[Amc-list] Frankenstein 390 problem
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[Amc-list] Frankenstein 390 problem



I'm helping a Jeeper with a problem. He bought a CJ-7 that someone's Dad put together with a 390 in it.

I hear you all groaning already.

Anyway, he had no knowledge of the motor other than it had been built up some and hauled ass - for a while. It developed oil issues at a rather low mileage after being built which turned out to be bad bearings. The culprit? A 360 flywheel and possibly incorrect balancer as well.

Through the course of disassembly, we have:
-390 block of unknown year
-304 heads (by the casting #) that have been modified to an unknown extent (aside from possible mating to 390 depending on block year), as the heads have not yet been disturbed. 1970 390's were the only ones dogleg heads would bolt directly to, correct?
-1970 401 crank
-1972-up? 360 flywheel. Movement was noticed upon disassembly, so that's why we figure 72-up. That was the changeover year, correct?
-Unknown harmonic balancer, but I have it (and part number) at home.

I think you can all see what happened here. He's out of town and gave me the crank/bearings/balancer in order to get started on fixing this. I don't yet know if the crank can be saved. Its not smooth anymore, although nothing was spun. I was handed $250 to get started. The courses of action are:

1. Buy new or reman crank kit and flywheel. Sell the crank to someone that wants to care for it. Probably not going to happen based on crank availability and/or price.
2. Fix the crank, buy correct flywheel & balancer.
3. Fix the crank, buy crank/flywheel adapter (IIRC, I read about them here), and have it all balanced out.

So, who has suggestions? Can anyone recommend a reputable shop in the Detroit area thatI can take the crank to for assessment? I'd also like to find a source for 71-down flywheels. Third, does anyone know what brand flywheels Bulltear sells? I inquired and they failed to respond. They're at least $60 more expensice than the Omix units one of the local 4wd shops sells. Feel free to email me off-list, unless you think it would be informative for the masses.

Regards-
-Spro
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