Bad intake Fuel/ air distribution or?

[zakimodo]

I have fixed a lot of tuning mistakes lately (learning from assuming things will work out of the box). Biggest change being that I had way too much mechanical timing (recently fixed by re curving the distributor) I also removed a MSD 6al after noticing a lot of timing walk at mid to high RPM (FBO in place now)
Admittedly through this I have been neglecting to keep up on reading all the plugs.
Pulled plugs tonight to see how things looked and noticed that the plugs from cylinders 1,2,5,7, and 8 are quite a bit richer than those pulled from 3,4 and 6. Any input on what I need to look at to get things balanced?
-Inake: Edelbrock performer
-Carb: Thermoquad
-Plugs: Champion RN12yc

 

[yellow rose]

That’s what that type of intake does.

 

[zakimodo]

That’s what that type of intake does.

Thanks. I knew dual planes didn't have perfect distribution, just didn't realize it was much.

 

[67Dart273]

Juz sayin checking timing on an MSD is a shakey deal. What you want is an old "non" dialup light

 

[yellow rose]

Thanks. I knew dual planes didn't have perfect distribution, just didn't realize it was much.

Just look at the cylinders that are the same. They will all be fed by the same plenum.

Then look at the other 4. They will all be fed by the other plenum.

 

[MOPAROFFICIAL]

As said.

 

[zakimodo]

Juz sayin checking timing on an MSD is a shakey deal. What you want is an old "non" dialup light

Yeah, I was using an old sun timing light that was my grandpa's. I may throw it in again and play around with this some more. For now, I can't say there was a performance change and I like the rev limiter on the FBO

 

[jbc426]

Juz sayin checking timing on an MSD is a shakey deal. What you want is an old "non" dialup light

This.

Also, if your timing continues to bounce around with a non-digital timing light.(I bought an MSD made light), a collar on the distributor shaft may stabilize it. Hughes sells them as do many hardware parts houses. It's just a 1/2" locking collar.

My MSD was also very far out of phase. I had to use the MSD adjustable rotor to get it back to where it should be. It was so far off that the added energy it took to make the circuit from the rotor to the distributor terminals melted the tip of the rotor and it fell off.

I've since pulled the MSD Pro-billet and replaced it with a bluetooth tuneable distributor from Progressive Ignition. I really like it, and I got my vacuum advance back.