Overheating 400ci
 

Help I have 76 formula 400 rebuilt by reputable engine shop 400 ci bored 30 over melling mtp-1 cam new water pump new 3 row aluminum radiator moly rings. Timing set at 24 degrees btdc per cam manufacturer. Keeps trying to over heat. Have 160 deg thermostat in it. Haven't let it get over 220 deg. Can't figure it out any input is appreciated

If it has the stock exhaust the heat riser butterfly may be closed

No it's got hooker headers un corked at the moment. Stock timming setting is 16 deg btdc we set at 26 deg. Because of the cam . It's bored 30 over. Wondering if we went to far on the bore. Got rid of the stock fan for a flex fan. Took it for a drive down freeway ran at 200 deg. Once we got off fwy it started to get go up again

Could the radiator be plugged? Maybe have it recored.
The 24 degree advance is the full advance using a dial back timing light?
What is the initial advance?

The radiator is new three row aluminum. Flow looks good. Stock timming is 16deg. Btdc called melling they advised to set timming at 26 deg btdc give or take a degree or two either way. Not sure what a set back timming light is but the initial timming was set using an inductive type timming light. The distributor is a MSD not sure what the advance is on it. The motor runs great no hesitation on acceleration no diseling at shutdown no pinging. Runs like the setup is perfect. Only heats up when sitting still or in traffic. And like i said runs at 200 degrees running down freeway at 65 to 70 mph.

Clutch fan?

Nope 16" flex fan

and using stock fan shroud about 1/2 inch of fan sticking out on engine side fan is about 3 1/2 inches from radiator

For testing purposes, set the timing back to 10 degrees and drive it around. If it still over heats check the distributor springs and try heavier spring or lighter weights.
Are you setting the timing with the vacuum advance disconnected and plugged?

FYI - A dial back timing light can show the initial adavance and total advance.

Yes we are setting timming with the vacuum line pluged. Stock is 16 degrees btc with the cam we put in it we were told to set it at 26 degrees btc by cam manufacturer. Wouldn't setting it at 10 degrees btc. Cause it to overheat faster. We had it set at 16 deg btc when we first started it and it got hot quick. It runs great at 26 btc it just gets hot when in traffic. Or at idle for longer than 10 minutes. The only thing we can think of is to run duel electric fans.