I put it all back together with a new bigger fan, no more hi temp at low speed. I diagnosed a definite exhaust leak, and tightened the adjuster screws about 1\8-1\4 turn past contact with valve. Any farther and the valve starts to open up. On #4 exhaust valve the lifter seems a litlle spongey. After tightening to this loose adjustment, I fired it up and two were still noisy so I shut them up with a 1\4 turn more and now can't hear anything over the exhaust leak, So I think cleaning up the adjuster nipples helped. After I fix the exhaust I'll be able to hear better. Thanks for the help.
