clark 664 torque converter question

[rockwall]

A friend has a 1979 clark 664 and it started not developing full power. He had a really good detroit mechanic tune the 353. Is there a test to determine if it's the torque converter? Thanks

[treeslayer2003]

run it up against a tree with the foot board out. if the jack shaft stops with out the wheels spinning its either the converter or engine tune.
test the charge pump for pressure, 200 min. make sure its full, check hot idleing.