Thinking of switching to a road or race Demon 750 mech secondary. Anyone use these & how's the idle etc. The  Edlelbrock Performer 750 that I know have is great as far as idle and a very smooth acceleration, but I start running out of gas a 4000RPM + when I open the back barrels. I also have a older Holly Double pumper that was a bear to keep setup right, but when it was the engine would climb to the red line fast & smooth. My engine is a 454HO thats been modified somewhat & I run a TKO-600 with a 3.73 Posi HD Rear. Any input would be appreciated.

Alan

Well TBO, it sounds like the Edelbrock Secondaries are not opening.  Not a carb I know a lot about, but if you think a different 750 cfm carb is going to make it rev farther then the current one is wrong.  The CFM is the same, so the results will be the same.  I think your problem is in the tune up on the carb.  I would make sure the secondaries are opening and the fuel is there.

We have seen several cases on the dyno where a vacuum seondary spring was way to strong and the secondaries were not coming open, put in a lighter spring and instantly we would pick up 30 to 40 hp and the engine would run to redline.

thanks for the info I'll check out the secondaries I know I'm getting gas because the holly pulled good & I haven't changed anything in the fuel system since switching. Get alot better gas mileage with the edelbrock...probably cause I'm running on 2 barrels.

Alan