340 External Balance Run Stand

mostrood said

Hi, Im finishing a mild '72 cast crank 340 build and want to break it in on a runstand. Whats the cheapest solution for starter connection? My cars auto so I dont really want to buy a $300 ext balance flywheel for one start up. Ive heard of cutting open and using 1/2 of a torque converter which sounds good except what about the external balance part? Seems like an off balance mess. Thank you

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The imbalance for a specific app is welded to the converter face. If You would cut the weld as would be done to rebuild it, & just leave the guts & pump side off, it would still have the ring gear & imbalance needed. BUT, You'd have to cut a much rarer cast 340 converter up, so there's that. B&M probably makes a flexplate to use with all neutral-balanced aftermarket converters, but You still need part of a converter just the same.
Honestly, to run it on a stand at cam break-in speeds, & check for noises/leaks, the imbalance is a non-issue for You. There have been some used OE flywheels on here in the Mechanical Parts For Sale Forum pretty reasonable, they'd do just fine