Connecting Rods

philster

I have been asked a question by a fellow club member in Aust.  Are con rods interchangeable between 1934 to 1939 Hudson, Terraplane 6cyl to 8 cyl?
Looking at my manuals, the C - C is the same at 8 3/16" and the weight for 1934/36 is 29.4oz, 1937/38 is 30oz and 1939 is 30.75oz.

Looking at the data, providing you use the same weight con rods, then I can see no reason why they are not interchangeable.

Am I correct with this assumption?

Regards
Phil

Frankvintagefullflowcom

Phil,

You are correct but there are a few things to watch for. 212 and eight rods are the same but, of course, the six has three rights and 3 lefts, the eights 4&4.

The weight difference is due to changes from shimmed caps to non-shimmed and/or the thickening of the rod "shoulder" area in the '38 and later units. Also be aware that the 175 and 212/254 rods look the same at a glance but the 175 rod is 8-5/8 long. I guess you know that already.

I believe the part number for the early rods is superseded by the later number: 44704-5 is superseded  by 157363-4 and both are superseded by 166241-2.

Frank

Geoff

Frank, as always, is right on the button!  The parts interchange catalog shifts you from the early rods to the late rods progressively, and you can use any of the 5" stroke engine rods, in any car from 1934 to 1947, and 1952 for the eights, but as Frank notes, not the 175 c.i. motors.    I have used a 1938 rod in a 1930 model Essex, but you can't do the reverse.  From 1934, when they went to 5" stroke, the rods had a scalloped out section on the right hand side that was designed to give clearance of the cam.  If the cam gear gives out, then you can get a fatal collision between the cam and the rod.  I have seen a camshaft broken because of this.

Geoff 

Frankvintagefullflowcom

Geoff,

Thanks for the credit. As always, I recommend that one NOT use the fibre cam gears in the 212 and I know you'll agree. The '42 C-6 I learned to drive in around '63-'64 had that happen when my Dad was travelling from here to Sea-Tac airport (about 60 miles) on a dark, rainy night. It took half of the cam out and stuffed it into the dipper tray and seized up the whole works. Lucky he didn't end up over a bank somewhere. The steel hub separated from the fiber gear. Back then there were still lots of engines around in wrecking yards for cheap, so Dad fixed it.

F   

philster

Thank you Frank and Geoff for your input.

Regards
Phil