I just put a very slightly used 850 Demon on a mild 396 BBC.
Basic engine run down is...
Edelbrock RPM air gap, HEI dist., closed chamber oval port heads no porting or polishing, hyd cam with a 900 RPM idle speed, forged TRW pistons with small pop ups, Bassett headers. FYI, fuel level is 1/2 way up the sight glass on primarys and secondarys. I set total mechanical advance at 34 degrees on 91 octane pump gas. 4 corner idle screws are set 1 1/2 turns out.
The problem is, when reving up the engine in neutral (driveway) the accelerator pump shot is strong for the first 1/2 second and then peters out.
I think it needs a longer duration shot.
When I first blip (heavy into the primarys but not secondaries) the throttle, for that first 1/2 second, it's rich.
Should I reduce the shooter size to get a longer shot or play with the acclerator pump cam???
Might also be the power valve not opening? If I crack open the throttle and hold it there, the engine will rev for a split second and then actually die and have to restart the engine.
Never messed with a Demon carb before. Can someone give me a little guidance with this????
Be good, Jim