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WF owner 
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Joined: 12 May 2013
Location: Bombay NY
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 Topic: Help needed on assembling an engine
Posted: 04 Jun 2017 at 8:15pm |
I am putting an engine together and I have a couple questions. I have a 201 (WC) block and I am putting a 4 1/2" (WD45) crank in, with 7.25/1 pistons. I bought a crankshaft "shim kit". When I opened it tonight, there were 6 shims; one for each main bearing bolt. The service manual talks about 4 shims. (The original caps had one shim for each bolt.) My concern is over crushing the main bearings. Should I buy more shims before tightening up the rod bolts to check the clearance with Plastigauge? My second question is about main bearing bolt torque. In the service manual, it says 70 ft. lbs. for rod bearing (40 ft. lbs. if they are casselated nuts), but I find no torque for the main bearing bolts. What should the mains be torqued to?
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CTuckerNWIL
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Joined: 11 Sep 2009
Location: NW Illinois
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Posted: 04 Jun 2017 at 8:24pm |
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Put the caps on with no shims or bearings and use an inside mic or telescoping gage to measure top to bottom.
I tried shimming my WC back to standard, but the bore was no longer round with the proper shims. Almost .003 out of round at the worst spot, if I remember right.
I miced each main bore and ended up shimming .006 on each side. Then I ran a sunnen hone in each bore till they mic right top to bottom.
When I bolted up the crank, I had between .0025 and 003 clearance with plasti gauge and it rolled like a dream.
Edited by CTuckerNWIL - 04 Jun 2017 at 8:25pm
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Brian Jasper co. Ia
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Posted: 05 Jun 2017 at 12:51pm |
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Here's another concern, when I did my CA engine years ago, fresh ground crank with new bearings and new shim stacks it would not turn with the mains torqued. With a large carpenter square I could see the center main was definitely not in line with the other two. I just had it line bored like Charlie did except they bored it for no shims. I did the same for the rods.
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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford
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DrAllis
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Posted: 05 Jun 2017 at 3:06pm |
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I think you're corn-fused on what "four" shims actually means. There are shim stacks for each main cap bolt for a total of six shim stacks. Each shim stack consists of FOUR SHIMS glued together. Each shim stack is .010" thick, meaning each individual shim is .0025" thick. If you were to try and change/tighten a shim stack you would peel off a .0025" shim from a stack and then file off the end of a bearing shell to allow for correct bearing crush. The long and short of it is this.....a freshly reground crank (or a brand new crank) needs new main bearing shells and NEW SHIM STACKS AND ALL SHOULD BE WELL IN BEARING CLEARANCES.
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WF owner
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Posted: 05 Jun 2017 at 7:54pm |
OK Doc. Once again, you ae 100% right. I just went out and looked at the shims and couldn't separate them. I came in and showed them to my wife and we were sure they were one piece. I took a new utility knife blade and I was able to separate one corner, proving you right. (They are going to be fun to try to separate one layer at a time!!!) My crank was turned (-.020) and I have new main bearings (also -.020) and a new shim pack. If things ever slow down, I will try torqueing the main caps, with Plastigauge , and check the clearance. This brings me to my next question. What is the torque for the main bearing cap bolts ? I can't find it in the AC service manual.
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CTuckerNWIL
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Posted: 05 Jun 2017 at 8:00pm |
 WF owner wrote:
I just went out and looked at the shims and couldn't separate them. I came in and showed them to my wife and we were sure they were one piece. I took a new utility knife blade and I was able to separate one corner, proving you right. (They are going to be fun to try to separate one layer at a time!!!)
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You shouldn't need to separate the shims for at least 20 years. The full shim pack goes in with new bearings if the bearings are matched to the crank size as you said.
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steve(ill)
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Posted: 05 Jun 2017 at 8:44pm |
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main cap bolts are 85 ft pounds.
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Like them all, but love the "B"s.
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WF owner
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Posted: 06 Jun 2017 at 9:21am |
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Thanks to all for the info. I will let you know how I make out!
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