Need to find TDC on 100E engine

enfoprefect · Post by **enfoprefect** » Tue Mar 06, 2018 10:11 am

My 1948 Prefect has a 100E engine. To retain the motor mounts, it has the timing cover from the original engine with no timing marks, of course. How can I find exact TDC on a sidevalve engine so I can add a timing mark?

JAN · Post by **JAN** » Tue Mar 06, 2018 11:00 am

Not easy as the pistons are not visible through the plug holes.

The 10hp engines' timing was determined by a pin screwed into the timing cover. This was unscrewed and turned around then pushed into the hole and pressed inwards and the engine slowly turned by hand. When the pin moved inwards as it engaged an indentation in the cam sprocket, that was the basic timing position. The 10hp cam sprocket is one of only two parts used in the 100E.

enfoprefect · Post by **enfoprefect** » Wed Mar 07, 2018 9:32 am

So does my 100E actually have the dimple in the sprocket? I always thought it did not. Having the front cover from my original engine, I still have the pin. If it is that easy then I'm almost home free.

JAN · Post by **JAN** » Fri Mar 09, 2018 9:09 am

Yes, it should be there. Part Number E93A-6256_A.

enfoprefect · Post by **enfoprefect** » Fri Mar 09, 2018 9:45 am

Thank you many times. For some reason I feel like I should have known that all along. Anyway, now I do and can quit worrying about it. No mark needed. YEA!

JAN · Post by **JAN** » Fri Mar 09, 2018 1:22 pm

No problem; it's what sites like this are good at - sharing knowledge.