Help tuning my BB

[Novaddiction]

I need some help. I built my motor and had it dynoed now I am trying to learn to tune it.

Everything worked fine on the dyno. When I fired it up the other week first problem was a rocker hitting my baffle and valve cover, fixed. I have some valvetrain noise now on cylinder 8 so I'm going to recheck my valve lash.

The motor runs very rich at idle but seems to get better when it get's hot. It has a Demon 750 vacuum advance and I've heard of the same problem...some slight dieseling. I've tried adjusting the idle eaze/idle screws but not much luck. I've got my initial timing set to about 22*. It's idling fast and has eye burning exhaust.

I've read some post but other than that this will be the first time I've ever messed with dialing in a carb, maybe I need idle restrictors? Any pointers would be great. I just got a timing light and vacuum gauge but still need to get my tach hooked up.


402 .30
Comp hydraulic 292H .55 lift, 292 duration, 244 @ .050
10.3:1 CR
RPM air gap, port matched
Iron GM head, larger valves, port work
750 speed demon VS
MSD ignition with vacuum advance

[jason snyder]

SOOOOOO MANY variables!! But i will start with a few common problems.
1. make sure the float levels are correct.
2. hook up your vacuum gauge and see what you have @idle , install proper power valve.
3. make sure your transition slots are square (ask if your not sure about this).

give these a shot and get back to us.

[Novaddiction]

Vacuum at idle is around 15 now but jumps up when I hit the throttle.
I took the carb off the adjust the butterflies but they don't seem to respond well to me turning the screws?
Float levels are correct.

I've gotten the idle down now but it still runs rich. At WOT there is plenty of black smoke and at idle it has some burn you eye exhaust. I'm still trying to learn about the timing but it's set at 26 on the balancer at idle.

The noise was an exhuast leak that I found after resetting the valves.

[philly67]

just completed the very same engine, only diff.is a 3310 holly 750,,had same problem,,replaced power valve and went down 2 steps in jets,,set timing for 8 deg,with vacume line to dist. unhooked,,,now i can adjust idle screws and it wont choke you out,hope this helps

[jason snyder]

Vacuum at idle is around 15 now but jumps up when I hit the throttle.
I took the carb off the adjust the butterflies but they don't seem to respond well to me turning the screws?
Float levels are correct.

I've gotten the idle down now but it still runs rich. At WOT there is plenty of black smoke and at idle it has some burn you eye exhaust. I'm still trying to learn about the timing but it's set at 26 on the balancer at idle.

The noise was an exhuast leak that I found after resetting the valves.

IF YOU TURN YOUR IDLE MIXTURE SCREWS ALL THE WAY IN DOES IT DIE ?
caps,,,

[Novaddiction]

IF YOU TURN YOUR IDLE MIXTURE SCREWS ALL THE WAY IN DOES IT DIE ?
caps,,,


Nope, I think I need to jet it down. I'll get some on order and go from there.

Thanks.

[JamesC459]

if you close the mixture screws and the engine doesnt die,the PV is junk or you have an internal fuel leak causing your over rich condition