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#2413153 - 12/04/17 02:09 PM Small block thrust bearing cap alignment
crash520 Offline
member

Registered: 10/26/13
Posts: 185
Loc: Brisbane Australia
Guys, ref 360, thrust bearing cap to block alignment. I have ARP mains studs, without bearings fitted I noticed the surfaces front and rear of the #3 bearing cap to block did not have a slight miss alignment/step, installed the bearing and others in the block and dropped the crank in, measured crank end float at 0.018”, then installed the #3 cap with thrust bearing, re measured crank end float is now 0.001”.. Block has been align bored and prepped however should the #3 main cap have such an offset? I would have thought the front and rear surfaces should have had a smooth transition?

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#2413164 - 12/04/17 02:45 PM Re: Small block thrust bearing cap alignment [Re: crash520]
MR_P_BODY Offline
Master

Registered: 06/13/03
Posts: 50756
Loc: Romeo MI
Originally Posted By crash520
Guys, ref 360, thrust bearing cap to block alignment. I have ARP mains studs, without bearings fitted I noticed the surfaces front and rear of the #3 bearing cap to block did not have a slight miss alignment/step, installed the bearing and others in the block and dropped the crank in, measured crank end float at 0.018”, then installed the #3 cap with thrust bearing, re measured crank end float is now 0.001”.. Block has been align bored and prepped however should the #3 main cap have such an offset? I would have thought the front and rear surfaces should have had a smooth transition?


Put the crank in it and snug the caps.. then use
a mallet and hit the crank back and forth a couple
of times then measure your end play and check your
# 3 bearing
wave
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#2413172 - 12/04/17 03:06 PM Re: Small block thrust bearing cap alignment [Re: MR_P_BODY]
crash520 Offline
member

Registered: 10/26/13
Posts: 185
Loc: Brisbane Australia
Thanks Mr P, yep that’s what I did, the #3 cap will not “float” and settle in as such prior to tightening, what I have now is the upper back side of the thrust bearing doing the work and the lower front side of the bearing doing the work, not full contact, and like I said, with the bearing shell in the block I have 0.018” install the cap snugged down then slightly back the nuts off, tap the crank back and forth, re snug the nuts and have 0.001”, I can add clearance by carefully swiping on a surface plate one side of the bearing shell.
Is it ok to only have one half of the bearing handling thrust?

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#2413173 - 12/04/17 03:10 PM Re: Small block thrust bearing cap alignment [Re: crash520]
TRENDZ Offline
top fuel

Registered: 01/24/05
Posts: 1668
Loc: Milwaukee WI
No. You will wipe the oil off of the surface like a scaper.
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#2413174 - 12/04/17 03:12 PM Re: Small block thrust bearing cap alignment [Re: crash520]
crash520 Offline
member

Registered: 10/26/13
Posts: 185
Loc: Brisbane Australia
That’s what I’m thinking

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#2413183 - 12/04/17 03:28 PM Re: Small block thrust bearing cap alignment [Re: crash520]
dvw Offline
master

Registered: 03/16/06
Posts: 6994
Loc: MI, usa
The studs are most likely larger shank diameter than the original bolts. Open up the holes in the cap. Then when you seat the cap you can move it where it needs to be. Make sure to seat it with cap moved forward.
Doug

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#2413186 - 12/04/17 03:47 PM Re: Small block thrust bearing cap alignment [Re: crash520]
crash520 Offline
member

Registered: 10/26/13
Posts: 185
Loc: Brisbane Australia
Thanks Doug,
I did notice without the crank installed and having the caps installed, the studs on #3 can’t be wound out like the others, i.e, there is binding in the hole of the cap, this I also don’t like.
So if I open up the cap holes on #3 in order to align the cap with the block, thus removing the bearing half offset to prevent wiping oil off like a scraper, I’ll be left with 0.018” end float on the crank, are std diam with oversized thrust available?

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#2413194 - 12/04/17 04:01 PM Re: Small block thrust bearing cap alignment [Re: crash520]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 30947
Loc: Bend,OR USA
Try loosening the nuts up on that main bearing cap only and hitting the front and back of the crank with a hammer on a block of wood to see if you can get more end play with the main cap loose, if so then try barely tightening, 10 to 25 Ft lbs torque or 100 to 250 inch lbs torque, one nut up only and see if it limits the end play or not. If it doesn't then tighten the other nut up the same amount and try again scope
If it then has no end play after that I would suspect the cap or blocks are not machined square to each other making it impossible to get the proper, .004 to .010, end play needed with new main bearings scope work
I have seen that here locally after having a block aligned honed down runaway puke
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#2413211 - 12/04/17 04:44 PM Re: Small block thrust bearing cap alignment [Re: crash520]
CMcAllister Offline
top fuel

Registered: 12/30/05
Posts: 2360
Loc: Fulton County, PA
Never had this issue on mine. ARP studs didn't create any problems. Bump the crank back and forth to align the bearing halves. Also need to use a large screwdriver or bar to push the crank forward while tightening. .018 is a bunch. Shouldn't have to put the other half in to fix that. Someone would really have to screw up the cap during line boring. Does the cap look square to the bottom surface of the block? I assume the cap is original to the block and putting it on the block correctly?

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#2413225 - 12/04/17 05:27 PM Re: Small block thrust bearing cap alignment [Re: crash520]
dvw Offline
master

Registered: 03/16/06
Posts: 6994
Loc: MI, usa
Originally Posted By crash520
Thanks Doug,
I did notice without the crank installed and having the caps installed, the studs on #3 can’t be wound out like the others, i.e, there is binding in the hole of the cap, this I also don’t like.
So if I open up the cap holes on #3 in order to align the cap with the block, thus removing the bearing half offset to prevent wiping oil off like a scraper, I’ll be left with 0.018” end float on the crank, are std diam with oversized thrust available?

