Spark Plug Fouling Right Vs Left Bank

I am getting significantly different plug fouling on the right vs left bank. The left (driverside) bank runs much leaner than the right. I've leaned the jets down to 48s right now (remember I am at over 5000' here in Denver and drive 5000-12000'), and the left bank seems to be spot on - I get a light grey color and the plugs are nicely clean, even after a mix of driving conditions and wheeling and ranging from my house at 5,000 to over 10,000 and back. But the right bank shows heavily black sooting indicative of very fuel rich - its a dry carbon sooting (no wetness or oil). The right bank has seemingly always been richer than the left bank since the rebuild and as I have slowly gone through the carb and turning process. I think the 48 jets are spot on based on the left bank, but need to figure out what is going on with the right bank.

The 225 is 60 over with new comp cam (252 grind), original intake manifold, and 2g carb that has been taken apart, cleaned, new gaskets, main jets, PV, accel pump, and idle mix screws. Basically, I am trying to determine if this might be a carb issue feeding unequal amounts of fuel into the manifold, a spark issue, a manifold issue (such as a leak?) or something more internal (cam lobes - although its not a single cylinder, its the whole right bank). Although its more of a secondary issues, plug 6 is always slightly less sooted than 2 and 4, but all 3 still indicated way too fuel rich. Driving wise, this issue is not noticeable unless at high elevations (say over 9,000') and its starts to show indicators of being too rich such as a rougher idle, occasional weak or mis fire, and more fuel smell out of the exhaust. Kind of stuff that seems pretty typical of high elevation change with carb. After 500 miles or so, the right side soot starts to cause a bit more consistent noticeable misfire at idle.

TIA!

 

Pertronix ignition with their 'flamethrower' coil (internal resistor).

 

What setup is your exhaust?

 

oem manifolds on each side into a y-pipe with single muffler/exhaust exiting rear.

 

Have you done a compression check?

 

The 'y-pipe' is more of a 'T', but its been that way for 4 years with no problems previously. Its probably not the best set-up for maximum flow but it works, its tucked up and out of the way pretty well, and its quiet (which is what I really wanted after the headers and glass packs from PO).

But now you got me thinking....I had some issue when I got the manifolds, they are not a matching set, and one side has slightly smaller ports (probably a true 225) and the other slightly larger (maybe 231). Wonder if the smaller ports are on the passenger bank and causing some issues when compared to the driver side. Never noticed before, but it was an old and worn engine.

 

No - maybe I can do that this week.

 

I believe Fino is saying his passenger bank is the sooty one also.