Hey guys during my motor rebuild, apparently I let one of my irons develop some small rust spots . They are right along the wear lines, do I need to have the iron lapped?

 

You should have them lapped anyway.

 

and why?



rust is superficial unless it has setup deeply that it causes severe pitting. clean it up with some steel wool and if the pitting isn't bad then it should be fine to reuse.

 

other than the small rust spots, my dial indicator shows that they are within spec

 

Not true at all. Lapping is only necessary if the housings are worn out of spec, or the surface is damaged. Lapping any '85 to Pre-Renesis irons results in the coolant seal groove getting shallower each time they are lapped. You can only lap a few times before this groove is unusable. Also, lapping is a pain in the butt and expensive. It also removes the nitride coating, making the surface MUCH softer and thus more prone to wear.

If there is just a little surface rust, take it off with some 300 grid paper (wet). If it's pitted, it's probably still fine as long as the pits are small and not very deep.