Hi guys I have a few questions on an 391 in a bluebird chassis circa 1969. Its a rv conversion with about 100,000 miles.

1. timing, I decided to check the timing and it seems any where the distributer is turned the marks dont drift much. Of course when I rev it, it back fires or runs like an engine thats too far advanced or retarted. It has a governor holley carb with vacuum advance and a vacuum line that runs to the bottom of the distributer from the carb. Im not at all familier with this setup and dont know how it works ( If any one can tell me that would be great) how do I time it?

2. the carb leaks fuel on the right side under certain conditions, at the 3 screw plate on some sort of vacuum plate. Not all the time but when the motor is warm and loaded ( Ive been there also years ago) haha my carb guy laughed at me when I said I wanted to rebuild it and said replace it with a 550 holley. Im not sure about that given the vacuum line to the distributer. The motor is hooked to an allison mt64. So should I chuck that dizzy and carb and go with some thing else? I dont mind the guv set up but dont like it leaking

3. whats the life of this motor, it was taken very good are of, it burns a little oil by the valves but has good power. (what little power it has) given 17 000 pounds to move

thank you gents

 

Is the carb & governor working OK? IIRC, the 391 should govern at 3400 RPM, and will do it's job under most conditions real well if shifted at 3000. If your "carb guy" can't rebuild it, time for a new "carb guy"- but if the governor stup is working OK, just leave it alone- if it ain't broke don't fix it. Many 361/391's have met an early demise because somebody got sticker shock from the price of a rebuilt governor carb when theirs probably only needed a set of gaskets, and stuck a little car Holley on it, then the driver starts running it up around 4000, boom comes soon
Put the timing back to spec ( easy enough to find online for your year etc, check to see if the advance mechanism is free and working correctly, and check the accelerator pump for correct adjustment. A little more description would help, backfiring from intake, exhaust, what? Intake backfire is probably the accelerator pump, easy fix.
If you don't know how to do these things, try to find an old truck mechanic that knows these engine, sounds like your "carb guy" is the "wrong guy" for this project. The governor setup works well when it's "right", but it's not something you can just "dink with" and get "right". A copy of the factory truck shop manual for that year or a Motor Truck manual would be a very good investment, try ebay

 

The timing chains and gears were a weak link in the FE and FT engines. Most if not all were built using plastic teeth on the cam gear and that gets brittle and breaks up with age and miles. I would check for bad timing assembly first and the way I found that worked best for me was to remove the dist. cap and spark plugs, then using a ratchet and socket on the bolt in the middle of the vibration dampner turn the engine one way and then the other. If you see that the rotor on the distributor only moves a little when you turn the crankshaft a lot you have a timing set in your immediate future. If the rotor moves right quick when you change direction on the crank your timing set is likely in good condition. Another clue would be to find plastic pieces at the opening for the fuel pump when it is removed. You can also look for plastic bits in the oil pan that may come out when you drain the oil.
If you are going to use the engine in a different application you should use the Allison transmission as they are almost unbreakable and almost anyone can rebuild them cheap.
Good luck with it and keep us informed on what you find.