70 Still getting hot, what else to look for?

340_833 dart said
Are you using a factory electrical temperature gauge or a good mechanical gauge?
Are you confident your gauge is accurate?

Autometer electric gauge, been using the same one on two other engines and it has always seemed accurate.

green1 said
Seepage- the water stays cooler under pressure.

Yeah the intake does seep around the thermo housing, I have a new Air-gap intake sitting on the shelf, but I wanted to to heads at the same time.

2 Darts said
Just a wild guess. Did you have the block boiled out before you re-built? If not, you may have the same issue I had.

Yeah, block was boiled out, it was clean when I put it together.

69swinger340391 said
As mentioned before, check your timing. Not enough initial advance will cause it to run hot. Retard the timing enough, and it will overheat uncontrollably.

Did you do a cylinder leak down test? Remove the plugs, pump compressed air into the cylinders one at a time, remove the rad cap and look for bubbles in the antifreeze. This would indicate a head gasket leak.

What strength antifreeze are you using? a 50/50 mixture is best. If there is too much antifreeze, 70% or more, heat transfer is very poor and it will run hot and overheat.

You can use pure water (best for heat transfer) for short term testing, which will let it run cooler, but the antifreeze is needed for corrosion as well as the freeze protection.

Hope this helps

Haven't done a leak down, I'm running 50/50 Peak antifreeze, I plan to try the timing this weekend, whats a good base to start with? I think I'm running 12 degrees now.