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Old AMC PN #321 6130 (Allows 727 to mate w/ the 390 crank)
AMC use to produce these, and I'm sure other folks 'll need them too.
I'm not really sure what they look like, just looking at the Performance American Style guide from 1980 & it's telling me I need this, it just gives me a schematic of how the crank needs to be machined. Please tell me you know what I'm talking about (I Cant find one & this $10.00 piece is whats gonna end up holding up the completion of my stroker project).
This adapter fits into the back of the 390 (or 290/343 or early 360) crank and the concentricity (how close to round it is) relative to the centerline of the crankshaft is totally dependent on the factory machining on the relief in the back of the crank. All that to say that you really need to check the runout of the adapter in the inside where the torque converter will seat and make sure it is within specs (.005" max out of round, I believe). Elsewise, you will ruin a front pump on the TF and have a very leaky seal.
If you note, the factory 'print says to machine these dimensions in place in the crank. I have seen a 390 crank that was almost .020" out of round and a 290/343 crank that was .028" out of round in the area where the adapter would seat. I have also seen them right on.
Uh, Now I get show my non-mechanical skills. What did you just say? I'm not the one doing the machining, my engine builder/machinest is doing it, he's the one that recommended I get the adapter, cause he hates doing the TF-727 to 390 crank mod without it, although it can be done. He's built (his words) hundreds of AMC engines in the past 30 years, as well as racing them too. Alot of the AMC guys in Kenosha (@ the show) and North Chicago area say that I'm in the best possible hands when it comes to an AMC build up. Don Schmitz (Owner of the Wally Booth race cars) said Joe know's his s*** when its an AMC engine. So I feel pretty confident in this build up. (The reason I need the adapter built is cause his machining tools are rough or something like that he said, not made for doing that type of work)
What does all this mean? Should I wait until the crank has been milled? Maybe I have to sent it to you? I'm not so sure whats goin on? This whole thing has me at a loss.... Please pretend like I'm (stupid) cause I apparently am, and put it into something I can understand.
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