[79blazer]

http://www.misterfixit.com/deton.htm I think a hotter would make it worse. I put the coolest t stat for a cheep fix. 165* And I am starting to get preignition back again. So I know I should check for Lean mixture (vac leak, egr, carb) Hot temperature (air intake, coolant) Octane (engine should run fine on 87, but I think it is trying to predetonate on 91) Carbon (valve guides do leak) Cooler plugs may help too, but want to know what kind of carburator this is and I have tryed looking. Does anyone know? thanks