Put the bearing shell thrust surface on a piece of 240 grit sand paper against a pane of glass. I used my garage window. The last one I did (currently in my 900hp 572") had a surface that was even close to flat. Didn't take to much to bring it around.
Doug

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#2413335 - 12/04/17 09:04 PM Re: Small block thrust bearing cap alignment [Re: dvw]
dartman366 Offline


Registered: 01/18/04
Posts: 13119
Loc: Mt. Vernon, Ohio
Originally Posted By dvw
The studs are most likely larger shank diameter than the original bolts. Open up the holes in the cap. Then when you seat the cap you can move it where it needs to be. Make sure to seat it with cap moved forward.
Doug
thats how I fixed mine.
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#2413351 - 12/04/17 09:39 PM Re: Small block thrust bearing cap alignment [Re: crash520]
crash520 Offline
member

Registered: 10/26/13
Posts: 185
Loc: Brisbane Australia
Thanks guys, let me measure a few things up, I also have a set of OEM cap bolts, I’ll insert them just for giggles and see what difference that makes and come back with findings

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#2414255 - 12/06/17 01:03 PM Re: Small block thrust bearing cap alignment [Re: crash520]
crlush Offline
pro stock

Registered: 04/11/05
Posts: 1238
Loc: Michigan
I had a 340 align honed and when the guy ground the thrust cap he didnt cut it at 90 degree to the thrust area so when you would tourque that cap it would pull it over and remove all the clearance, took a bit of work to fix the f up.

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#2414327 - 12/06/17 03:35 PM Re: Small block thrust bearing cap alignment [Re: crash520]
crash520 Offline
member

Registered: 10/26/13
Posts: 185
Loc: Brisbane Australia
Thanks guys, I’ll have a better look on the weekend, I have managed to get more end float by leaving the cap nuts loose and dead blowing the crank but still not right, does anyone know the width of the thrust bearing as new? What they should be?

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#2414366 - 12/06/17 05:19 PM Re: Small block thrust bearing cap alignment [Re: crash520]
CompWedgeEngines Offline
master

Registered: 11/03/04
Posts: 3466
Loc: Syracuse,NY
Originally Posted By crash520
Guys, ref 360, thrust bearing cap to block alignment. I have ARP mains studs, without bearings fitted I noticed the surfaces front and rear of the #3 bearing cap to block did not have a slight miss alignment/step, installed the bearing and others in the block and dropped the crank in, measured crank end float at 0.018”, then installed the #3 cap with thrust bearing, re measured crank end float is now 0.001”.. Block has been align bored and prepped however should the #3 main cap have such an offset? I would have thought the front and rear surfaces should have had a smooth transition?



Just wondering, was this the original cap for the block? if not, it could very well affect that locating. Look at a bunch of caps,and you'll see the holes all over the place in them. ( think like looking at core shift in a part)

Most likely, as mentioned, you will need to ream ( an adjustable blade reamer works fine if you have access) or drill the cap, so that it can properly locate itself.The registers hold the cap in the block and locate it anyhow, the bolts and studs keep it all together. Once you open up the holes, the cap will float, then you can set the thrust with a deadblow hammer. I always start with the crank snout, then back to the flange. Dont be afraid to hit it either, you wont hurt it. You will immediately see the crank spin more freely after you set the thrust from the back.
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#2414817 - 12/07/17 03:03 PM Re: Small block thrust bearing cap alignment [Re: crash520]
crash520 Offline
member

Registered: 10/26/13
Posts: 185
Loc: Brisbane Australia
Ok, small update, so I backed the cap nuts off and deadblowed the crank fire and aft with a little more vigor, now I have 0.005” end float. HOWEVER, what still concerns me is the fact that when I put the bearing halves in the block and installed the crank without caps in place I had 0.018” end float!, now that tells me that the bearing cap is going to take the force of the crank thrust, in my mind I’d rather the block take work load than a cap which could be made walk fore and aft possibly???, it’s a brand new eagle 4340 forged crank, is there oversized thrust bearings????

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#2414909 - 12/07/17 05:42 PM Re: Small block thrust bearing cap alignment [Re: crash520]
dvw Offline
master

Registered: 03/16/06
Posts: 6994
Loc: MI, usa
Did you enlarge the cap holes?
Doug

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#2414918 - 12/07/17 06:04 PM Re: Small block thrust bearing cap alignment [Re: crash520]
crlush Offline
pro stock

Registered: 04/11/05
Posts: 1238
Loc: Michigan
I would say your good.

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#2415027 - 12/07/17 09:45 PM Re: Small block thrust bearing cap alignment [Re: crash520]
crash520 Offline
member

Registered: 10/26/13
Posts: 185
Loc: Brisbane Australia
No not as of yet, I need to pull the crank out and have a better look at the whole thing this weekend

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#2415452 - 12/08/17 07:12 PM Re: Small block thrust bearing cap alignment [Re: crash520]
qwkmopardan Offline
super stock

Registered: 03/26/08
Posts: 851
Loc: Affton MO
I have had this before. Machine shop had a chip or burr on grinding table for removing material on cap parting line. I had .009 endplay until snugging bolts and then nothing. Block will need to be re align honed. Take a thrust bearing with you and have them cut the cap parting line with the bearing loaded in cap. That will square it for sure. Bearing will probably not be able to be used as some material will be removed from it as well.

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