Pulled my 68 350 out of my 68 skylark convertible. Going to do a re-ring. While it is out I was planning to do some oil mods, but I called TA to know what they recommend, and they said don't do any. I plan to run their dual groove cam bearings, but would like thoughts on if I should do anything else. Mild cam and aluminum intake are all I am running.
If you were going to do any oiling mods like the 455, it would require a bare block, and afterwards a THOROUGH cleaning. I don't think that is necessary. I would blueprint the oil pump clearances and use a booster plate. If your oil pressure was good, and you had 10 psi/1000 RPM, there is no reason to do anything else. https://www.v8buick.com/index.php?threads/oil-pump-clearances-and-oil-pressure.326597/
I don't really agree with that. At the very least I'd switch over to the V6 oil pickup and gasket, but since the pistons will be out, why not check your bearing clearances? If they are within stock specs fine, but if not, tighten those up to the .0008-.0012 range, enlarge the suction journal and do a little porting around the oil pump, set the pump gear end clearance to the minimum shy of dragging and you should do very well with it. I get 50psi at idle with 5w30 synthetic oil and will drop the viscosity further at the next oil change. Jim
I didn't have great oil pressure, but that isn't why I pulled it apart. I had marginal oil pressure at higher rpm. Front cam bearing doesn't look great, and all the bearings will be replaced. I was not intending to do any changes to the crank or rods. Are there reasons not to do the suction side mods? For reference I have an aftermarket timing cover, but not TA, I use a booster plate and an adjustable regulator
i'm against the booster for a stock 350 or there-abouts. i took mine off because of cam/dizzy gear wear. was idling at 60psi. i just shim the pump spring and it still will hit close to 100 cold. the 350 is a pretty stout engine in normal mode. running a blower is a wee bit different. lol
Actually I was able to do mine without removing the rotating assembly https://www.v8buick.com/index.php?t...oving-crank-rods-pistons.356123/#post-3049924
That's why I'm going to a lighter oil. You seek to strike a balance, with anywhere from 10 to 30psi at idle being the goal and 10psi/1000rpm upwards from there. If the engine is tight that can be done whereas if it is loose it can't. You can always bleed off excess pressure various ways, the best probably being with lighter oil and/or larger pump clearances. Lighter oil means less drag so that's my approach, and if I do happen to spin a bearing in this low mile OEM 300 I'll consider running more pump clearance in the stroker/blower motor presently under build. New engines run 0w20 oil and there's no reason older ones built right can't also. I don't think the booster plate adds any pressure, but it does give a fresh and hard wear surface for the gears. I port the plate openings because of the sharp edges. Think about how the oil must flow. Drilling the block: Use a piloted drill bit. This can be done with only the pan, pickup and timing cover removed. Use a piloted drill bit. Chips fall down. Spray and brush it out with brake/carb cleaner and wash off any that gets on the surrounding areas. I like to run a bur in from the pickup hole to dress the corner. Use a piloted drill bit. Do I need to keep saying this? 9/16" is sufficient but you can go to 5/8 if you are careful and brave. If it breaks out you can fix it with hardware store brass tubing and a good sealant. With fresh bearings if your clearances are almost within spec you might get your machinist to bring them in with a rod resize/main align hone. Or just go .010" undersized on the bearings. Make sure your machinist is comfortable with the tight clearances the new engines use and he should have no issues with holding tight Buick clearances. Jim
jim, i run regular 10-30 amsoil, not racing oil. no problems, no leaks, nothing. and i just shim the pump spring now. if i don't get scared with a 25k crazy engine and not break it, why does everybody else shiver?
Well Johnny here's the way I see it: As a starting point let's recognize that Buick in their infinite wisdom enlarged the suction galley to 5/8" in the 3800 V6. The reason is clear if you look. Atmospheric pressure is 16psi at best, and atmospheric pressure is all you ever have or ever will have pushing the oil up to the pump, because even in a perfect world the pump can never go beyond creating a perfect vacuum. Therefore, 16psi is it. That's all you got. Now with a 7/16" discharge port and 70psi max discharge pressure we don't need to actually run the numbers to see that the inlet side needs to be a little larger than the discharge side. (examine any hydraulic pump for consistency in principle) How much larger? Well we can estimate reasonably closely based on pressure available and 4 times 16 is 64 so a four to one factor would insure that the inlet flows enough to not restrict the outlet. In a round tube, double the diameter quadruples the area so by estimate a 7/8" inlet size would eliminate any chance of cavitation in the pump. Other factors are involved of course. There is oil film strength and vapor pressure that affect cavitation. The outlet is restricted so even though it is a positive displacement pump there are losses on that side and a full flow is not going to happen. But the bottom line for me is that the Buick Engineers determined that a 5/8" inlet was needed, and since it isn't practical to go any larger than that, here we are. In practice I've found 9/16" to be adequate when paired with tight bearing clearances and porting of the pump, etc. at engine speeds below 6K but beyond that you pays yer money and takes yer chances. I'm not trying to tell anyone they have to do what I say but it doesn't hurt to listen. If you have consistent good results with the stock setup I'm real happy for you but I was never so lucky. Since the extra precautions are really pretty easy when building an engine and much harder afterwards, why not? Jim
Get a large oil pickup tube. And new cam bearing in front at least. Watch so you don’t drill too far on suction side. 9/16 is as large as I would go. And got to be straight.
jim, sorry for delay reply. getting rail for car show this w/e. and my old bones are killing me because of it i think one reason buick made bigger holes was due to coming out with the indexed crank, and unquestionable crank failures, they had to do something to alleviate the problem. i really don't have a definitive answer other than we all continue to band aid the problem. some of us are lucky or good at it and some of us suck at it. but discussion of it by us talking about it hopefully will help the rookies. may they learn and come up with a better answer than we have given.
