Dual Plane Fuel Distribution

[furrystump]

Probably because you are slamming fuel into the plenum floor on the high side. Then raw fuel travels down the runner and never fully atomizes again. I have seen raw fuel stains on my plenum floor on the high side. I dimpled the floor to help atomized the raw fuel again. Staining was greatly reduced. You have the rumble strips to do it.

 

[furrystump]

I’m just a ham fisted monkey and NOT a porter, but I was told to round this edge as much as possible. To help the charge make the turn. This is not apples to apples.

 

[Valman]

I was told to round this edge as much as possible.

Those turns there have been blended with a larger radius, can’t really see it in the picture. Similar affect to blending a short turn in a cylinder head.

I thought about the dimpling, seems like there’s some mixed opinions about it. I may just try it for the sake of it next time the intake is off.

 

[furrystump]

You have the speed bumps already. The only thing I can think to try is using the smallest wire ties you can find. You put them on the booster with the ratchet on the outside pointing in the direction you want more charge to go, but you have a bank that is leaner. So that isn’t really a solution. Have you tried running a divided spacer? It could be due to firing order getting the charge moving one way and then having to reverse direction. But that usually just leans out one cylinder. I don’t see staggered jetting as a bandaid after you have done everything you can do prior.

 

[Valman]

You have the speed bumps already. The only thing I can think to try is using the smallest wire ties you can find. You put them on the booster with the ratchet on the outside pointing in the direction you want more charge to go, but you have a bank that is leaner. So that isn’t really a solution. Have you tried running a divided spacer? It could be due to firing order getting the charge moving one way and then having to reverse direction. But that usually just leans out one cylinder. I don’t see staggered jetting as a bandaid after you have done everything you can do prior.

I see what you mean. The aluminium adapter under the phenolic spacer has the divider, which has been smoothed to suit the manifold and spread bore carb.

I think you’re right about the firing order. The ‘5-7’ part may be pulling more intake charge over that side of the divider. I want to look at the carb primaries again, there could be a bit more transfer slot exposed on one side.

 

[Bewy]

Unequal T-slot exposure sounds like a twisted t/shaft.

 

[92b]

Seems like it would be a fairly easy test to stagger jet the carb and see if it changes the plugs.

 

[Bewy]

The MP bulletins might provide a starting point for stagger jetting.

 

[Valman]

Unequal T-slot exposure sounds like a twisted t/shaft.

Yes, that’s what I was implying. A slight twist in the shaft possibly. If there is, it wouldn’t be much.