Ive got a new 750 speed demon on my 350 and have some questions about tuning it as i am new to carbs. Motor is a 350 with custom ground comp hyd roller (230/234 @ .050, .525/.525 110 lsa) with GMPP fast burn heads and performer RPM air gap intake. The carb is straight out of the box with 76-83 jets i believe. Im just trying to get an idea of where to start tuning with the jets....are these jets even in the ballpark, or should i start smaller? Ive heard these carbs will take holley jets, is that correct??? Any help would be appreciated.

 

Our motors are quite similar and I've still got the stock jets in my 750 Demon... I havent done any real tuning but it seems pretty close to right...

 

Welcome aboard.

Yes, you can use Holley jets.

First, get the floats and idle mixture set properly. Until you do that, the other things can't be done right.

Next, start with the jets the carb came with. Establish the cruise vacuum so you can pick the proper power valve (2 numbers below the lowest cruise vacuum you observe).

Then you can worry about jets.

 

I have a similar setup and a 650 Demon DP and it was perfect out of the box. I was a little bit lean on the dyno but that at see level and I live at 4300 ft.