amc javelin 390 into j-10?

[Yoder]

would a 390 out of an 1974 amc javelin fit into my 1977 j-10 with a stock 360?

[Elliott]

It's a direct bolt in.
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*Oh yeah, bolt on the correct flex plate first and add the TH400 bushing in the end of the crank, then the end of the crank may or may not need the spacer ring for the TH400 TC (if needed, available off the end of the crank in your truck provided you have an auto tranny in your truck). ;)

[ January 01, 2004, 04:09 PM: Message edited by: Elliott ]

[Bob Barry]

...if AMC had made 390's after 1970. The crank flange on AMC motors up to '71 was configured to work with a Borg-Warner automatic. It needs to be machined to work with a TF727 (which would have come in a '74 Javelin), and by extension, with a TH400 transmission. I honestly don't know what Jeep did to mate the crankshaft to a TH400 in the '71 FSJ's.

If the crank has already been machined, then it would work. If they swapped in a Borg-Warner automatic, you may have to have it machined to work with your tranny (which do you have?).

The other thing is the head-ports on a '68 or '69 390 are rectangular, and won't mate up to the dogleg ports on your '77 exhaust manifolds. The deck-height difference of the '69 and earlier motor might also make for a problem if you keep the stock Y-pipe.

Find out what that 390 originally came from, and what tranny it is bolted to at the moment. Then you'll have a better idea.

[Elliott]

I'd use the manifolds that came on the 390 and have a custom y-pipe built.
On trannies I was figuring you were going from TH400 to TH400.
Nice motor btw!

[ January 01, 2004, 03:45 PM: Message edited by: Elliott ]

[Crazy_Jeepman]

Not a Direct Bolt in. Are you sure its a 74 390? Maybe a swap into that car? I do not think 390 was manuafactured after 1970. At anyrate finding out before you get involved would be best advice. Finding a Flex Plate Balanced for the 390 and able to mate to the TH400 maybe some fun.