I got my 65 k code on the road the other day with a rebuilt motor and all new components, it performed perfectly on the dyno and idles great but once it warms up going down the road it wants to miss under a load. we have checked everything and think maybe its the Holley 1850s 600 cfm manual choke, Ive been told by several other people one with a 66 gt350 that you'll never get it to run right unless you put the correct autolite 4100 that the hi po has characteristics that don't work well with the Holley?
holley 1850s
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- Official Post
Missing under a load is not usually carburetion unless the jetting is way off.
The carburetor is purely an air/fuel mixture device and does not know what brand it is. Yes, some brands do beter than others with cetain aspects of their job. Holleys are better at all out acceleration than the 4100 but the 4100 performs better on average driving. The 4100 has annular discharge boosters which better atomize the fuel, that are a hot rod modification on Holleys. The Hipo 289 has very mild characteristics compared to other OEM manufacturers high performance engines, as in smooth idling. I always run 4100 carburetors on my Hipo 289 Kars just because of originality. The 4100 works well for driving as long as you do not let the air bleeds get plugged in the boosters. A Holley works fine but for me, the 4100 is original, although it is far more expensive to acquire.
Your mileage may vary.
-Fred-
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You may want to pull the plugs and look for a cracked one.. you could also use a spray bottle and squirt the wires.. do it at night, you may see or hear some arcing.
Be sure you don’t have wires for 7 and 8 running next to each other.. try to separate them as best possible to prevent cross firing.
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Before changing anything carburetor related, I would check the ignition system. Three owners of Ford performance cars suddenly had faltering engines and all three found problems with ignition points and condensers; two of them had points gaps too small and one had screws holding points not much more than finger tight.
Otherwise problems with excessive wear in distributor bushings (plain bearings for the shaft), excessive gap between rotor tip and cap electrodes in some brands of caps and rotors, incorrect timing advance curve, cracked distributor caps, spark plug wire issues, and problem(s) the might prevent ignition timing advance have resulted in carburetors that were working well to be rebuilt needlessly or replaced.
One situation that can happen with manual chokes is installing the cable without some slack after the plate is closed. If the cable is just barely getting the choke plate closed engine vibration, road shocks, or engine movement during acceleration can partially close the choke. If the engine is running great and suddenly falters during acceleration, push on the choke knob to verify that the choke has not partially closed.
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