with the choke-knob in the slightly pulled out position, it makes no such noise on deceleration.
I'm actually fine with driving with the choke out just a tad, but I figure I shouldn't NEED to, y'know?
Any thoughts on diagnoses or diagnosing this problem?
Thanks in advance.
Adam
My '63 Ranchero has a stock 170, 1100 L-O-M carb, 4-speed manual trans, pertronix I ignition, new plugs gapped to 0.040", new rotor, new cap, recently replaced accelerator pump diaphragm. I live at about 200 ft elevation if thats pertinent.
The problem is after she warms up, I can open the choke all the way (push the knob all the way in) and it will idle fine at about 850 rpms (is this too high?). But from a stoplight, it will accelerate but roughly - almost stuttery like its missing. However, if I begin to close the choke just a little, say I pull the handle about 1/8-1/4 of the way out which just barely moves the butterfly, it kicks the idle up a tad (to about 1200ish), and then there is smooth acceleration, no sign of trouble. If I push the choke in just a bit, the idle speed decreases a little and the roughness starts to appear but not as bad. The roughness only appears on acceleration, if I just pick a speed and cruise along - no trouble.
The pertonix ignition is fairly new, but the roughness problem was present before the new ignition. After the ignition, the engine does run smoother than before but the roughness on going fromt stand-still up to cruising speed feels about the same.
I don't know if its related but another issue is if I'm cruising along with the choke all the way open, and I take my foot off the gas to decelerate, the exhaust sounds like a motorcycle: "Brap-brap-brap-brap" for lack of a better explanation. But, with the choke-knob in the slightly pulled out position, it makes no such noise on deceleration.
I'm actually fine with driving with the choke out just a tad, but I figure I shouldn't NEED to, y'know?
Any thoughts on diagnoses or diagnosing this problem?
Thanks in advance.
Adam