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Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: 63ConDan ()
Date: January 26, 2015 05:57PM

I have learned today that the new standard bearing have excessive clearance. so the proposed solution is to buy .010 oversized bearings and regrind the crank to match.

Two things, prior to pulling that trigger and absorb the lost time and expenses with this process are there another options or other tests to run to confirm this is the proper path?

And if not will the new standard size bearing be usable and have a value and they were installed and just measure with plastigaged?

thank you

Dan Central MN

1963 vert with '65 110 PG, 1963 Spyder vert 150 turbo,1966 Sport Coupe 140 3spd, 2002 TA WS6 Vert




Edited 1 time(s). Last edit at 01/26/2015 05:58PM by 63ConDan.

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: davemotohead ()
Date: January 26, 2015 06:00PM

Did you mic the crank first to see if standard bearings will work before ordering? If the bearings are ok I am sure someone will buy them if you do not need them.



Email me at: Dave Motohead

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Rust Free Lancaster Ca

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: cnicol ()
Date: January 26, 2015 06:04PM

Your status bearing set will still be usable and retains some value. If your crankshaft's journals are round and smooth within specs, one option is to locate a set of. 001" or. 002" undersize bearings.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe project
65 White 4-dr 110/AC/PG (parts)
66 Sprint Corsa convt - First car! Re-purchased 43 years later

+18 Tons of parts

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: 63ConDan ()
Date: January 26, 2015 06:14PM

It was purchased as a project with everything apart and in boxes including many new old stock parts from 1969 including new bearing main and rod, new cam, new pistons and rings, gaskets, springs and so on.

I am expecting some challenges just want to proceed correctly and not add cost when not may be needed.

Dan Central MN

1963 vert with '65 110 PG, 1963 Spyder vert 150 turbo,1966 Sport Coupe 140 3spd, 2002 TA WS6 Vert

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: davemotohead ()
Date: January 26, 2015 06:16PM

what were the plastigauge readings?



Email me at: Dave Motohead

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: 63ConDan ()
Date: January 26, 2015 07:00PM

good question Dave, I will ask for those. and post once I have.

Thank you

Dan Central MN

1963 vert with '65 110 PG, 1963 Spyder vert 150 turbo,1966 Sport Coupe 140 3spd, 2002 TA WS6 Vert

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: jjohnsonjo ()
Date: January 27, 2015 05:22AM

How much under, Clarks still has .002 Clevite at a reduced price.

[www.corvair.com]

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

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: jjohnsonjo ()
Date: January 27, 2015 06:52AM

If its a true 140, it should be a factory nitided crank. It is not unusual for these to be .001 or .002 under from new factory build. What does the crank mic? Does it have a "&" stamped on the flywheel end?

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

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: red monza ()
Date: January 27, 2015 07:49AM

I think it is customary for the machine shop to stamp the crank as to any change in size....there is usually two markings...one is for the main surface and the other one is for the rod surface...my 49 283 was a 10/10 turn and done down in Charlotte as I had some other work done to the crank.

Most of the engines I have built were .002 clearance for the bearings...both main and rod bearings...this 283 I failed to tell the machine shop I wanted .002 and it came in at .001 when I plastigaged it...I prefer .002....001 makes the engine a little tight and gas mileage and spin and overheating not ideal for me...the less friction...the better to a point of course.

The machinist orders the bearings after the correct crank size is established or appears to be what it will clean up at.

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: jjohnsonjo ()
Date: January 27, 2015 08:59AM

If you set Corvair mains at .001 when cold they will be at least .002 when at operating temp.

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

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: Wagon Master ()
Date: January 27, 2015 09:09AM

J.O. Since you didn't include them I will ask, will you see this same increase in clearance on the rod bearings Hot vs. Cold?

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

Been aircooled since 1973
Northwest Ohio

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: davemotohead ()
Date: January 27, 2015 09:42AM

I have never had a Machine shop stamp the bearing journal sizes on a crank nor would I want them to, Every crank I have ever had polished or Turned came with a Tag,Not a stamping.



Email me at: Dave Motohead

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: 66vairman ()
Date: January 27, 2015 09:47AM

Over the years I've had four nitrided crankshafts polished and they all mic'd with specification (by the machine shop and I double check with my tools). From my limited experience and from talking with others a nitrided crankshaft wears little unless it's been abused.

