Yeah... moving the reference line from the manifold to the carb hat was a night and day difference. And Percent is correct, you want the reference seeing the same pressure as the float bowl, so that fuel pressure rises consistently with boost. Anywhere else, according to the turbo mustang guys, and you have to try to account for the pressure drop inside the carb or before/after the intercooler. As for my carb, it's pretty much the same as a Weber DCOE in operation (in fact I replaced a DCOE with this carb) but has some slight improvements in externally adjustable floats and acellerator pump.

Another note regarding the issue. I bumped the pressure up on the regulator to around 6 psi base and the car seems to be much happier. Tip in use to have a stumble, and it's gone. Idle AFR's used to bounce between 11.9 and 13.1, now they're a rock solid 12.6. Carb doesn't lean out as quickly either. Raised the pressure a little more to around 8 psi base and it started to flood out at idle, so 6 seems to be the sweet spot, but the flooding could have been caused by the erratic pressure, because it was bouncing between 8 and 11 psi.

Just so no one panics... I'm not boosting the car until the Aeromotive regulator gets here. Should have it tomorrow and installed this weekend... I'll keep everyone posted.

 

Well, Summit came through with super fast shipping again. So I installed the Aeromotive during my lunch break and pressure is rock solid!!!

Car is still wanting to go lean as boost comes on, but I'm pretty confident it's just jetting. I haven;t been messing with jetting until i could get this fuel delivery issue sorted. Guess I know what I'm doing this weekend.

FWIW, I'd go with the Aeromotive over the 4309 any day. The Aeromotive is EXTREMELY well built and feels VERY solid, it makes the 4309 look like a piece of junk. For the extra $40 the 13301 is well worth it.

 

I almost got the Aeromotive rather than the Mallory. My Mallory has worked well for me, but you're right that it seems cheaply built.

 

A direct quote from the turbo mustang guys.... "Mallory should stick to ignitions...."

 

You've about got me sold on that thing.

Sounds like the air is getting there before the extra fuel from the regulator. Have you jetted the accel pump?

 

Acell pump jets have been tuned.... err... removed. Not running any AP jets... gets the biggest shot possible.

I think I found the issue. I have a broken engine to intake manifold bolt that I just noticed. Thank god for premix. I noticed an oily, sticky residue on the rear rotor intake runner and running down the rear iron. So I'm thinking that boost/fuel is leaking out through the manifold flange.

Just ordered some Grade 8 studs and Nyloc nuts from McMaster-Carr ( i love that place), and going to replace all of the manifold to engine bolts with studs. Should make installation much easier and won't have to worry about breaking another bolt.

 

Wow... so how long does the shot last without a jet?

Yeah, that can't be good. Let's hope that fixes the issue.

I just ordered one of those Aeromotive regulators for my own build. I've almost got everything I need to start putting it all together.

 

Does your carb have nitrofil foats in it. If it doesnt that could be the cause of your erratic fule pressure,

 

It's an OER, so yes, it does.