The Ford Barn

tubman · 11-07-2017, 04:24 PM

Well, I am real happy with the 258" engine I just completed, except for one thing. I opted to save $100 and went with a Speedway oil pump. While the pump provides adequate pressure, the new engine has substantially less oil pressure than the used engine (with used pump) I installed in my '51 this summer. That engine idles hot at 25 psi and runs (over 1500 rpm) hot at 55 psi. The rebuilt idles hot at 10 psi and runs hot at 40 psi. Since everything else is fine with the engine, I suspect the oil pump is not up to snuff.

I dug through my stash and found two original 8BA pumps that look to be serviceable. I checked the side clearance between the gears and the housing and one is .0015", while the other is .003". Since factory specifications call for a maximum of .005", I figure I am in good shape here. I used "Plasti-gage" to check the clearance between the ends of the gears and the bottom plate. The news here was not so good. One has .003" over the idler gear and .006" over the driven gear; the other has .005" over the idler gear and .006" over the driven gear. Since factory specs show a maximum clearance of .006," I suspect they may be usable as is. I am going to send them to "Flatjack" who graciously has offered to test them for me on a setup he has.

I am wondering if I should try to bring the end clearances down a bit before I send them. I have a "surface plate" (a 2" thick slab of perfectly flat granite) that I could use for this. I have used it before to flatten warped carburetor bodies by putting wet-or-dry sandpaper on it and rubbing the pieces back and forth. Even though the pump body is cast iron, I feel I should be able to remove a couple of thousandths quite easily. Is this feasible (or even worth the effort?).

11-07-2017, 04:24 PM	#1
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,320	Oil pump "rebuilding" Well, I am real happy with the 258" engine I just completed, except for one thing. I opted to save $100 and went with a Speedway oil pump. While the pump provides adequate pressure, the new engine has substantially less oil pressure than the used engine (with used pump) I installed in my '51 this summer. That engine idles hot at 25 psi and runs (over 1500 rpm) hot at 55 psi. The rebuilt idles hot at 10 psi and runs hot at 40 psi. Since everything else is fine with the engine, I suspect the oil pump is not up to snuff. I dug through my stash and found two original 8BA pumps that look to be serviceable. I checked the side clearance between the gears and the housing and one is .0015", while the other is .003". Since factory specifications call for a maximum of .005", I figure I am in good shape here. I used "Plasti-gage" to check the clearance between the ends of the gears and the bottom plate. The news here was not so good. One has .003" over the idler gear and .006" over the driven gear; the other has .005" over the idler gear and .006" over the driven gear. Since factory specs show a maximum clearance of .006," I suspect they may be usable as is. I am going to send them to "Flatjack" who graciously has offered to test them for me on a setup he has. I am wondering if I should try to bring the end clearances down a bit before I send them. I have a "surface plate" (a 2" thick slab of perfectly flat granite) that I could use for this. I have used it before to flatten warped carburetor bodies by putting wet-or-dry sandpaper on it and rubbing the pieces back and forth. Even though the pump body is cast iron, I feel I should be able to remove a couple of thousandths quite easily. Is this feasible (or even worth the effort?).