I'm replacing worn valves and guides on an Hercules IXB-3 motor. Manual calls for hot clearances of .006 intake and .008 exhaust.
The magneto has been swapped out for a distributor on this engine making it impossible to access all the tappets. Anyone know what the clearances can be set to while the engine is apart.
Thanks
On some OHV enginss I heard to set them .002 loose, but this is not the same. It is a small engine, could you put it in an oven at 180 degrees for a couple of hours?
That's a thought;
When the new valves arrive, I will mic a few cold and then pop them in the oven. The cam followers or "push rods" aren't that long so the greatest gain from expansion would be in the valve.
The iron block expands with heat too. I cant say how much, but when making casting patterns for iron I asssume 1/8 inch per foot shrinkage when cooled. Hence my idea of hearing up the whole thing to operating temperature. It couldmalso be done by running hot water throught it.
There is a rule of thumb, but I can't remember what my gramps told me. It should not be too much different for a flat head as you don't have a lot of linear expansion. Check with another flat head engine of the same size, such as an Allis-Chalmers B or Continental.