I beg of anyone that can help me!As anyone knows I have been tuning my Speed Demon for the last few months.I have the carb so close (with the help of many here) and it runs so damn good.One problem..a nice dead spot when I rev the car at idle.I have cured all other problems from start to finish.Driving the car runs mint.This problem I am having now is just me being **** about my car running 100%.There is a small dead spot when I rev the car say sitting at a light.Taking off..mashing it from dead stop...no problem..just the red light rev.Will lean primary jetting cause this?I have raised/lowered float levels,installed correct PV,set correct idle mixture/transfer slot settings,advance curve springs,base timing.etc.ANY IDEAS..greatly appreciated.Oh yeah..I have tried every pump cam in the kit..most at both settings (1 or 2) to no avail..what cam is the most aggresive??To me it looks to be either the black or green cam...but yet the white cam gives me the most aggresive shot..and get this.I had to install it backwards..actually flipped over to get these results and the number 2 holes lined up to the number 1 hole.That is with a 40 squirter (from 31 stock..big increase!) also which seems way too large to me.Yes I am running the hollow screws for it.Please help..I am ready to try the 50cc accelerator pump kit next..but that may be awhile being as my daughter will be here soon...expecting dad!

 

I assume you're talking about slow application of throttle with no load on the engine that produces this dead space. Would the same thing happen if you were coasting (in gear) at idle and slowly add throttle?

What power valve did you choose, and how did you determine that it is the "correct PV"?

 

Exactly..cruising in gear at very very light throttle and just barely get into it and BAM..small dead spot,not really bad at all but I am **** with how my car runs and drives.But yet mash it from cruising and away we go..no dead spot,sputter,anything.And of course,the red light rev that gives me the same dead spot,it always has that dead spot at idle when revved.I have a 9.5" PV in it now as per Demons instructions to go with one about 2" below my hot idle vacuum which is 11.5"-12" in neutral (stick car) with a healthy street motor.The PV did wonders for what used to be a huge hole in throttle delivery,but I still have this little spot,which pisses me off so bad cause nothing seems to get rid of it.Only other thing I can think of to do is drill the throttle blades,which I am reluctant to do being as there is no way to go back after that.

 

Hmmm, that's a higher PV than I would have expected. Can't really go higher w/o it being open all the time.

Have you checked cruise vacuum at say 40 mph & 60 mph? If it is above 13, say, you could probably go up one more PV. But, that's stretching it considering your idle vacuum, so drilling the throttle blades may be the only option.

 

Shoot some propane down the carb while winging the throttle
as you would while experienceing the dead spot.
If the extra fuel(propane) cures the problem then you need more shooter. If it is still there, it's an ignition problem.
The extra propane will enrichen the mixture if it is a lack of fuel
problem.

Could be a vacuum leak.

 

I will try that propane trick you talk of F-BIRD'88..sounds like an idea!Thanks guys..a few more areas to check at before I give up and deal with it.