Motor Running Hotter On One SIde Then The Other

My Ford 289 has been discoloring the ceramic coated headers (especially the passenger side) so I got a heat gun to check how hot they were running and it turns out the passenger side is running over 100 degrees hotter then the driver side. The water temp runs fine never exceeding 180 degrees unless I get stuck in city traffic for a while or I am at a dead stop for a few minutes at a light which rarely happens (I do everything I can to avoid it). I have the timing set at about 12-13 degrees.

The first three pipes on the driver side are usually running in the low to mid 300's with the back pipe running in the low 400's, the first 3 pipes still look good with little discoloration and the back pipe only looks a little duller. The real problem is on the passenger side the first two pipes run in the low to mid 400's and the back pipe runs in the upper 400's. Pipe #3 on the passenger side consistently runs above 550 (the heat gun limit) a few times I was able to get a reading in the 530 range but most of the time it would exceed the 550 limit so it would not give a reading.

Does anybody know what could be causing such a disparity between the two sides of the motor and what I could do to get it to run at a more acceptable temperature that would not discolor the coating on the headers? Any help would be greatly appreciated.

I'll second the above, what kind of vacuum readings are you getting ?

What intake? Could your heads be mismatched? The rear cylinders are lean, vacuum leak at the back? Try some propane from a little torch, don't light it, just blow it around the gasket area,a leak will cause the engine to speed up.

Thanks guys, I am going to pull the hood off and do a complete check on the carb and intake. I have never liked the carb they put on this as it is a huge Holly 750 double pumper which is way big for a little 289. I was talking to the local Ford guy last night and he said with that large of a carb the motor could be loading up and the excess fuel is burning off in the exhaust so I am going consider changing the carb now instead of waiting till summer driving season is over like I planned. Thanks again for all your advice, it is much appreciated.

SBF's have a peculiar little situation. If you install the head gasket in the wrong position it blocks some of the cooling holes. If one of your head gaskets got put on backwards that could be your culprit.

There is an "F" on the gaskets, make sure that goes to the front. I don't know if that is what you've got, but this screw up has happened to all of us in the rush to put an engine together, and the problem is, the gasket fits either way.

Don