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The ‘net is full of ways to do it. What crosby suggested is probably the simplest. Next simplest is tap into the existing bypass cover for a hose fitting to drive the pump. I’m posting a picture to illustrate the concept, although this is not a Big Twin. This guy used a Briggs & Stratton fuel pump, available everywhere & cheap..
see picture on a different motor… same basic solution to get a pulse feed for the pump
but…. if you mounted a pump on a 1/4 center drilled 1/16inch aluminum plate OVER a 1/4 inch drilled bypass cover
you would feed the pulses directly into the pump from the rear and save a hose . then just plug the air pressure feed nippleoffset set the pump and bolt it on the plate from the rear . The aluminum plate can be patterned with the bypass cove plus about 1/2 inch over reach. This allows to mount the plate on the bypass cover while allowing the left side bolt to be installed OUTSIDE the bypass cover zone leaving one bolt inside .
before mounting the plate flatten the cover plate over 100 grit paper on a flat surface till all shiny..and flat. make up a paer gasket or apply some gasket sealant between the plate and bypass cover (bolt up your pump first !! ) bypass cover original bolts may now be short a bit so install longer ones . I use star washers to lock them down
up to you know 🙂
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Thanks Mr. Crosbyman for all your help and patience on this. I understand the plan to mount the pump directly over the port. The raised edges of the port cover would be gasket surfaces once machined flat. These are kind of thin (3/16 in) and any leakage here could be disastrous. I think I would have less to worry about if I begin by placing the hose connector in the existing boss and finding a spot for the pump.
I will make one more try to post a photo but not much luck with this computer.
it is up to you but if you just shiny up the surface of the lower bypass cover for ex.: on 100 grit paper and make a patterned cover plate of 1/16 aluminum you could mount the pump on the cover plate and drill a 1/4 inch hole in the best quadrant aligned to the pump’s rear center pulse port
Me I would try to use a lower quadrant corner edge allowing any accumulated fuel/oil pushed in the void behind the pump to simply drain back into the crankcase . This will prevent any puddle of fuel staying in the bypass cover. pick a quadrant and drill at a slight down angle. remove the bypass to drill it !!!
other quadrants can be filled with JB to eliminate any chance of the “extra” volume affecting the pump operation or crankcase pressure specs
seal the aluminum plate /pump assembly over the drilled bypass cover with either a paper gasket cut to shape or gasket sealant
the crankcase does not generate high piston like PSI’s since on the downstroke it pushes new fuel in the cyl and expels burnt fuel at the same time. On the upstroke it sucks fuel from the carb.
both these actions will pulse your new pump directly or via a brass nipple tapped in..OK I have never done a big twin so it is all up to you Option#1….you drill, plate and mount a 2 nipple pump or Option #2 you mount a 3 nipple B&S pump anywhere you can and hook up your pulse line to a brass nipple tapped into a bypass port as per the pictures above..
this latter option may be your best if you are worried with option 1 (drilled and plated bypass cover ).
up to you now.
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