distributor question
 

A friend just bought a 41 Merc, but it has what we think is a 38 Ford truck engine in it. The distributor has an extra "coupling" between it and the camshaft. I saw one of these on a 37 truck engine too, and couldn't figure out why it was in there. Is this something only done on truck motors? Is the cam shorter on them or what? It certainly wouldn't run without it, the shaft on the distributor wouldn't engage the cam.
thanks for any info on this
Jim S.

Re: distributor question
 

Which distributor is being used? Why do you think it is a 38 truck engine? It sounds like you have the short nose cam (42 - 48) with an early distributor, so you need the "button" to make them work.

Re: distributor question
 

He (the owner) had counter guy at a NAPA store check the part number on the cylinder heads and they said it was a truck engine - I don't know the part number but I could get it. He told me changed the oil and the drain plug was real big - like around two inches or so - the only drain plugs I've ever seen big like that were on tractor or truck motors.
The distrubutor is the type with two screws holding the coil - I think they are from 1937 - 1941. His didn't have the right coil, it had one of those adapter kits to use a more modern type coil. I have a bunch of distributor parts including a few of the tall looking 2 screw types that fit.
I can get his distributor to work just fine, but was curious about that button. I had never heard of the short nose cam - did they use the button from the factory or is this just a way of adapting a different dist. to these engines?
Jim S. (Sheboygan Falls area)

Re: distributor question
 

It was a way of adapting different distributors and cams. Not factory. The large drain plug is common. Cars as well as trucks.

Re: distributor question
 

41 Merc should have the 2" hex oil drain plug. You can not tell what engine you have from the heads. I am not sure, but believe the 99T head is correct for the 41 Merc. They are USUALLY marked in the cast iron in large numbers and letters.

Re: distributor question
 

99T heads are truck units with lower compression ratio to reduce knock under heavy cargo.