Dominator on Indy motor fouling #7

Hey guys. I run a 500" Indy motor in a A body. 440-1 heads, Indy 440-2 intake. With my 4150 series carb It's a steady 5.95-6.05 @112-ish car depending on weather & track. Typically a 1.37 or lower 60'

I wanted to go to a Dominator. So I borrowed an older 7320 Holley and mounted it with a Wilson Manifolds open adapter 1.5" tall. When I fired it early this past spring it fouled #7 plug almost immediately. So I put my 4150 back on and it was good to go. Last weekend was running 6.01 on the 4150.

In the meantime I ordered a new custom dominator from a well known builder. Not saying who right now because I don't need all those carb builder loyalties to come out.

So this past week I put on the brand new dominator. Again with the 1.5" adapter. And guess what? #7 fouling very quickly. Plug doesn't look all that bad but I'm checking them at idle with an IR temp gun and 7 is at 200° while the others are above 500°. Here's a temp check at idle aiming the beam right at the tube about an inch or two from the port.
Exhaust temp check video

I'm running Autolite AR3910's, MSD box, with 35° timing

Any thoughts or guidance on correcting the issue? I'm open to suggestions.

-Thanks

Back cylinders typically run richer and need less het.
How does your #8 , #5, and #6 look?

Ask the carb builder . Usually that’s why you go to these guys , service after the sale .

Two different carbs with the same results leads me to believe the manifold with the adapter is causing your problems
Is your intake a early or late 440-2? The early ones have individual raise bumps on the intake runners for injector use, the later ones have one oval boss that sits across two intake ports down low next to the heads. I don't remember now which one has the intake port wall divider sticking out into the plenum under the carb, the other one doesn't have that
IHTHs

I’d see if one of your friends has a different style of 4500/4150 adapter you could try.

I’d also take the carb off after letting the motor idle for a bit and see if the plenum floor is kinda wet.

n2Omonster, yes, you are right. Shot him an email & videos today. Following up with a call tomorrow..

Cab_Burg & fast68, I Agee it feels very spacer/manifold related. The manifold I have has the oval injector boss castings across both adjoining ports.

Sammy, I did not pull 5,6,8 but I did pull 8,1, 2 which seemed fine. But you raise a good point on 5 & 6.

-MHZ

I have a simular issue. My #7 runs darker than the rest. Cab suggested running one range hotter plug in that hole. Never did try that yet. 511 using the Indy 400-3 with a Thumper 1100. After removing the clover leaf and porting the plenum and runner transition the plug doesnt run near as dark as it used to. It has never fouled. My 400-3 is a later version and does not have the port divider extentions.

pull out 5 jet sizes out of the secondary drivers side and see if the problem goes away. or go 4 sizes larger on the high speed air bleed on #7 side.

Just pulled the plugs on the drivers side and they were progressively darker towards the rear. I did try stagger jetting 2 sizes leaner on left rear and right front once. Didn't see much difference, but have never tried 5 sizes leaner.

Just for info we had similar problems with an old 440 -3 manifold where # 1 and # 2 (to a lesser degree) ran lean. The info I managed to gather back then, was the then current 440 -3 did have a distribution problem. We switched to a -3X and solved the issue picking up a little H/P on the way. Pretty sure the 440 -3 manifold is now a different design but the one I had back then just looked like an opened out 4150 manifold.

Good to know. I will be installing an Indy tunnel ram soon and i will see if this issue goes away.

There was a post a few months back discussing the distribution issues of these manifolds, and others. I remember BradH posted some of the testing he'd done in it, along with others. I will have to see if I can find it.