After getting my 406 sb running good i was playing around with my Raytek thermometor and monitoring the engine temp, and i noticed that the temp on some of the header tubes differ by almost one hundred degrees. What is that telling me? Exhaust valves to tight on that cylinder maybe?

Which tubes?

I dont recall off the top of my head. i just know there were a few that were hotter than the rest.

Originally posted by 70isfine:
After getting my 406 sb running good i was playing around with my Raytek thermometor and monitoring the engine temp, and i noticed that the temp on some of the header tubes differ by almost one hundred degrees. What is that telling me? Exhaust valves to tight on that cylinder maybe? 70isfine,

Usually we try to get each cylinder temp within 50 degrees of each other. If there is a variance, either one cylinder is misfiring, there is an A/F ratio difference cylinder to cylinder, or the measurement isn't totally accurate.

I'm not familiar with the Raytek thermometer. We measure our temps by installing a thermocouple probe in each exhaust runner being very careful to insert each the same depth into the exhaust manifold/header, and the same distance from the exhaust valve. That way we are getting a valid comparison.

Mike

The Raytek measures surface temperature with an infra red beam. I also notice when i first start it up,some tubes i can touch and they are just getting warm,while others are alreay hot enough to burn your fingers :eek: . So it could either be valve or mixture adjustment?

I wouldn't loose a lot of sleep over how quick it takes each runner to warm up, or temps at idle for that matter. I would be concerned that they are all pretty even by 1500 rpm or so.

Mike

Do you have exhaust crossover passages in your intake manifold? Seems like I took a heat reading off my engine when I had a Performer intake....and the tubes near the exhaust crossover were significantly cooler.

I see the same thing on my 355. It doesn't change with valve adjustments, etc. I think the fuel distribution is uneven, in my case, with a Performer RPM. I read a recent article in one of the mags about needing to do stagger jetting to get the mixtures closer to each other.