Forum

[Dean]

purchased the higher output feed and return pumps from our host. the return pump works fine in the disc, but the feed pump wont go all the way in the disc and therefor the disc wont fit in the housing properly. don't want to force it in and don't want to take a chance on damaging the worm drive as the result. would like to remedy the situation as opposed to sending the part back, as that will delay the final step in this rebuild and keep me off the road. takes a couple weeks to get things to and from, as I live in Nevada.

[PeteF]

Do you have a particular reason for fitting high output pumps? The engine in standard trim doesn't need them. Anyway, there's a tech note here about it. I seem to remember you need to do a bit of gentle machining to make some of them fit.

[Alan R]

Hi guys------- DEAN, the scavenge(or "return")unit, situated at the front of the timing cover, has a greater pumping capacity than the feed (or "supply")one has....Therefore the scavenge piston is of greater diameter than the supply one, given that the stroke is the same.....BUT, they both fit into their respective bodies in the same manner.....SO, keeping the two types of pumps separate from one another, dismantle the return pump and visually compare the two assemblies to identify any differences that may exist, especially the depth that each hole is drilled to (they should be the same)--I suspect it might just be a case of cleaning out the hole that the piston fits into.....or some swarf somewhere ??

[Dean]

reason for fitting higher output pumps is that I am doing a rebuild and thought it couldn't hurt. hoped it may run a bit cooler, as I live in the desert southwest. how would I machine the discs without comprimising the seal with the plunger - if you have a method I would appreciate details, as I'm kind of new to all this.

[Dean]

it appears that the hole wasn't drilled deep enough in the disc for the plunger to go all the way in.

[Leon Novello]

There is a technical note somewhere that says they have to be gently eased in with valve grinding paste. Personally, I don`t change anything until it`s brokem.

[Jack]

I believe the HO pumps go together with the roller big end kits or hi output motors.

[Dean]

will try lapping compound - thanks for the tip

[Norm]

Dean,
Are you sure it is the feed pump causing problems it usually is the scavenge pump piston that binds up on the housing of the timing cover. You usually have to file a bit off the housing to allow the piston to clear