Ran the race car in a local race this weekend. Used a new holly clone carb( qwickfire) . went with standard jetting for this elevation but ran into a stumble at 2/3 throttle. Up to that point it was fine and at wide open throttle it was fine. Looked at plugs and burn looked normal. I suspect the accelerator pumps on this unit are a little small. Anyone else have an idea? Jerry
acceleration stumble
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Re: acceleration stumble
Ran the race car in a local race this weekend. Used a new holly clone carb( qwickfire) . went with standard jetting for this elevation but ran into a stumble at 2/3 throttle. Up to that point it was fine and at wide open throttle it was fine. Looked at plugs and burn looked normal. I suspect the accelerator pumps on this unit are a little small. Anyone else have an idea? JerryLast edited by Clem Z.; April 19, 2010, 10:46 AM.- Top
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Re: acceleration stumble
no leave in the primary but just going up 10 steps in jetting is not the correct way to get close to what you did have with a power valve in the secondary. the way i posted is the way to do it. it may come out 10 steps or it may come out 8 steps.- Top
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Re: acceleration stumble
Ran the race car in a local race this weekend. Used a new holly clone carb( qwickfire) . went with standard jetting for this elevation but ran into a stumble at 2/3 throttle. Up to that point it was fine and at wide open throttle it was fine. Looked at plugs and burn looked normal. I suspect the accelerator pumps on this unit are a little small. Anyone else have an idea? Jerry
I run a QFT750 on my 331. Came out of the box with 72/82 main jets, 6.5 in-hg primary PV, no secondary PV. It is a double squirter with no choke horn. The plugs are a little bit dark, and I haven't yet started to dial it in, but I anticipate going to 68/78 jets for starters. I am spoiled already because the slight rich mixture makes a cold engine start immediately and run without dying when cold (no choke). The thing pulls like a freight train with no stumbles or flat spots anywhere. Engine had slight detonation at cruise tip-in with the old 2818......but no more, with timing set for full power. 93 pump octane, no additives necessary.Last edited by Joe C.; April 19, 2010, 03:29 PM.- Top
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Re: acceleration stumble
Jerry,
From reading your post I assume the carburetor did not come with a secondary power valve.
When the secondary butterflys are opened in the last third of throttle opening, could you be running out of acellerator pump shot. Nozzle size two big, pump cam duration not long enough. Sounds like a gulp of air with nothing to smooth change over to secondary main circuit.- Top
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Re: acceleration stumble
If it is set properly and you still do not get enough fuel, you can install the "Reo" pump body to get more fuel. It is quite a bit larger than the stockDick Whittington- Top
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