OK guys, I know this has been beat to death, and I've read and read and read.

Its a known fact that a single plane exposes the cylinders to more airflow vs a dual plane.

It would stand to reason that with a single plane, with the added exposure to total airflow, additional fuel is included with the additional airflow.

I originally started out with the Edel TB manifold. This worked well up to 4700 RPM, where it flattened out.

Currently, I am using the RPM Air Gap, and the engine pulls stronger throughout the RPM range, plus it will pull to the cam's RPM rating of 5200.

But, by plug cuts I am way lean. So lean, I have a miss that starts at 4500 RPM.

I have yet to start the custom tuning and was wondering if I might as well install the single plane I have prior to tuning.

Plus, my fuel pump won't maintain fuel pressure above 26. I have the Holley 12-903 pump that will soon be installed. From what I'm seeing, I may need in excess of 30 psi.

I can't remember the original application for the fuel pump that I have now, but it is for a supercharged Buick (NO, not a GN).

Anyway, do you think the inability to maintain fuel pressure is the regulator or the pump? The reg is the GM vac ref FPR that has been made adjustable. I know GM also has a TBI FPR that is rated at ~28 lbs; I was wondering if I should just use the spring from that in my current reg.

BTW, this is a 454 TBI pickup with a modified TB with 2.2 inch bores.

Thanks

 

No, definately get the ability to tune before you go tossing manifolds around. A lean condition will just get worse with a single plane. The only way more fuel is introduced is if you program it in the chip. Air on the other hand will come in if you let it regardless of the fuel.

As for your fuel pressure... are you talking about fuel pressure WOT? run a gauge and if you see the pressure dropping on a WOT run at high rpm then you have a problem.


I highly suggest a wide band oxygen sensor setup

 

Ok, that takes care of the manifold swap for now.

I wasn't clear about the fuel pressure problem. I can adjust the fuel pressure to 28. If I disconnect the vac source to the reg, the fuel pressure drops to 26 even while increasing engine speed sitting still. This also happens while driving at part throttle and WOT.

WB O2 is definitely in my plans.

Thanks

Bill

 

If you have the fuel pump then I'd put it in just for piece of mind. If not, I know they were having a $99 group purchase on the walbro 255's on camaroz28.com, that's a good price, saves about $10. I agree with Pablo on the tuning, the RPM pulls solid with my small lt1 cam to ~5500.

 

Yes, I already have the pump.

I've ordered a plastic replacement fuel tank also. This will save me ~15 lbs over the stock steel tank, plus eliminate any corrosion issues.

Gonna install the above while its in the air getting the 4.10's.

I know 15 lbs isn't much, but I need all the help I can get trying to get 4500 lbs moving!