[glfredrick]

Man, your story is sounding like deja vu all over again...

I replaced the 240 I-6 in a 1970 F 100 with a newer 300 and had a lot of the same issues. I went around and around with the salvage yard - they saying I didn't know how to install the spark plug wires - me saying that the engine was screwed... Ultimately I discovered that the head was cracked and it never would run right - I ended up with 3 motors before I got one to run.

I would rebuild the carb - it is likely leaking into the manifold - check the torque on the manifold - make sure that the EGR isn't sticking (if it has one) - and make sure that you don't have the wires 180* off. (A Ford 6 will run that way - but poorly!) Also make sure that the exhaust isn't plugged (I know you said it was making smoke - but trucks that sit sometimes collect vermin in the exhaust pipe - I sure scared the family in my truck one time - I launched them over 50 yards when they finally came flying out!)

 

[glfredrick]

The interior passages in the carb - idle circut, etc. - are likely plugged with varnish from the old gas. The cure is to soak the carb in carb cleaner, then insure that all the passages are clean. If the idle circut cannot flow correctly it will siphon fuel through the main circut.

Also, is there a free source of air into the engine - to provide venting for the PCV? It is possible that you are drawing too much vacuum and that is siphoning fuel out of the carb.

That is about the limit of my knowledge - anyone else out there have any ideas?

 

[glfredrick]

Wow...

I'm glad you figured it out - and thanks for the further tune up tips.

I feel your pain - in the one I did it wasn't multiple carb rebuilds - it was multiple engine installs - It took 3 before I finally got an engine that worked from the junk yard (I never mentioned the first one that had the timing gear blwon al over the inside of the oil pan...).