BritishV8 Forum

I have the manual, but the first thing it says to do is to set the air screw to the desired speed.  I don't know what speed that is.  I tried around 850 RPM, and I was able to follow the rest of the procedure more or less, but I'm still not confident.  Also, at those speeds, the oil pressure is REALLY low, sometimes under 10 PSI.  Is that normal?

You should have 10 psi per 1000 rpm, so yes, 10 psi at idle is considered acceptable. You would naturally like to see a bit more, but it should be safe at that pressure.

Jim

Well, 10 PSI with hot oil low end of okay. 10 PSI with cold oil, not good.

OK so there are a number of problems with the "Rebuild" we've seen so far. My guess is that since the journal caps weren't likely torqued down properly the likelihood that the cam bearings have been changed is pretty low. They are not easy to do so I'm feeling like they didn't get done.

Old cam bearings will lead to a low pressure condition right away. One of the biggest problems with the Rover/Buick is over oiling of the cam bearings, among other things like the rocker shafts. The holes for the cam are really big and need to restrict flow more than other engines. As the cam bearings wear the tolerance widens and a lot more oil slips past the bearings. My guess is this is why the pressure is low.

All that said. I hope it isn't. Anybody swapped cam bearings in an assembled engine?

Oiling is the Achilles heel of the Buick engines, at least post- Nail Head. This problem is addressed in several ways, but particularly by using tight bearing clearances at the crank (.0015" and less is the norm), making certain no unnecessary losses exist at the lifters, and by enlarging the oil pickup passages, radiusing the corners of the oil passages, particularly in the timing cover, blending in the oil passages in the oil pump housing, and using the V6's 5/8" oil pickup tube. Cam bearings which are worn or improperly installed (such as by inaccurate hand scraping) also cause losses.

In your case, with the engine assembled, the pickup tube, pump lower housing modifications, and possibly timing cover mods are about all that can be reasonably done without a full disassembly. Personally, I would try a thicker grade of oil. If you are using 10w40 try a straight 40 or even 50 weight such as the Valvoline racing oils. That will probably get your oil pressure up into the acceptable range. I know, it's a band-aid, but it does work and unless you drive it in really cold weather it shouldn't cause problems.

Jim

Thanks for the heads up, guys.  The cam was replaced, so maybe I got lucky on those bearings, but I won't bet on it.  

I'm still getting a noticeable amount of noise from #3.  I can't tell bearing noise from piston slap from a hole in the ground, but I think I should replace the connecting rod bearing to start off with.  Where's a good source for individual bearings?  VB only sells full sets.  How do I determine what thickness to get?

When I do that, I can replace the 10W40 with straight 40 as you suggest.  I'm in Denver but probably won't drive it on cold days.

QuoteHow do I determine what thickness to get?

When you remove the old bearing, you'll find the size (e.g. "010" for ten thousandths under) is marked on the outside of the old bearing's shell. (It will be marked on both halves.) Some machinists also stamp measurements on a crank counterweight when they turn the crank (e.g. "M 0.010 R 0.010"). If all else fails, I suppose you could get out your calipers and measure. When you put it back together, it would probably be good to use some "plastigage" to measure/verify clearances.