Rod condition: how to tell?

[Ho Hum 74]

Hi,

I'm trying to determine the condition of one of my rods. The #3 big end bearing wore down through the copper and hence my rebuild.

My bearing is scored a little, but I don't know how much is too much. Is this as important a surface as the bearing itself?

My other issue is that the part number on my rod does not match the part number of the rods in Wayne's book.

My rod part # is 911.103.105.0R

Any clue as to what rod I have? It weighs 660g.

Tristan

[Steve@Rennsport]

Tristan:

Porsche installed rods by weight groups and you'll have to see what the others weigh. You might need another one, depending on the weight differences. Regardless, they should all be balanced.

The only way to tell much about rods is by measuring the big ends for roundness and inpecting the small end bushings for wear.

When using stock rods in any 911 rebuild, we always install and fit new small end bushings and resize the big ends so they are round again. Further, we make sure that the center-to-center dimensions are exactly the same as stock rods vary as much as .020.

These variations in rod length really affects deck height.

[Ho Hum 74]

Thanks Steve,

I have new small end bushings, but it sounds like I should have the entire group of rods evaluated.

PS. The only "code" I can see on the rod is '314' or '914' on the bottom end. I take it this is rod code 31?

Tristan

[Wayne 962]

Those numbers are casting numbers - not part numbers, FYI...

The rods need to be reconditioned - unless they are bent, they're usually very robust. Reconditioning will bring them back into spec...

-Wayne