9n engine oil pump front main assembly

WRT the idea of a "self-centering" pump housing/bearing cap I'm even more confused. ISTR there's quite a bit of side clearance in the mounting stud holes in an N engine and there's no locating boss for the caps so lateral alignment is no biggy new or used. But if the original or replacement bore is a little low or high (wrt crankshaft centerline) that's not going to self-correct. The two halves are not perfect semi-circles.

I have no idea what the original manufacturing tolerances were on that operation but even a couple thou out's going to be unacceptable. OTOH if the original bore centerlines were held to less than .001 vertically any pump housing or cap would self-center.

TOH

I have rebuilt more of these engines, as well as flathead V-8's, small block Chevies, and other engines than I care to think about, yet, seldom, if ever, have I had an oil pressure "issue" with and engine I've rebuilt.

Yet, there are posts on here all the time about low oil pressure in a "rebuilt" engine.

A little attention to detail, and not "cutting corners" to save a few bucks on a already costly rebuild will save being disappointed with the results of the OH, having to to it over again, or even losing the engine to a "thrown rod" or a spun bearing.

What you can usually "get by with" if you are OH'ing the engine yourself, and are willing to live with the results is not the same as doing it correctly, or especially, doing a professional job for someone else!

I'm in total agreement with all you said and heartily endorse your suggestion to do it right the first time. But I fail to see how that relates to my original post.

Even in a low performance engine the bore in the bearing caps HAS to be concentric with the other half of the bore in the block. That's usually accomplished by bolting the caps to the web and line boring the assembly. Now you have non-interchangeable matched sets because the boring operation is usually off center (up/down/right/left) slightly. Reverse or replace a cap and you're going to bind the crank journal when you tighten the cap down - the resulting holes won't be round when the mismatched halfs are joined. Since bearing clearances are roughly .002 there's little room for error.

In an N engine were the caps "float" around the main bearing studs/bolts there's probably enough lateral clearance to adjust for centerline error side-to side. But that cannot adjust for vertical error in boring. So how can you make a self-aligning pump body (AKA cap)?

TOH

Where in the HEdouble hockey sticks have you been!

Zane