Stumble/Hesitation on light throttle

[71Duster]

On my 750 Mighty Demon annular I have a slight stumble/hesitiation @ 1900 to 2000rpm while cruiseing only with a slight tip into the throttle.

It had factory 31 shooters front and back, I changed the front to a 35 and it seemed to get a bit better. Should I keep going bigger or is there another problem?

The air fuel ratios have been checked while driveign and are all good so I'm not worried about jetting. Vacuum in gear at idle it pulls are 11 - 12" so I have also left the factory 6.5 power valve in it.

 

[JoeDust451]

On my 750 Mighty Demon annular I have a slight stumble/hesitiation @ 1900 to 2000rpm while cruiseing only with a slight tip into the throttle.

It had factory 31 shooters front and back, I changed the front to a 35 and it seemed to get a bit better. Should I keep going bigger or is there another problem?

The air fuel ratios have been checked while driveign and are all good so I'm not worried about jetting. Vacuum in gear at idle it pulls are 11 - 12" so I have also left the factory 6.5 power valve in it.

Have you checked the AFR in the idle/cruise mode, you might have it a bit lean, this will cause a problem like you discibed, Any time i've had this issue on my holleys, it was useally a lean idle curcuit/cruise, going to a larger squirter "helped", but then once i fixed (richened up) the transition the squirter was then too much, i ended up going back to stock size & all was great.

 

[71Duster]

A/F was 12.73 to 12.85 at wide open throttle and 13.56 to 13.78 at cruise with a good reading on the plugs.

Was told I could drop two jet sizes up front provided it doesn't ping. How do you richen up the transition?

 

[JoeDust451]

A/F was 12.73 to 12.85 at wide open throttle and 13.56 to 13.78 at cruise with a good reading on the plugs.

Was told I could drop two jet sizes up front provided it doesn't ping. How do you richen up the transition?

I wouldn't start messing with the jets, especially on the drop, your already exsperiencing a lean transition, You can tailer in the curcuit buy either "decreasing" the IABs (idle air bleeds), "increasing" the PVCRs (PV channel restrictors), have you tried bringing the Mix screws out more?

Being a Mighty Demon, it should have screw-in bleeds, maybe even in the metering blocks, so it should be easy, Also, make sure both F&R throttle blades & mix screws are even, & that the float levels are right, you can run the level about 60% up on the glass window, just a tad over 1/2 way up, you can get away with less AFR then 13.60ish, I would try 13.0-13.20. Double check the pump arm adjustments also, make sure it shoots a steady stream of fuel & it starts as soon as you touch the throttle.