I actually watched ENGINE MASTER last night, the blow-thru Ford 363 with the test of the DEMON 650 BLOW-THRU vs Holley Super Snper Stealth 1250, and Brule even mentioned that they can never get the fuel curve right on the EFI with a dual plane.....

 

Honestly I know nothing about EFI, I only know carburetors, you might want to put your question to cutlas EFI. The customer watched his 455 run on the dyno Tuesday, and was very happy and loaded it up and headed back to Colorado. As the engine crested his tailgate, I had a few thoughts, first was utter relief of seeing it leaving, then the thought of what it takes to do one of these builds correctly, which is a difficult build to say the least, and we can talk about that if any of you are interested, and if not I'd only say, you better have a good machine shop that cares, with some serious crankshaft grinding capabilities, and be able to check and modify clearances, and I would throw in some fabrication skills as well.....................

 

Mark, same shop that does Dale's (Canadian olds) did my short originally, actually the whole stock W30.
This go round, same shop will inspect the short, but another shop is doing the assembly, head, intake and custom solid roller cam and related stuff.

Thus shop built my other BBc stuff, like the 800+ Hp 475 with GM heads and intake, or the 498 1270Hp Big Chief motor to name a few. The shop has done a bunch of other stuff and is usually quite well versed in other engine design too.

So hopefully it will all work out. But I WILL be reaching out for you again for some insight too, as we haven't spoken in a few years now.

 

You should be fine then.

 

There will be an imbalance on every cylinder, and side to side with a dual plane. I see it on my EGT’s on every dual plane equipped engine I do.
And NO TBI unit atomizes the fuel as well as a carb does, so the distribution can actually get worse as the fuel drops out of suspension. But they typically won’t tell you that.
However, oddly enough, when you get them all pretty even, the power won’t change as much as you’d think. The main thing it effects is just having to tune to the worst cylinder.

 

unless it’s a dead stock style build using a dual plane…you need to blow out the plenum to the max you can get and add as much spacers as you can.

if you plan on going to the dyno, set it up with a left and right O2 bungs so you can find out which it likes best by switching back and forth..then stick with the side that gives the best fuel curve and power. use the same sensor so you know there isn’t any discrepancies between two different ones.

when opening up the plenum.. go as wide on all sides as you can, don’t be concerned about matching it to the 4150 dimensions..go as big as the casting allows