Engine and Transmission Tech

tips, technology, tools and techniques related to vehicle driveline components

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BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Newbie trying to fire it up
Posted by: BlownMGB-V8
Date: February 25, 2009 10:10AM

I bet that was a relief.
Look for any signs of scoring in the bearing, or any indication that the bearing could have been pounded out. Check whether it is a snug fit in the rod, or has been sprung and wants to just fall out. Chances are good the builder just managed to somehow miss applying final torque to that cap. You should definitely check torque on all of the rods, and maybe the mains also. Congratulations, and hopefully that's the last of your worries.

Jim


MGBV8
Carl Floyd
Kingsport, TN
(4511 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

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Re: Newbie trying to fire it up
Posted by: MGBV8
Date: February 27, 2009 05:21PM

No lock washers!

Check that bearing shell real well. What year is your engine? Is it a Rover 3.5?


relative4
Billy Andrews
Denver, CO
(55 posts)

Registered:
11/25/2008 02:28PM

Main British Car:
'80 MGB Rover 3.5

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Re: Newbie trying to fire it up
Posted by: relative4
Date: February 27, 2009 05:46PM

It's an '80 3.5. The bearing looks OK....


relative4
Billy Andrews
Denver, CO
(55 posts)

Registered:
11/25/2008 02:28PM

Main British Car:
'80 MGB Rover 3.5

authors avatar
Re: Newbie trying to fire it up
Posted by: relative4
Date: March 05, 2009 11:51AM

Got it all back together and running. The clanking is gone, though to my uneducated and possibly paranoid ear the engine sounds a tad less healthy than before the bearing cap loosened. Thanks for all your support!

Next question - what are the procedure/guidelines for adjusting the mixture and idle?


Moderator
Curtis Jacobson
Portland Oregon
(4576 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

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Re: Newbie trying to fire it up
Posted by: Moderator
Date: March 05, 2009 12:20PM



relative4
Billy Andrews
Denver, CO
(55 posts)

Registered:
11/25/2008 02:28PM

Main British Car:
'80 MGB Rover 3.5

authors avatar
Re: Newbie trying to fire it up
Posted by: relative4
Date: March 05, 2009 06:29PM

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?


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Newbie trying to fire it up
Posted by: BlownMGB-V8
Date: March 08, 2009 12:10AM

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



MGBV8
Carl Floyd
Kingsport, TN
(4511 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Newbie trying to fire it up
Posted by: MGBV8
Date: March 08, 2009 12:26AM

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


NixVegaGT
Nicolas Wiederhold
Minneapolis, MN
(659 posts)

Registered:
10/16/2007 05:30AM

Main British Car:
'73 Vega GT 4.9L Rover/Buick Stroker

authors avatar
Re: Newbie trying to fire it up
Posted by: NixVegaGT
Date: March 09, 2009 03:08PM

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?


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Newbie trying to fire it up
Posted by: BlownMGB-V8
Date: March 10, 2009 12:22AM

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


relative4
Billy Andrews
Denver, CO
(55 posts)

Registered:
11/25/2008 02:28PM

Main British Car:
'80 MGB Rover 3.5

authors avatar
Re: Newbie trying to fire it up
Posted by: relative4
Date: March 10, 2009 06:22PM

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.


Moderator
Curtis Jacobson
Portland Oregon
(4576 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: Newbie trying to fire it up
Posted by: Moderator
Date: March 10, 2009 07:03PM

Quote:
How 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.
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