pyrometer reading question

[stevek]

I am finally getting the hang of flying my boat and noticed that over 5k the pyrometer reading is about 100 higher on the left bank vs the right bank. The left bank goes up to around 1300, the right stays right about 1200.

The motor is a 95 2.5 245 carb. The gauge is a Gaffrig that reads both banks.

Is this normal or is it time to for further diagnostics and a rebuild. I had planned on having it rebuilt this winter. It has over 100 hours on it (based on info from previous owner).

Thanks,
Steve

[Markus]

I would guess your left bank is really rich and that the pyrometer gets flame broiled.

[halveb]

If the probes are installed in the lower bolt locations on the exhaust plate that may account for some of the difference. I have a 2.5 260 EFI and installed my probes there per directions and was very careful to get them installed the same depth and they are about 100 degrees apart.

Try switching the probes and see if the difference remains, that will ensure that it is something with the exhaust gas and not the probe and its position in the exhaust chamber.

If I am not mistaken the cylinders are also in different locations (i.e. one bank is higher than the other) unless you gotta a new fangled special crankshaft. That is probably the biggest reason for the difference (proximity to the flame).

[stevek]

Thanks guys.