Cylinder Soot
 

Got a surprise when I pulled the plugs to clean the outside of them. Numbers 1 and 2 were very clean however, 3 and 4 were sooty particularly #4. The engine has maybe 3,000 miles on a complete overhaul. I have had to change the exhaust manifold a couple of times but would think if the soot developed due to leaks it would quickly burn off. Also a newly overhauled carb. I tend to run it a bit lean until I get a pop after turning off the ignition then I open the needle valve up a bit. Ideas as to cause of the buildup on 2 cylinders?

Re: Cylinder Soot
 

I would worry about 1&2 running lean! Then adjust for a rich mixture.

Re: Cylinder Soot
 

Could be the intake manifold is not seating well around the cylinder 1 and 2 port, and you're getting a vacuum leak, leaning out those two cylinders. You compensate by opening up the GAV, enriching the mixture to get rid of the pop, but now 3 and 4 are running too rich. I'd recommend having the manifolds machined as a unit to make sure they are flat.

Re: Cylinder Soot
 

I do not know your experience level on As, so excuse me if you already know this info.

When reading the plug only go by what the ceramic insulator looks like. It is not uncommon for the rest of the plug to be black/slightly sooty. Look for a nice tan color, clean/pure white is too lean, black/sooty is too rich. When I first got my truck, had difficulty believing it was OK to have black and soot on the plugs with a tan insulator - was too used to modern cars, especially cars with electronic ignition and fuel injection.

Perhaps post a picture of your Plugs?

Re: Cylinder Soot
 

[QUOTE=30 Closed Cab PU;1946937]I do not know your experience level on As, so excuse me if you already know this info.

" Look for a nice tan color, clean/pure white is too lean, black/sooty is too rich. "






Well I'll be darn -- Thanks

Re: Cylinder Soot
 

What brand spark plugs are in use? All with the correct gap? The correct heat range type of plug? Do a compression check on all cylinders to see if they are all close to each other.

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