1962 merc 450s fuel pump question

1962 Merc 450s Cloud White Serial #1511481
Recieved non-running and in poor shape though after rewiring spins and sparks with compression avg 115psi
across all 4 cylinders. Ive not attempted to "run" the motor until fuel and cooling system have been given
attention.

First, Thanks to all who contribute. The threads have given me alot of insight and interesting reading.

My question is as I slowly rework this beautiful old motor (starting at top and working down) I am wondering
if I should seal/block off the lower fuel pump attachment port. I included a picture because I wasnt sure how
to ask the question.

Im concerned that it would cycle air and should be blocked off. When I did the compression check it didnt
dawn on me at the time to see if there was a vacume at that location.

Planning to primer/paint the interior while parts are off rather than work to get it running and then go for
the facelift. (picked up on that suggestion in the forum as well)

Any help/experience is appreciated

Re: 1962 merc 450s fuel pump question

Those ports (two I see) are for the fuel pump to take exhaust pressure which pulsates the diaphram that in turn pumps gas out to the filter and carbs. I don,t think they would have much to do with the compression thats taken from above the intake and exhaust ports. Just my opinion. If you are going to prime the inner portions of the base and covers they must be clean and dry or the primer will not stay on. I would not suggest putting any primer or paint in the fuel pump ports pictured as if the paint sepertes it may clog the port and affect the diaphrams. Nice motor

Re: 1962 merc 450s fuel pump question

When Mercury first designed the 4-cylinder models, they felt they would need the two fuel pumps to maintain fuel volume. In practice, the only 4-cylinder Mercs that came with two fuel pumps were the Mark 30s due to their diminished crankcase volume. The second cast-in base on your crankcase is non-functioning and has not been drilled through to the crankcase so there is no need to cover it up.

Re: 1962 merc 450s fuel pump question

Thanks very much for the input and insight.