Speed Demon 750 Nasy Hesitation

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Jo Diesel

Jo Diesel

My other car is a Dodge
Joined
Nov 24, 2010
Messages
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Location
St. Johns MI
My engine is as in my sig and I can't get this hesitation to go away. It is under moderate acceleration just after the acc pump runs out. Runs great at cruise and full power or as soon as you get into the secondaries. I have changed Power Valve 4 times and even jetted a little richer but still SUCKS!!! Timing is 12 initial, 36 total at 3500 pm with vacuum advance hooked up to manifold vacuum. Jets are 74, 86 50cc accelator pumps, green cam, #32 anualler squirters on a mech secondary carb. Right now I have a 650 vac secondary Holley with 72, 82 jets and runs perfect, just lacks the power of the 750.
 
Have you tried running your vacuum advance on the ported side of the carb?
 
......what is happening is that u loose vaccum when u open the throttle causing a big reduction in ur timing....u cant set them up like a chivvy, they just dont like it.....disconnect ur vacc adv and plug the carb port.....bump ur initial timing to 14-20.....check ur total timing.....get ur timing sorted out 1st, then work on the carby....kim......
 
I tried both with vac advance and makes it worse. Car runs perfect with Holley so I do not think it is timing. Cam is an ISKY VOODOO 276 duration, 476 lift.
 
Jo Diesel said:
I tried both with vac advance and makes it worse. Car runs perfect with Holley so I do not think it is timing. Cam is an ISKY VOODOO 276 duration, 476 lift.
Click to expand...

have you find out what the problem was with the carb? I have a Barry grant sports claw that does the exact same thing as yours.

//Daniel
 
Initial timing is 12, with vac advanced hooked up to manifold vac at idle is 24, full advance is in at 2500 rpm is 36. I tried port vacuum and it killed my fuel economy. From 12 to 8 mpg. I have been tuning and rebuilding Holley's and Quadrajets for 30 years and have never had this problem. Tried BG's tech line and they have never replied.
Somewhere I read that other people have had this problem and I saw where somone did some drilling in the transfer circuits but I can not find it. THERE IS DEFENITLY SOMETHING WRONG WITH THIS CARB. :banghead::wack:probably why the person I got it from unloaded it.
 
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