I borrowed this picture, hope you don't mind Chuck.
I have to ask - what causes this buildup, and are there ways to minimize it?
It seems that some engines and different types of ignition systems are more prone to it.

 

I would think wire and plug resistance being high could cause more carbon buildup.

 

Hard to say. I've had some that get bad buildup and some that don't.

 

moisture is a factor aswell

 

 

I will have to try that next time on my truck.

 

Check the screen at the base of the distributor for being plugged too.

 

I would also guess moisture.

 

When you combine High voltage with anodized metal and throw in a dash of humidity, you will get carbon build up. Or, maybe it gets dizzy and throws up inside.

 

How much plug gap do you run? How many miles?

 

Indeed - larger plug gap will increase secondary voltage and erode all your points faster. Running the smallest plug gap that will do the job will put the lowest strain on all ignition components. The secondary voltage rises till it jumps the gap at the plug (or the cap/rotor if that gap is greater). That's why the plugs stop firing if the gap get a too large - the coil can't generate enough voltage to do it. Also puts a huge strain on the coil and the wires, etc. Prolonged excessive plug gap will destroy the insulation on wires and burn up coils.

GD

 

How much plug gap do you run? How many miles?

Just generalizing. It just that some vehicles do this more than others.

GD - remember those .060" and greater plug gaps GM used to recommend?

 

From what I understand, the larger gaps were to insure combustion with ultra lean mixtures that were notoriously difficult to ignite..... It's not a "performance" modification.... I have run .035 to .045 in virtually everything I've ever built of any make or model. You are generally always pretty rich when your trying to make power and it's pretty easy to ignite a nice rich mixture so I've never needed to increase a plug gap.

All it has to do is start the combustion. The shortest gap that will do this 100% of the time is the ticket in my experience.

GD

 

Does that finned #10477219 help to carbon buildup?

 

AFAIK it’s to help with moisture

 

Just ordered one.If it vented dist cap inside better than standard one it's worth it.

 

Not so much moisture, but ozone. The ribs are to help with ventilation, but to remove ozone, not moisture.

http://www.technicianstoolbox.com/in...x=4&topicId=23

http://www.farmallcub.com/phpBB2/viewtopic.php?t=6568

http://www.wellsve.com/counterpoint_issues04-06.html

 

Maybe some of us should connect a small vacuum line to our distributors???
I would be one to try it.

 

Have you ever examined a distributor for a marine application? The engines are the same. But the cap has a hole in it with a screen in it to allow moisture to escape. So why wouldn't it help get rid of moisture in an automotive environment?

 

add a vacuum leak and you will notice your idle go up.

 

On my Vortec 350 Express van I actually hooked up a small vacuum line to a port I added slightly above the throttle plate in the throttle body. I hooked a vent line to the intake duct. Anytime the engine was above idle it had ported vacuum to the distributor cap to purge out the moisture and ionized air. Went from having to change the cap and rotor practically yearly to lasting almost 4 years before the CNP 24x swap.

 

I am going to try this, but I will use a restriction in the vacuum line.
No need for a 20 gallon Shop Vac to be connected to the distributor.