connecting rod questions

[targa72e]

Hi all,

I was recently going thru my stash of 2.4/2.7 rods to select two good sets for some future builds. in measuring and weighing several sets (26 rods total) I noticed a couple things. First most of the rods had weights with nuts between 690 and 700 grams. However one of the sets had weights that were significantly less with weights around 670 grams. I know from the spec book that there was quite a variation in weights possible.



the other thing I noticed with this set of rods was that there were numbers stamped on the inside near the parting line (these are stamped not imprinted stains from bearing shells). none of the other rods had any number stamped here, Thoughts? Here are some pics of the rods.








In weighing different sets I found one set that was all within 1/2g and when checking overall weight end to end weight these were within 1/2g as well.
Most of the other sets had a much bigger weight variance of 5 to 6 grams.

So I was wondering did Porsche do some additional selection at the factory? Did S engines get lighter rods that were more closely matched in weight and T engines got the heavier rods with bigger variation?

thanks,

john

[Bigtoe32067]

I don’t know the answer but I’m subscribed to find out the answer to this very interesting question.
Tony

[faapgar]

Those are transferred from the back of the bearing.It is the part #.Ciao

[Mark Henry]

Originally Posted by faapgar

Those are transferred from the back of the bearing.It is the part #.Ciao

I agree, I see it all the time. Also good indicator that the big ends need to be resized.

[proporsche]

Mark you are saying if you see these marks from the main bearings you need to go oversize on the crank bearings??
Ivan

[Jeff Alton]

^^^^ No, the big end of the rods need to be resized back to standard.

[Mark Henry]

^agree, "resized" is a generic North American machinist term, for rods it means resized back to standard.