Tim,

The Fox 29x and 35x engines had the same stroke, .700 inch. The 35X had a displacement of .352 cubic inch. Duke stroked the engine slightly, to .715 inch, taking it up to .359 cubic inch, making it a 36x and taking it  close to the combat limit of .36. The crank from a 29x would surely go in a 36x, making it a 35x. Putting a 36x crank in the 29x might reduce the clearance between the piston and the head to a dangerously close level and thus would call for that clearance to be checked. Another head gasket (or a thicker one) would correct the situation.

The inner diameter of the needle bearing is presumably half an inch, the same as the outer diameter of the crank. But I've never seen anything on these, or other, message boards about anyone successfully removing that bearing. I don't think it's the same as removing a ball bearing, e.i., heating the case and tapping it on a wooden block. Hopefully we will never have to deal with the issue!

Bob

Cheers guys,

I recently fabricated a 32thou gasket (see pics) for the 29X as the original was leaking. This thicker gasket has lowered the compression slightly, thus detuning the engine a little (I also used a thicker paper gasket for the backplate as it was fouling the crankpin!).

I've found a supplier for UNC bolts and bearings in modelfixings.co.uk, but as for now all the needle rollers are fine.

Ironically when I initially bought the 29X, it was seized solid bearing and all. - After it's last rebuild however, the bearing had freed up although the crankshaft now has a nice polished part where the seized bearing was!



Tim