Xflow open plenum intake

[Rob King]

I am thinking about trying to run an open plenum intake on my Xflow, I know you have to cross jet the carbs but which bank runs lean?

Thanks Rob

[Robbie B]

Looks like you are going to have to "suck it and see"
What do you mean by "cross jet carbs"?????
Have heard that the bank that thrusts on the exhaust side of the piston needs to be a little richer than the other. STBD side, I think.
If you run an open plenum, won't all cyls get the same mixture???
Is your plenum design a common cyl 1 - 6 plenum or a twin system, ie cyls 1,3,5 & 2,4,6 plenumed seperately ( nice even pulses ), or are you looking at cyls 1 & 2, 3 & 4, 5 & 6, plenumed seperately???
Thought about trying something like the 1,3,5 duel plenum myself a while back.
Not enough hours in the day though.
Sorry can't be more help.

I've heard, in stock configuration, it was #4 and #6 and that it was from timing inaccuracy not actually hotter or leaner.

Cross jetting is making one side richer on one carb, on the next carb making the opposite side richer, on the next carb doing the same as the first carb (for 3 carbs). Staggered.

I wouldn't do that. I never seen or heard any benefits from that on 4strokes. Jet them evenly.

The open plenum will hurt low end but give gains up top.

-BL

[Rob King]

The intake is machined out between each barrel of the carb so both barrels feed at same time. I don,t know exactly why you have to cross jet but the guy I got the intake off of said that is the way to do it one bank will run lean, Racer said the same thing . Dont know why this is but if I had to guess one side draws off both sides of carb & other side does not pull off one side as much. Mabey one of the Xflow gurus will get on here & explain it to us.

Rob

[Robbie B]

Rob

Al Stoker will know what is required, if he says to cross jet, then cross jet.
Don't think there is anything crossflow that he has not done or tried, from what I here from people on this board.
I think I saw that L & S had plenum manifolds for flows, quite a few years ago now though.

BL

My motor runs cyls 5 & 6 leaner, I always jet all cyls the same to suit these two cyls.
Thought it may have been something to do with my ex system but you may have the true reason. ( variance in timing )
Have seen a V6 merc with a duel plenum system ( cyls 1,3,5 & 2,4,6 on seperate plenums) Had 4 std V6 merc carbs, two on each plenum.
Didn't run to good when I saw it going but heard that it finally got sorted and ran real strong, big revs on a big wheel.
Disappeared from the race scene shortly after, financial problems I think.