Re: [AMC-list] failed 195.6 OHV oil pump....

[Frank Swygert <farna@xxxxxxx>]

Tom, you're way over thinking all this again! Back up a bit...

All gear drive type pumps run pretty much the same. One gear is driven and the other "floats" on a shaft... with the exception of the "pancake" type, they have a small driven gear running inside a large floating driven gear... so in that respect they are similar too.

The angle of the pump makes no difference -- the 232/4.0L pump gears are VERTICAL and run against the cover more than the 196 gears do. Most V-8 oil pump gears are vertical also. The AMC V-8 oil pump goes out the bottom at the same angle as the distributor -- much steeper angle than the 196 but not vertical like the modern AMC six. All the Nash engineers did was consider how much clearance they could/wanted to machine to then made the gears long enough to deliver enough volume at those clearances. The gears on the 196 oil pump are a bit longer than those on the more modern six, but tolerances are a bit closer on the newer one too. At most the material the gears are made out of may be different and expand more, but in a nutshell you just "improved" the pump too much! Loosen it back up with a thicker gasket. You'll know immediately if that works by the oil pressure gauge.

-------------------------
On Fri, Jul 2, 2010 at 5:26 PM,<wrambler242@xxxxxxxxxxx>  wrote:
>  I'd guess that the cover being steel compared to cast means next to nothing.
>  ? ?Probably 90% plus of modern engines have cast body w/steel covers.

Tom replied:

Yeah, but not Nash's design! The passive gear just floats around in the 
cavity on an axle. I can't recall what a 232 or later v8 pump looks 
like. Since the pump runs at a funny angle, and at rest the gear sits

touching the cover, it really needs to be PERFECTLY flat and
perpendicular to the gear. The metal-to-metal contact on my mess is
not evenly spread around the cover, but biased to one side; I wonder
if my milling of the pump body left it not perfectly perpendicular to
the gear ends. This job really was outside the precision of my
mill+experience.



--
Frank Swygert
Publisher, "American Motors Cars"
Magazine (AMC)
For all AMC enthusiasts
http://www.amc-mag.com
(free download available!)

_______________________________________________
AMC-list mailing list
AMC-list@xxxxxxxxxxxx
http://list.amc-list.com/listinfo.cgi/amc-list-amc-list.com