Connecting rod suppliers and other short block thoughts

Posted by Jack Vines On 2008/8/14 11:01:31

Greetings, Men-Who-Own-One,

In another thread someone mentioned the possibility of late-56 engines being made up of the sweepings from the parts bins. We do a lot of 374" and naturally, these are later build engines.

On a couple of performance engines we have in progress just now, I note three different manufacturers of connecting rods. "Atlas" is the only one identified by name. These also have cast-in Atlas 8, Atlas 9 and Atlas 10, all in one engine set.

Working with these mixed sets of rods is a royal pain, because they are widely varying in weight. There is a balance pad left on the forging on the top and bottom of the rods. On some rods, the balance pad is virgin; no grinding for balance at all. On others, the balance pad is almost ground away.

When doing a performance balance, all components to less than a gram variance, we're finding for all their bragging, Packard was pretty sloppy with static balance.

We've got six more 374" cores on hand. Maybe the easiest way is to pull all them down, sort out the rods, and try to make sets from the same forging foundry and re-number them.

Question: on '55 engines, is it more likely all rods in a given engine would be from one manufacturer?

Question Two: One P/N for 352" and 374" crankshafts. Anyone know differently? The 374" pistons are 38 grams heavier than the 352" pistons. We balance most of our engines, but what about the dealer ordering a replacement crankshaft? They definitely didn't rebalance, so which crank did Packard ship and did they have vibration problems as a result?

thnx, jack vines