Have a 1975 F-100 4x4. Motor is a 390 4V from a 68 Galaxy. The motor was changed to solid state ignition (elecronic?). It orginally had a point distro. I set the plug gap to .035. The number 4 cylinder plug was taken out by hand. It was not even close to tight. The top of the #4 cylinder looked like it had oil and crud on top. I figure the plug was not even firing. Is the blue smoke on the right side, due to the stuff burning off the piston? It has been ticking under the valve cover, but does not get worse under load. Seems to run fine. Any sugestions would be great.

 

blue smoke is a sign of oil burning, so I suspect the cylinder is firing correctly. (if it wasn't firing, nothing would be burning) The problem is that oil is getting into your cylinder, probably due to a bad valve seal.

 

If it seems to run fine now that you found a loose plug..it very well could be just burning off residue off the piston and cylinder...run it for a bit,change the plug if needed and run it some more..

See if it clears up! If it doesnt you'll need to take a compression test!

Keep us posted..Good Luck...Russ

 

Mine does the same thing, minus the tick. I rebuilt the motor in Feb and since then, haven't used a lead booster in my fuel. My right side side smokes and my left side is starting to. I'm pretty sure my valve seals aren't hardened so I've messed them up with unleaded gas. I also believe that I have a bad head gasket that's allowing oil into the #4 cylinder. I've checked and the #4 cylinder is the only one getting the abundance of oil. The only way I'll be able to actually verify this is when I pull the heads and get them worked. We'll see.
If you just aquired this engine, you might want to pull the valve covers and make sure the rocker assemblies are tightened down. I bought mine from a friend of a friend and he told me that the motor had just been rebuilt. I had ticking so I checked and one bolt was out 1/2 inch, and it wasn't even the right bolt. Identify the oil port rocker stand (3rd from the rear on the left, 3rd from the front on the right) and make sure the bolt is different from the others (I don't know the technical name for it--Help).
Maybe this helps you.

 

Thanks everyone,
This weekend I'll go run it for a while and then pull the valve cover