225 rich on pass side bank, lean on drivers side.

Hey all, merry Christmas and longtime no see. I've got my 225 in the cj 6 running but it's lean on left bank and rich on pass side. Weiand single plane,holley 390 combo. Vacuum steady at 17. Points ign w New points condenser and coil. Carb is not new but cleaned well and does adjust. Jets 48 in primary. 85 power jet. Slight stumble throughout rpm range.

any ideas?
Thanks, Frank

 

Not an expert on the 225, but I would check for vacuum leaks at the cylinder head first. Check with a stethoscope, or carb spray.

Does that manifold have a plenum under the carburetor? If so, it is unlikely from the carburetor, since the plenum is supposed to equalize the fuel supplied from each barrel. But a vacuum leak at the cylinder head would make one side or specifically one or a pair of cylinders lean. The front and back cylinders typically run a tiny bit leaner than the center cylinders, due to the geometry - but this should be minor.

 

No vacuum leaks, I figured same with open plenum intake too about evening out fuel delivery. I strongly suspect ignition somehow. Funny thing is, it will accelerate with no hiccups just slight stumble when not under hard acceleration and sooty plugs on pass side only.

 

Oh f-head how I miss your ability to run on pure varnish with 40 year old plug wires...

 

All of what timgr mentioned........Vacuum leaks can be an issue at the Carb. also intake manifold gaskets will sometimes leak between the valley and the head and intake manifold port surface.
Are you basing this Rich condition off just reading plugs? And what color are the plugs from side to side? And how do you drive this Jeep? Just reading plugs from a grocery driver that see's Idle and low speeds allot is tough to do.
That Holley Carb is a good adjustable Carb and there is plenty on the Holley sites about how to adjust and make them better............including taking out that stumble which could be and accelerator pump ramp or even the timing of the vacuum secondaries, check the float levels and also the gasket at the base of the carb. That is a spread bore carb and some aftermarket gaskets close off some of the ports in the base so make sure it has the correct one.
Best to take a new set of plugs and do some freeway speed and higher RPM driving for a period of time.......maybe a 30 + minute ride and then look at the plugs......Ignition is always suspect but unlikely on just one bank only but I can tell you the HEI aftermarket Distributors do wake up the old 225's as compared to there point and condenser relatives.........I would also do a leak down and compression test on all your cylinders............rich conditions sometimes are also valve and ring issues.

 

I ran into a problem one time that 1 whole bank on my v6 was cold and the other hot and normal . motor ran but very little power. since I have OBA I shot compressed air into the 2G mixture needle adjustment screws and that fixed my problem , the 1 screw had acquired junk in there.

 

Are you running a heat riser on the pass side?

 

Have you swapped the distributor recently?

 

Isn't it possible to get an odd-fire distributor installed incorrectly, so that 3 cylinders are timed correctlty and 3 are not? Maybe that's what's going on here...

 

I had this problem too. I checked everything and could never figure it out. The PO of that v6 had it so messed up that it never ran right anyways. I ended rebuilding another one and putting that it. Solved it real quick.

Pull off the valve covers and check to make sure the valves are opening properly, crank is over with the coil wire disconnected. The messed up v6 I had, had a rounded off cam lobe, just one of many issues it had...

 

Would the 8.5 power valve instead of 6.5 have anything to do with this??

 

Just a thought. Check mixture screw springs and taper. Make sure they're equal. Mine were different.

 

Those mixture screws are only in the idle circuit.

 

Just got a chance to get back online today. I used an 85 power valve because whenever setting up a holley carb I've always taken vacuum number (17) / 2 =8.5. The distributor was old, and has been out and in a bunch. I ordered a new one, will be in tomorrow. Does anyone have a pic of no 1 distributor terminal using hold down or point window toas reference. I've got a hunch the factory cap marking isn't correct. Plugs on drivers side grayish white, pass side sooty black. Not registered yet, no trips beyond chicken coop or sneaking up road at night.
Frank

 

Also, all cylinders are 160 psi plus or minus 1-2 psi maximum.

 

Found pic of no 1 on distributor same as mine. Looking forward to new distributor and pertronix.

 

The power valve is basically between the barrels, so it should not affect one bank over the other. I don't recall what Holley tells you to use, but they have a procedure to pick a power valve based on the vacuum readings.

http://www.holley.com/data/TechService/Technical/power_valves.pdf - looks to be the same as your method.

 

The numbers on the PV are half of what vacumn the valve is rated for. A 6.5 pv would be 13" vacumn. his is 8.5 = 19", and his engine is only making 17". I didn't know if that could cause his issues or not.

 

I really appreciate all the responses. Ill be starting first with the new distributor due to arrive today, and I will keep you posted.

 

I vote distributor. If it were carburetion it would effect all cylinders since you have a single plane intake.
The distributor you have coming is specifically for an odd fire 225 right?