[ed_h]

On my '71 T100R rebuild, I'm doing the rocker boxes. The rocker spindle seal is listed as part E3253 (it's called an O ring for the T100R and a "sealing rubber" for the T100C, but the same part number). The small O ring in the picture below shows what is apparently an E (70-) 3253. The larger rubber part is what came out of my machine.

As you can see, the 3253 is too small. The original part is also not a circular cross section. It may be hard to see, but it is definitely a rectangular cross section, roughly 0.031 x 0.062. I've seen O rings deform in cross section before, but this is too uniform and square to be deformation. The dimensions of the groove in the shaft are pretty close to the dimensions of the seal that came out of it.

Anyone know what the right part for this is?

 

[t100rc]

It's the right part. Believe it or not, that o-ring USED to look like that when new. Install it ... when it goes through the hole in the rocker box, it will 'cut' the o-ring and there will actually be a piece that falls out. There is a tool for installing it as well ... check your parts (or service manual) and they'll show the tool.