Hesitation / bog with new combo

[68 RR]

Still working the bugs out of my new 383. After sending the "stock" style Mopar Electronic ignition back to Jegs and ordering a Pertronix Flamethrower Distributor with ignitor III it is running again. It seems to run great except for a flat spot right off idle. If I really stab the throttle fast it will actually die. I'm not sure where to start because I have never really had it running perfect since I built the motor. Any suggestions...Carb? Ignition? Timing? I have tried setting the initial anywhere between 12-16 and it made no difference. I don't know what the full advance is going to. I put the lightest springs in the vacuum advance tonight and I will see if it makes any difference tomorrow. :confused:

 

[Redpolara]

It sounds alot like a carb issue,have you checked the pump squirters?.
If the accelerator pump isn't working efficently,the carb won't have any progression between the idle circut and the main circut....hence the flat spot.

Just another thought.....carbs like "air speed".....they'll flat spot if they don't have enough.......so,maybe the 830 Holley just doesn't have enough of it on the bottom end with your current combo.

If all else fails,try a smaller carb.

 

[Histoy]

I agree with Redpolara, that it could be a carb issue. Did you change the carb when you built the engine?