Stumbles during launch

[Buicksandrail]

Hi,

I need some help. Just got the turbo back on. During launch in 1st gear the engine misses and stumbles badly. It is like someone pulled the plug. I have to let off the gas because it sounds like something is wrong. Once I get past 2500 RPM it accelerates like a rocket through all the gears with about 2-3 psi boost. The accelerator pump is working. I adjusted the secondary air vale to open faster but it didn't seem to help. I have not had this QJ carb on this engine before. The engine ran great before the turbo conversion with a 2bbl Holley.

Any suggestions out there?

Thanks as always,

Trent

 

[b4black]

When you launch, are smashing the pedal, or building boost and releasing the brake?

I woudln't look at the seconadaries yet. The bogging is probably happening before they even get a chance to open. Vacuum leaks can cause a bog and many vacuum leaks are within things (actuator), not just the hoses.

Why only 2-3 psi?

 

[Buicksandrail]

George,

I have a manual trans so I can't hold the brake. I just slip the clutch and let it go. I have a very simple vaccuum system. Most ports are plugged. My PECV is plumbed directly to the intake manifold using a check valve. It idles very smooth so I wouldn't suspect too big a vaccum leak and my vaccuum gauge is steady at about 14. I am running low boost because of my CR of 10:1. I blew a head gasket at 10 psi. Shouldn't my ESC keep the head gasket from blowing? Maybe is just had a bad gasket and the two aren't related? I can only get 91 octane in Cali.

It just pops real bad when I first get on it.

Thanks,

Trent

 

[b4black]

The ESC should retard timing to save the gaskets, but at 10:1 and 91 octane, it might not be able to pull enough timing out. What's your initial timing? Maybe you can recurve the distributor for less advance. Maybe a MSD BTM would be a good idea.

I would check the ESC controller. Maybe it's not functioning correctly. You can bypass it and see if the bog goes away. Peter's website has info on how to do this.

At only 2-3 psi, you don't need four barrels. I can pull 6 psi on just the primaries.

 

[Ttype83]

Check to make sure that the distributer & Rotor at seated right.