Regarding the plastigauge measurement, you said "I will ask for those. and post once I have." I'm going to guess the machine shop, or mechanic did the plastigauge.

I've had machine shops quote me clearances that don't agree with the Corvair specifications in the manual.

I'd suggest getting the plastigauge numbers and check them against the shop manual specifications. If possible repeat the plastiguage process yourself.

I'm not saying you don't have a problem, it's just nice to double check things before spending more money.

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: 63ConDan ()
Date: January 27, 2015 10:06AM

I will get the measurements, but was told it was plasigaged and found too much clearance and the measured with a crank micrometer and a bore gage to confirm, but if they are only .002 over I should be better off with a .002 under bearings and no regrind for the crank.

Dan Central MN

1963 vert with '65 110 PG, 1963 Spyder vert 150 turbo,1966 Sport Coupe 140 3spd, 2002 TA WS6 Vert

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: Wagon Master ()
Date: January 27, 2015 10:24AM

ONLY if the crank wore a perfect .002 under across the journal surface with little or no taper.
Hard to believe but it could happen. Taper too has a tolerance listed in the shop manual and it should have already been checked for.
You need to get clarification from the machine shop, did the crank measure,
1. .002 clearance, which they felt was at the top of the acceptable range? At which point a set of .001 under bearing will tighten the clearance to spec. as long as taper is minimal.
2. Crank measured .002 over including clearance (.004 total). Then .002 under bearings would bring you back to the top of spec. Again with minimal tape.

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

Been aircooled since 1973
Northwest Ohio

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: jjohnsonjo ()
Date: January 27, 2015 12:11PM

>>J.O. Since you didn't include them I will ask, will you see this same increase in clearance on the rod bearings Hot vs. Cold?<<


No; not from everything I have read, its aluminum crankcase halves expanding at a faster rate the iron crankshaft.

I never measured this myself since it happens at 200 degrees. I will say this: I am now building an engine and the crank seemed a little tighter to turn by hand than I remember. This was after malleting and and several re torques. It was below 60 in my garage. Remembering this I pointed my quartz heater at it and got the case and crank into the 120+ range, I could spin the crank with one finger.

My nitrided crank has been .002 since new. Also, the #1 rod is .001. No taper, no measurable wear at 130K. I wrote this down for all the journals at 70K and the are still the same today. Thats with a turbo that doesn't get babied.

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

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: jimmyo ()
Date: January 27, 2015 12:47PM

Things like this happen, I started work on a 140 recently and discovered the bearings I had in my stash were not correct. I have two cranks, one has been machined down .020 and with very low miles and looks great. The other is decent but there's some variences in the journals. I have a set of standard and a set of.010. After I plastigauged the "std" crank (with the std bearings), I decided to buy a set of .020 bearings, and use the better .020 crank. The runout on the std crank was at the limit, so I rather spend the money now. I can put the bearing back on the shelf. 99.9% of the parts I have, I got from buying parts stashes. My build budget is pretty much zero, but I'm not comfortible with "good enough". And I will plastigauged the .020 crank, with the .020 bearings to be sure it's right.

Jim O'Connor
45 miles north of The Bronx, N.Y.
1962 Greenbrier 110 4spd
1964 Monza Convertible 110 PG
"Wherever you go....There you are"

 photo 045ef0c8-2087-4eac-8a5d-9aa0d575d5e0_zps9946d378.jpg
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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: vairmech ()
Date: January 27, 2015 12:54PM

I think before anyone can give any advice we need to know what the crank journal measurements are. All 4 mains and one or two rods.

Once those numbers are posted you have your answer. Anything before is just conjecture.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: jjohnsonjo ()
Date: January 27, 2015 01:03PM

Agree 100% with Ken, what are the measurements?

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

Image and video hosting by TinyPic

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Re: Problem with 1966 CHEVROLET CORVAIR 140 Engine rebuild: Crankshaft Main Bearings
Posted by: Vairismo ()
Date: January 27, 2015 01:09PM

Maybe the engine guy is just trying to sell you on a job for him, wouldn't hurt to seek a second opinion on the situation.

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