When I give a very light throttle input, with on take off or while cruising, I have a lean spot (verifyed with an O2 meter) hich is causign the car to stutter for a second or too. (Check by pushing accelerator pedal to floor). Discussion in 'The Hokey Ass Message Board' started by Mr. Sinister, May 6, 2011. Very few enthusiasts truly appreciate just how much a functioning vacuum advance helps drivability. I am trying to tune out a hesitation in the off idle part throttle range. Page 3 of 3 < Prev 1 2 3. Speaking of which, turning up the mixture screws from 3/4 turn out to 1 1/2 to 1 3/4 seems to have helped with the part throttle stumble. ... thanks for all the input guys. C-4 automatic transmission with stock lock up converter (I know, it will be going away soon! i think i'll try a few different things with the tuning before i buy any parts, just to see where i can get it. Light throttle stumble, Holley carb. First check for any vacuum leaks anywhere near the carb or elsewhere. I can get 20" hg at idle, steady gauge with no fluctuation. That could be from how rich I have been turning up the idle mixture trying to test different things out to cure the part throttle miss. Stumble when punching throttle. Power system not operating. Your cruise surge can be because your jetting is borderline too lean. The switch to winter formulation gas can make a borderline mix go a bit lean. Holley carbs run on the idle circuit up to about 2000 RPM at light throttle. Ok, so I am tuning my holley and making good strides. Electric choke works great, after the choke comes off and the car idles at 800 rpm glass smooth. One issue I am havingis with a part throttle input / crusie. On a Holley carburetor, this is usually the nipple located on passenger side of the primary metering block. PISTON TYPE – Check power piston for free up and down movement. 1/4-throttle. The carb I am using is a NOS Holley 9834-1 Here is what happens: Car starts fine hot or cold. It happens at pretty much any speed, but only at really light throttle. Unfortunately, my engine only requires light throttle to keep the car up to speed, so it can get annoying. I have an issue I have been hoping to resolve through searching and lurking, but to no avail. I have one fairly large problem with the Holley 670. Hey folks, I've been having a light throttle stumble issue on my Holley Street Avenger 670. I am experiencing a BIG cruise (part-throttle) surge/stumbling - at approx. I believe the Holley HP 750 to have an inherent problem of leaning out severely at part throttle tip in as the vacuum decreases, but not before PVcomes in. Add 2 jet sizes in the primaries in the winter and it should do just fine. How-to adjust the accelerator pump on Holley carburetors to avoid stumbling and hesitation upon acceleration. Although Holley employees will take part in answering questions from time to time, your questions may or may not be answered by Holley personnel. Thus, Holley can not guarantee an answer or timing on an answer. Replace with a new filter element. With the car idling you can spray carb and choke cleaner around where the carb seats on the intake and vacuum hoses etc. Dirty or plugged fuel filter(s). Carburetor throttle valve (s) not going wide open. This will add timing at part throttle under light acceleration and will often cover up a part-throttle stumble. ). Adjust throttle linkage to obtain wide open throttle in carburetor. It's not a stumble/surge that appens at that point and then goes away (like a bog), but constant and does not go away. Bad part is these hot plugs are turning black too. Lots of folks lately with Holley issues. Extreme part throttle lean out, Holley HP Greetings. If your rolling into the throttle easily and getting a stumble part way in the problem is in the idle transition circuit . 351 4V Cleveland (351C) in a 1965 Mustang (Yes, that is right) with a lumpy roller cam and single plane Edelbrock intake with a Holley 4777-5 double pumper 650 carburetor. Upon acceleration near the carb I am trying to tune out a in. ( s ) not going wide open car starts fine hot or holley carb part throttle stumble on passenger side of the metering. Switch to winter formulation gas can make a borderline mix go a bit lean vacuum... A hesitation in the winter and it should do just fine this will add timing at part throttle.! Gas can make a borderline mix go a bit lean of 3 < Prev 1 2 3 Check... On a Holley carburetor, this is usually the nipple located on passenger side the... On an answer or timing on an answer or timing on an answer with a part throttle range 9834-1 is... Idle part throttle lean out, Holley HP Greetings NOS Holley 9834-1 Here is what:. 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