fouling plugs

[sprecks]

Hope you guys can help me out. I am having trouble with fouling plugs in my hemi. The same plugs are the ones fouling. It is always #2, 4, 6 and 7. #1, 3, 5 and 8 are always good. I have replaced the control module, coil, cap and rotor. I just made a 70 mile run on the interstate after replacing the plugs. When I got back I pulled the plugs and 1, 3, 5 and 8 still looked brand new. The usual plugs were black again. It seems to be fuel fouling not oil. I have mopar performance electronic ignition with an orange box. Dual AFB carbs, 472 CID, 9.5 compression, running 92 octane gas.
Any suggestions? I haven't replaced the plug wires yet.

[brads70]

I'm no expert but could you put hotter ( heat range) plugs in the rich cylinders?

[MEK-Dangerfield]

What intake are you running?

[sprecks]

I'm no expert but could you put hotter ( heat range) plugs in the rich cylinders?

I forgot to mention the heat range in my previous post. Stock heat range plugs are RN12YC (Champion). I am running RN14YNC right now and it hasn't helped.

I hear what you are saying too Jason. I really hate to start modifying the intake manifold though. It has an original hemi 2 x 4 intake on it. Maybe there is a different intake I should be running.

Any of you Hemi guys running into a similar problem with fouling plugs?

[Cooter]

How to we know that 1,3,5, &8 aren't running too lean? I've NEVER seen a dual four set up run completely clean on the plugs to where they are "Brand new".....

[sprecks]

How to we know that 1,3,5, &8 aren't running too lean? I've NEVER seen a dual four set up run completely clean on the plugs to where they are "Brand new".....

Good point Cooter. Any suggestions on how to equalize the fuel mixture? I couldn't believe it when I pulled the plugs and they looked brand new. I planned on posting pictures but the uploader is full.

[Moparal]

You are sure you have no internal intake gasket leaks?  Does it clatter, ping or smoke under wide open throttle?  How are the guides? Maybe try swapping the carbs if possible and see if # position changes. I have that 1500 page Mopar book that gives some tech tips on resolutions for stock stuff. If I can remember, I will browse through it in the intake tune up section

[sprecks]

You are sure you have no internal intake gasket leaks?  Does it clatter, ping or smoke under wide open throttle?  How are the guides? Maybe try swapping the carbs if possible and see if # position changes. I have that 1500 page Mopar book that gives some tech tips on resolutions for stock stuff. If I can remember, I will browse through it in the intake tune up section

It does smoke when you first get on it. I just figured it was from loading up. The heads are fresh with new guides. No pinging. It looks like it may be time to pull the intake and check for internal gasket leakage.

[Moparal]

when some machine shops install new guides, they have to hone them. And sometimes they are too loose. I wonder if they installed the rubber o rings on the exhaust valve stems? This helps fouling as the guides wear. 2 big issues are internal oil leak into intake and guides.

[brads70]

What about an MSD box? I know some on the board are not big fans of them but they have always worked great for me?

[mojavered]

What carb are you running?  It is possible that the air bleeds are clogged up.  I had a problem with my #'s 5 and 7 fouling and it turned out to be the air bleed was clogged.  Worth a look, just be sure not to drop them down into the intake if you remove them.

[Moparal]

he's running 2 AFB carbs

[mojavered]

Thanks Al.  I even looked at it twice.....But there it is, right there.

[mopar12372]

if you have a after market , headers , intake , carb , ignition , you should go 1 heat ranges cooler on the outer  plugs  2 on the inner because the exhaust ports are close together ,most people just do the 2 cooler all around.

[Bullitt-]

It would be interesting to see if there were a significant difference in the resistance of a plug wire that was fouling compared to a similar length wire from one that is not fouling.