Holley 4150 HELP needed fast......
 

Engine is a ZZ4, Edelbrock RPM Air Gap intake, Pro Systems 4150 carb, I had a real rich condition at idle when I first got the carb last summer and switched the idle air bleeds from 70's up to 78's to lean it out more at idle. Idle mixture screws are out about 3/4's of a turn at all for corners, and the idle transfer slot is set at .020 exposure.

So over the winter I changed from an MSD E-Curve distributor (could NOT dial that dang thing in to save my life) to an MSD 8360 with a Blaster coil (no MSD box). I also changed from a 4 hole 1/2" carb spacer to an open 1/2" spacer.

The only other change was on the fuel pump from 90° NPT fittings into and out of the fuel pump to Fragola Pro Flo 90° fittings.

So I set the base timing at 14° and attempt to fire up the car and it starts but it won't stay running. If you feather the throttle a lot it will struggle to hang in there around 1500-2000 rpm but eventually will die. Being that it sat for the last 4 months over the winter I didn't want to get too radical with it until I got some oil circulating.

SO.......where do I go from here?? :bang:

I am ultimately trying to get this dialed in by Friday for the Heidt's track event here in suburban Chicago. Sure glad I took vacations days on Thursday and Friday!!

Sure sounds like a vacuum leak.

Are you getting fuel? Possibly the filter? Check to see if any of the floats are stuck and check float levels.

Fresh gaskets on the new spacer?

How did you set the base timing?

3 changes - spacer, ignition, fuel fittings.......ignition would be my primary suspect, vacuum leak from spacer second.

Is the ignition properly grounded by MSD standards?

Yes fuel is flowing well from the squirters, float levels are good!

Fresh gaskets?....NO...I did reuse the old gaskets. Stopping at the local Speed Shop on the way home tonight for fresh gaskets.

I replacied another MSD distributer which had the exact same electrical hookups, so I would eliminate that possiblilty as I had no problems in the past.

These statements make me wonder about ground. "Couldn't dial it and replaced it"..... No problems?

Mine was grounded to the firewall with a grounding washer and it wasn't good enough, even with the firewall/subframe ground strap in place. Grounded to intake manifold with a good engine grounds and erratic problems neutralized.

BUT, the old MSD distributor worked fine at the time the car was shut off the last time it was run. The two distributors use identical electrical connections and they utilize exact same WeatherPak connector - Plug n Play.

When I installed the first distributor I used a firewall ground - FAIL, switched to an engine ground and VAROOM. So I know the ground it good.

I picked up some new carb gaskets to eliminate the the vacuum leak possibility.

The car sat for several months with fuel in the carb? This ethanol junk we spend too much money on, is quick to goo up stuff. I have to run everything I have out of fuel if I'm storing it for very long. Just a thought....

Not picking on you just observations. My MSD wouldn't function with the same ground the previous Mallory Unilite used..........much more sensitive electronics.

It's a slow methodical one step and test process...........

When I pull the carb off for the winter, it gets drained of all fuel. Last weekend I blew out all of the air and fuel passages in the main body and metering blocks, so all should be good there.

My friend I know you're not picking on me, I know the road that you have traveled, so I respect your ideas as real world experience!! I'll check it out!! :thumbsup:

THANKS for all of your input!!

:hairpullout: :thumbsup: