Hello, The tool is stamped Sunnen Products Co. St. Louis , MO. Any insight as to what this would be used for? Appears to be some type of cam locking clamp. Overall length in the closed position is 12-3/4". The smallest opening (with the cam lever down to the handle) is 3/4", and the largest is 3-1/4", with 4 other settings between. Thanks, Lou

I am wondering about that unexpected bend on the end near the handle.

Hello, Northwoods. It looks original, no sign of damage, if that is what you are wondering. Thanks, Lou

 if I recall right, Sunnen made a lot of automobile rebuilding tools.

could it be to hold a piston to assemble the rod ???   NOPE !  just checked.

VALVE SPRING COMPRESSOR, patent # 1,720,802    Dec. 18, 1926

That's a complicated valve spring compressor compared to the one handed plier types.
I don't think they sold a lot off those. First I've seen.
Thanks for the post

From DATAMP:

"Marked SUNNEN PRODUCTS CO. - ST. LOUIS, MO - PAT. PEND. This spring compressor was advertised in the April 1927 "Chilton Catalog and Directory". It fit springs on several six-cylinder engines, and came with a set of six clips to hold the compressed springs."

Lou, you probably didn't find the 6 clips with the tool?
Al

Hello Guys. Thanks for the info. No clips, what you see is what I got. Thanks again, Lou