Thanks for all the suggestions, work took me out of town for a few days, so I am just getting back to working on this. I have a 50-50 mix, shroud in place, well burped several times, (got a T in the heater line to help) plugs look good, timing is on at 0 with distributor lines plugged, HAC systems bumps it to 12 BTDC when plugged in. Vacum pump on the distributor line moves the advance when I test it. Have had the distributor out, but can't imagine it would even run if I was a tooth off. It is not getting into the red, but does run higher (2/3 to 3/4) than it used to when it is working hard. If I engine brake going down a hill, the needle will rise. If I let it coast, needle plummets to 1/3 quickly. At idle or around town it will hold at 1/2 all day. I am thinking about dcg9381's suggestion re detonation. Its got me thinking I need to maybe check out the EGR system. I think I have eliminated everything in the coolant system and need to start thinking about other causes. One scary thought is a possible coolant or oil passage is plugged in the block? Soon as I get some free time (and after it cools off a bit, 95 degrees today) I will be back in diagnostic mode. Whew, long post, thanks again for the suggestions. <img src="/forums/images/graemlins/cheers.gif" alt="" />