Main bearing thrust bearing too tight!!

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Nick M.

Nick M.

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Do i have the wrong bearings? 76 360 block bearing p# 4999m 10 under main bearings crank was ground 0.010 Crank binds on the thrust surface when set into the block, is the thrust surface supposed to be 0.010 under as well as the rod and main journals? This the first chrysler i have attempted to build, have done many chevys and have never encountered this problem before...bad machine work? bummed was hoping to assemble the bottom end this weekend :(
 
upon further inspection this is what i have found. Main bearing is an ACL 5M1266P-10 should be correct for 74+up 360 block casting # 4045601 360 date code 8-11-76 The thrust bearing fits on thrust journal nicely with the bearing in hand, bearing shell fits very tight on main cap and block. Once installed in block and on cap the bearing no longer fits on thrust journal of crank. Crank is ten under main and rod journals. Block was not align honed just checked (by machine shop) and found to be in tolerance. When looking closely at main cap and block it appears that the thrust bearing mounting surface (sides of main cap) are slightly wider at their outer edge flaring bearing out slightly just before it seats. I will try to get some pics.
 
Here is a pic of the area in question..

thrust main2.jpg
 
Make sure you sand the OUTSIDE Flange of the bearing. You want the bearing to be TIGHT on the block and Cap!
 
Nick M. said:
Here is your pic of the area in question..
Click to expand...
Look close were the bearing goes on... Just to the left of your arrow if you look at the curved part were the bearing fits in there is a ding right were the bearing fits in ... I have seen guys use a hoist with a hook in the main cap area to lift the block around.. Please check this location as it looks like its not a sharp edge like the rest of the opening... Also check were the bearing tabs are at as just a little dirt in there will change the clearance... Just my opinion that it is a ding just to the left of your arrow at least I think I see a mark there right on the edg, I could be wrong but check it please... John(onecatnodog)
 
I will check very closely for any burrs/dings or high spots tomorrow.. fwiw the bearing is tight on both the block and cap. I know they should fit snugly but these are the first that i have encountered that i could not install by hand. This motor was complete and assembled when i got it crank spun freely prior to disassembly, the only part new to this puzzle is the bearing.. I guess it is possible that bearings i have were packaged wrong i will get some pics of the bearings tomorrow.
 
Call me tomorrow at 720-934-3540 and I will help you over the phone if you like.. I worked at a machine shop when I was going to auto college and built engines for them.. I still do it on the side... I will help you... John(onecatnodog)Collins
 
I'd get another bearing once you deburr the area. The bearing should sit tight in the bore but not because it grabs the sides... It has tension on it because of the bearings "crush". If it slides into the crank nice, I think there's an issue with the block itself...
 
There is tool chatter showing in the finish. That will wear down to smooth fairly soon and allow more oil in initially. Is that a modern planned method to the madness ?
I'm still not comfortable with it. I would exchange it for a higher quality part or atleast compare it with another from the same vendor. Good luck
 
Did some careful inspection today and guess what i found.... just what onecat said some burrs and dings to both the main cap and block. I spent some time cleaning things up a bit and it made a big difference, the bearing halves now slip into place firmly just like they should. I set the crank into place for a clearance check and it looks good, a 0.002" feeler gauge slips between the crank and the thrust bearing. The mains measure 0.0015" I will check end play tomorrow with a dial indicator and see what i get. Thanks everyone for your help and suggestions, John thank you for the offer to call, glad i was able to get it handled on my own (with your help:-D). Maybe i should find a new machine shop.
 
Don't forget to set the thrust bearing after assembly by prying the crank fore and aft then check axial play.
 
onecatnodog said:
Look close were the bearing goes on... Just to the left of your arrow if you look at the curved part were the bearing fits in there is a ding right were the bearing fits in ... I have seen guys use a hoist with a hook in the main cap area to lift the block around.. Please check this location as it looks like its not a sharp edge like the rest of the opening... Also check were the bearing tabs are at as just a little dirt in there will change the clearance... Just my opinion that it is a ding just to the left of your arrow at least I think I see a mark there right on the edg, I could be wrong but check it please... John(onecatnodog)
Click to expand...


Good eye ONECATNODOG!!!!!!!!!!!
 
Glad I could be of some help here on this new to me site... Many machine shops use a hoist with a hook and catch the block by the main caps... Just something that needs to be checked when building a engine... Make sure that you go through the check list like I said, it will save you time and work in the long run... John(onecatnodog)Collins Here is some advice that I gave last week on a cam bearing issue... Use this as a guide line... I just copied it from my post and pasted it here to save time... It works and I use it... :clock:
Built many engines in my day at Engine Service and Supply a machine shop that was here in Colorado when putting myself through Denver Auto and Diesel Collage... Still do them on the side.. Very rarley do I have to use the cam knife but have used it on occation... Cams needs to turn freely by hand just like the crank with out the oil seal in place or rods and pistons... BY HAND! Easy turn means more horse power and less ware on start up or chance of sticking a bearing... Hot tank the block and the cam bearings are gone.. Before hot tanking, first remove all core plugs and galley plugs to get a good job.. When it comes out of the hot tank I use a wire wheel on a drill to clean all un machined surffices then chase all bolt holes with taps then use brushes on all oil passages and all bolt holes cleaning them with solvent.. Then wash the block with soap and water... Air dry all holes and galley lines... Here is a big tip! Use your drop light and LOOK through all passages that you can, light at one end and looking through the other.. Seeing if it clean or not... Check all cylinder bores for bad places and check that the cam bearing are installed correctly with the oil holes in the correct place.. Check for cracks every were... A super clean block makes it easer to spot flaws.. Test fit a lifter threw all lifter holes for free movement... If you do all of this before the actual build it will limit failure.. It is time consuming but will save you in the long run... Just my opinion.. :read2:eek:necatnodog
 
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