Frank DuVal Wrote:
-------------------------------------------------------
> Ken, you are saying not to bolt and torque the
> block halves, just set the crank in place and
> apply some hand pressure right? And do it for both
> block halves?
>>>>>>>>>>>>>>>>>>>>>>>>>

Yes.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Wgator... he's tried two cranks...

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MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
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Two items to ponder,
1. You do realize the #4 unflanged main bearing on the flywheel end is not the same dimensionally as the middle two correct? #4 insert, usually marked with dye on the edge is .0015 thicker on the top and .0015 thinner on the bottom. Having the effect of lowering the centerline of the bearing .0015
2. The #2 and #3 main bearing inserts I have in stock have a shell thickness of .0948
Measure your middle two and see if these would gain you any clearance.

'64 Monza Coupe 140 4 speed
'61 700 Lakewood 95 4 speed
'69 Monza Convert. 140 Auto.

Been aircooled since 1973
Northwest Ohio

Wagon Master,

1. Yes, I'm positive that the correct bearings are in the correct order. The #4 bearing is marked in brown and is marked differently than #2 and #3.

2. Thank you for the the bearing measurements!


All,

I'll be in the shop today doing some more inspection work. But it's pretty clear that the case is the fault. This is based on measurements I'm taking from the case bores compared to measurements given to me by a builder with correct measurements. I'll do some more measuring and plastigauge-ing. But it appears that the middle two bores will need a careful, light honing at a machine shop. I'll report back.

Cheers.

At this point I would torque it to specs with no bearings, crank or cam. Then use a bore mic ( you or machine shop) to check the saddle diameter. If they are OK then somehow the case is not straight.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Hi everyone.

I fired up my 110yo kerosene burner and went to work. Some notes:

1. Plastigauge time! Basically it looks perfect. All of the bores measure at .002", except for bore #3 which was just over sitting between .0015" and .002". But it looked perfect.

Note that the wear on bearings is not where the Plastigauge sits. If the engine half is sitting with the bores facing up, then the wear is about 45 degrees. I have pics and can upload them shortly.

**** THE MOST IMPORTANT note here is that the bearing wear is on the right case half only. The left half only shows tiny marks where I've been measuring.

2. I re-measured the crankshaft and it's perfect. Each main journal measures .098", technically varying between .0984-.0988.". Very nice.

3. With the main bearings installed, case halves bolted and torqued, I'm measuring the following (vertical in parenthesis):
Bore #1 - .097-.098 (.990)
Bore #2 - .098 (.098)
Bore #3 - .098 (.098)
Bore #4 - .098 (.098)

There is a variance as much as .0005 between horizontal and vertical measurements.

4. WITHOUT main bearings installed, here are the bore measurements. These get weird. If I measure the bore on the side closest to the rear of the cae, it can vary as much as a thousandth on the same bore but measured on the side closest to the front of the case.

Bore #1 - .287, .288 (vertical .289)
Bore #2 - .287, .288 (vertical .289)
Bore #3 - .288, .289 (vertical .289)
Bore #4 - .288, .288 (vertical .289)

5. Standard size bearings measuring at the very edge to get the flattest spot to measure. These are all over the place. I thought these would have little variance but the thickness varies between one side of the bearing and the other. The service manual says bearing #4 should be .0015" thicker, but I'm not really seeing more than .001."

Bearing #1 - .094, .095
Bearing #2 - .094, .095
Bearing #3 - .094, .094
Bearing #4 - .096, .096

That's it. Still confused. Everything seems to measure perfectly - Plastigauge says .002", and my gauges+micrometer say the same thing. On page 6-54 of the service manual, it says that if I can't solve the clearance with bearings, then "it will be necessary to to regrind the crankshaft journal for use with the next undersize bearing." Oy.

Photos coming up next.

Photos:



Overview of left side case:




Wear on bearing #2:





Wear on bearing #3:





Plastigauge:

Ouch!

---

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
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You may want to try some layout dye (or Prussian Blue?) on the crankshaft journal to try and see the wear pattern/spot or flaw of some kind on the ground part of the journal itself. You seem to have checked most everything else.

Did you have ANY lubrication when you rotated the crank to get those marks?

That looks more like a bearing issue and not anything else. Is there any witness mark on the crank?

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Ken pretty much summed up my thoughts on the pictures. No way in my mind two smooth arced surfaces made those marks. You missed a burr somewhere. If those ice pick marks were made by measuring, buy or borrow a set of ball end mics to do your measuring. Also the upper stud/threaded insert in picture of bearing #2 may be sticking into the case too far. There's very little clearance for the assembled rod to swing by that area.


'64 Monza Coupe 140 4 speed
'61 700 Lakewood 95 4 speed
'69 Monza Convert. 140 Auto.

Been aircooled since 1973
Northwest Ohio

Yes, I'm using synthetic assembly lube.

Small update. I delivered both crankshafts to a machine shop today just to have them verify concentricity, have them fluxed, and a light polish. If they come up good then it verifies the case being the problem. Assuming it's the case, I'll take it from there.

Maybe I misread your data, but didn't you just determine that your block bores (without bearings installed) were tapered from front to rear? Meaning that within the same bore, you got different measurements between the front of one bore vs the rear of the same bore?
If that's the case then it could certainly contribute to squeezing the bearings against the crankshaft unevenly.

Again, sorry if I misread what you were saying. It just sounded like that was a problem.

Paul

Bob he mic'd the bores and they were OK, so are you saying the line bore is off center. I wondering about the bearing shells being bad.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Bob Helt Wrote:
-------------------------------------------------------
> I don't know about you, but based on your #2
> photo, I wouldn't use that crankcase.
> That bearing sits too far inside the web to match
> the mating bearing.
> Bob Helt


Yes,Something is odd about the bearing not extending to the mating surface.




The Corvair, Keeping Nader Notorious


Will
Northern California

jjohnsonjo Wrote:
-------------------------------------------------------
> Bob he mic'd the bores and they were OK, so are
> you saying the line bore is off center. I
> wondering about the bearing shells being bad.


I don't know exactly wha the problem is, but the edges of the shells should butt together when the case halves are joined and bolted. This shell in the #2 photo sits too far inside the case web to do that.
Bob Helt

Problem-o solved-o!

After making a few changes, I have the case halves torqued together at 55 ft/lbs and the crankshaft spins nicely.

I did three things to resolve the problem:

1. I took the crankshaft to a machine shop just to have them re-verify the health of the crankshaft and to give it a polish.

2. At the school machine shop where I'm a (old) student, we made up a jig with a length of 2" pipe to give the bores a very even hone, or rather very light polish. I looked around for a long time to find a local machine shop willing to do this, but one wanted to work on a Corvair engine. Except for one interesting high-end shop who offered to do it for $500. I spoke a long while with the manager about this and other projects and he offered me a job. Cool!

3. I swapped out the bearings with some NOS Clevite 77 half-flange bearings. I would prefer full flange of course, and my other ones were never harmed so I'll putting them it and see it causes any trouble.

But that's it. No single cause, just a few odd not-at-all straightforward issues. I'm stoked to be past this trouble, and now I can finally move to buttoning up the bottom end.

Hooray!

A big thank you to everyone who provided brain power here and privately.

All that matters is it's fixed!

---

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
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