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Bessemer FC valve timing


Hey all,

Anyone familiar with the valve timing on the Bessemer FC? I was adjusting mine and came across an issue.

The intake valve is fine. There is just a little bit of valve lash, and it opens and closes when it should (18 degrees BTDC and 12 degrees ABDC) and has the proper valve-open duration (210 degrees).

However, the exhaust valve (adjusted with a little more lash than the intake) opens around 70 degrees before bottom dead center and closes about 17 degrees before TDC. This gives it about the proper duration (230 degrees), but the whole event is about 45 degrees early.

I cannot adjust the timing of just the exhaust valve because both valves operate off one cam. Also, if i adjust in the pushrod to make it open later, that also shortens the duration of the event so the valve closes even sooner. That also gives it a huge valve lash gap of about 1/2".

I thought that the sideshaft might be one tooth off somehow, but I don't think it is because the intake valve is timed fine. It isn't super easy to take apart the sideshaft gear drive housing to verify timing marks so I haven't done that yet.

I have measured the degree positions by finding TDC and BDC, measuring the flywheel circumference, and finding inches of circumference per degree, and making marks on the flywheel to denote the timing, so i'm fairly confident in these measurements.

Any ideas?




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It surprises me that the intake has so much duration. Where did you get the specs to know that the intake is correct?
Is there a chance that someone in the past had it apart & reversed the cam on the sideshaft? I'll check my 40 hp settings if that would help. Bill Klein


I just did some research on google about valve timing and found a diagram for timing on "low speed" engines. I figured even if it wasn't right, it would be close.

The engine doesn't look like it's been apart aside from the piston (for rings i assume), but either way I think the cam is symmetrical. There are two dog bones that hold the cam end of the pushrod that are different lengths and i thought those might have been reversed, but an identical engine at the Kent museum is the same as mine, with the short dogbone on top and longer one on the bottom.