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Crank Reassembly - It's REALLY tight

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Crank Reassembly - It's REALLY tight
#1
RobertsMGB Avatar
RobertsMGB Gold Member Bob RobertsMGB
Berne, NY, USA   USA
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1954 MG TF
1963 MG MGB MkI
1969 MG MGB GT
1970 MG MGB
Crank was turned to .010 and have .010 bearings. Assembled and plastigaged each journal with 70 lbs of torque and they all measured about .020. If anything, a tad on the high side of .020. Disassembled and cleaned everything up, assembly lube on everything and torqued back down. Now it's difficult to turn without a little leverage. Seems much too tight but I don't see what the problem could be. Any suggestions from you engine experts??


Bob Scardamalia
Albany, NY
'63 MGB #4754
'69 MGB-GT #180279
'54 MG-TF #2259
'54 MGTF #2259

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Re: Crank Reassembly - It's REALLY tight
#2
dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
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Bob,

I suspect you mean 0.002 and not 0.020...

Are pistons and rings in?

Dick


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Re: Crank Reassembly - It's REALLY tight
#3
dbandel Avatar
dbandel Silver Member David Bandel
Glenwood, MD, USA   USA
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1967 MG MGB GT
1974 MG MGB
Bob,

I'll assume this is a bare crank laying in the block, no connecting rods, pistons and spark plugs installed and hence compression working against rotation? Sometimes they can feel very tight (and they should be fairly snug) but are you sure you used the correct plasti-gauge and measured correctly? I believe the correct clearance is somewhere in the .0015"-.0020" range, not .020". If it is, that's way too "loose" and you won't be able to maintain any oil pressure. Not knowing what other work you had done to the block or crank I really can't help ID the issue. I would redo checking the clearances again. If it is so tight you have trouble turning it with a breaker bar (and you weigh more than 85 lbs soaking wet) you may want to get a second "first hand" opinion locally.

-David

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Re: Crank Reassembly - It's REALLY tight
#4
dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
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At 70 ft-lbs you must be referring to the main bearings, with no rods installed. With lube on the crankshaft it should turn smoothly and evenly by hand...

Suggest you loosen them all and tighten at one journal at a time and see if the crank turns smoothly with each journal. Check to make sure main caps 2, 3, and 4 are all correctly oriented with "Front" toward the front, and make sure that caps 2 and 4 are on the appropriate journal. A reminder that, on our engines, all rod and main caps are installed tang-to-tang...

Dick


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Re: Crank Reassembly - It's REALLY tight
#5
RobertsMGB Avatar
RobertsMGB Gold Member Bob RobertsMGB
Berne, NY, USA   USA
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1954 MG TF
1963 MG MGB MkI
1969 MG MGB GT
1970 MG MGB
Correction on the plasti-gauge reading - yes, it's .002 on all and it's the green that should measure between .001-.003 Bare crank no pistons or anything else in. The assembly lube I used is the sticky stuff. Would that be the difference? Wondering if I should clean it all off and use a different lube. I can turn it using a screwdriver as a lever on the flywheel end but it's difficult to move without any leverage.


Bob Scardamalia
Albany, NY
'63 MGB #4754
'69 MGB-GT #180279
'54 MG-TF #2259
'54 MGTF #2259



Edited 1 time(s). Last edit at 2014-04-16 03:38 PM by RobertsMGB.

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Re: Crank Reassembly - It's REALLY tight
#6
Rod H. Avatar
Rod H.
Amity, OR, USA   USA
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1964 MG MGB
1968 MG MGB GT
What's the crank endplay? Could be the thrusts are too tight or the cap needs to be centered.


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Re: Crank Reassembly - It's REALLY tight
#7
dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
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Bob,

It should turn smooth as butter by hand. With such a critical assembly you really should take it all apart and re-check everything and re-tighten one journal at a time... Try assembling with just engine oil...

Dick




In reply to # 2663588 by RobertsMGB Correction on the plasti-gauge reading - yes, it's .002 on all and it's the green that should measure between .001-.003 Bare crank no pistons or anything else in. The assembly lube I used is the sticky stuff. Would that be the difference? Wondering if I should clean it all off and use a different lube. I can turn it using a screwdriver as a lever on the flywheel end but it's difficult to move without any leverage.


