Carburator Question

[Blue68Coupe]

So I replaced my 650 Holley with a 525 Street Demon. Now the car idles like never before but has one heck of a hesitation off idle. Demon said replace the power valve with a 10.5 but that did nothing. I tried a smaller accelerator nozzle since I had one laying around and it made it worse. The car feels like it takes off as long as the accelerator pump is shooting but there is too much time between it stopping and the normal circuit taking over. So I get a surge and then nothing and then it runs again. It does not do this at highway speeds but it does it all the time at low speed.

The car has about 12 vacuum at idle, 289 bored .030, aluminum heads, mild cam, roller rockers, headers, etc. My Holley never did that, I just couldn't get it to idle.

Any ideas on what to try next?

[Rev]

You might need a 50cc accelerator pump instead of the 30cc pump it comes with. I did have to put one in my 625 Road demon after I went to a little bigger cam. It sounds to me like you are running out of shot before the main jets and power valve kick in.,

Rev

[Phillyfanfrombirth]

Tuning Tips and Trouble Shooting

Here's a trouble shooting guide...

I'm not familiar with Demon carbs... I was going to suggest trying a different cam. I know I spent a couple weekends with my Holley 700 playing with different cam set ups...