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(Often wrong, but always certain)

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Re: Crank Reassembly - It's REALLY tight
#8
maggelie Avatar
maggelie Arthur Nichols
Severn, MD, USA   USA
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1974 MG MGB MkII "Magglie"
check the thrust washers. mine were too tight when we put it together the first time.

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Re: Crank Reassembly - It's REALLY tight
#9
oleanderjoe Avatar
oleanderjoe Platinum AdvertiserAdvertiser Joseph Baba
Fresno, CA, USA   USA
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1962 Triumph Spitfire 4 (MkI) "SPITTY"
BOB: Are all the main bearing caps installed and torqued??, if not sometimes the crank will feel like its to tight. Also carefully measure the crank end thrust, were they replaced??, standard or oversize. ??
Joe


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Re: Crank Reassembly - It's REALLY tight
#10
fast-MG.com Avatar
fast-MG.com Dave Headley
Cortez, 4 corners, Colorado, USA   USA
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Many of the new thrust washers that I have seen lately, while measuring the correct thickness, are slightly warped and act thicker when installed. Best to use good old ones.

Also if assembly lube is too thick you will feel more drag.

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Re: Crank Reassembly - It's REALLY tight
#11
LannM Avatar
LannM Platinum Member Lann Mauck
Verdigris, OK, USA   USA
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1958 MG Magnette ZB Varitone "The Queen"
1963 MG MGB
1967 MG MGB GT
Was the block line bored?

Each journal can be correct but if they are not all on the same center line the crank will bind up as you tighten the caps.

Lann


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Re: Crank Reassembly - It's REALLY tight
#12
RobertsMGB Avatar
RobertsMGB Gold Member Bob RobertsMGB
Berne, NY, USA   USA
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1954 MG TF
1963 MG MGB MkI
1969 MG MGB GT
1970 MG MGB
I'm using the original thrust washers so wouldn't expect them to be the problem. There's really no endplay in the crank. Have all of the mains torqued down. Will take it all apart and start over


Bob Scardamalia
Albany, NY
'63 MGB #4754
'69 MGB-GT #180279
'54 MG-TF #2259
'54 MGTF #2259

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Re: Crank Reassembly - It's REALLY tight
#13
mikemgb74 Avatar
mikemgb74 Michael Trumbower
New Haven, IN, USA   USA
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Could be a warped block...mine was. Had to get a line bore on the main journals. Then, crank turned like butter smooth.

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Re: Crank Reassembly - It's REALLY tight
#14
Denis Avatar
Denis Denis Hill
Bearii, Nth Victoria, Australia   AUS
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1968 MG MGB MkII
1973 MG MGB V8 Conversion
Bob before you dissemble it loosen the caps,until just slight tension, remove the flywheel and with a soft dead blow hammer or the like drive the crank in both directions to align the main caps then check it again.. {if you haven't done this already}. denis


68 B roadster, Daffodil yellow, supercharger, Burgess SC head, SC cam, Mikuni HSR 48 carburetor and engine built for supercharging.

73 BGT V8 conversion starting with a bare shell. Built the engine "3.9L Rover" early in 2016 with high comp pistons and a few other nice bits, plus a T5 ford trans. Started on the body late 2016 and complete late 2017, Did all the work myself, mechanical, body. paint etc.
Finished and going well, great to drive and quick. Now has a nice 3.23 LSD.

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Re: Crank Reassembly - It's REALLY tight
#15
Rick Fawthrop Avatar
Rick Fawthrop Gold Member Richard Fawthrop
Langley, WA, USA   USA
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1960 Austin-Healey Bugeye Sprite
1974 MG MGB
1994 Mazda Miata
What kind of tools are you working with here? And which engine? A three main or a five main?
I would check the crank for straightness with some v blocks and a dial indicator. Torque the main caps with no bearings and check the size and straightness of the main line.
I would think that you are going to pack up the block and crank and head to the machine shop. I would get the line bore done and deck the block.

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