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Another Oil Viscosity Discussion

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Rebel Machine View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rebel Machine Quote  Post ReplyReply Direct Link To This Post Posted: Dec/03/2022 at 7:38am
Thanks for the info guys. I was looking through the old Performance American Style yesterday. I'd classify my engine as Mode 3 "Way Out". The clearance numbers Red Devil provided are very similar to that using the extra 0.0005" for high performance.

Years ago I had an engine eating cam bearings due to excessive clearance on the mains. The bearing manufacturer provide the wrong clearance information and they were set between 0.0035" and 0.0040".

Since I'm using s centrifugal blower it might make sense to use a bit extra clearance on #1. My engine builder is recommending 0.0025" on the mains. As tight as the bearings were on my engine #3 and #5 appear to be perfectly okay as were the rod and cam bearings.

My best guess would be to go with 0.0030" on #1 & #5, 0.0025" on #2, #3 and #4. Probably stay with the 10W30 Valvoline VR1 oil to keep the dizzy gears happy.

-Steve-

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Hurst390 View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Dec/03/2022 at 7:45am
Straight 30 vr1 here
Lets start at the beginning. Was a drill bit ran through the oem main feed holes? I have yet to find a block that has been completely drilled through from the factory.

Yeah wtf is PO? 
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Rebel Machine View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rebel Machine Quote  Post ReplyReply Direct Link To This Post Posted: Dec/03/2022 at 7:47am
Originally posted by Hurst390 Hurst390 wrote:

Straight 30 vr1 here
Lets start at the beginning. Was a drill bit ran through the oem main feed holes? I have yet to find a block that has been completely drilled through from the factory.

Yeah wtf is PO? 



I'll have them double check that.
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Trader View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Dec/03/2022 at 7:52am
PO - Personal Opinion
Must be a foreign thing!
Just like NFG -, Operating Engineers used that all the time decades ago, Not Functioning Good. Believe there is a different meaning now.


Edited by Trader - Dec/03/2022 at 7:59am
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Red Devil View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Red Devil Quote  Post ReplyReply Direct Link To This Post Posted: Dec/03/2022 at 10:49am
Originally posted by Trader Trader wrote:

Never did understand the more clearance on #5 unless they were planning for transmission misalignment?


My understanding is it accounts for additional crankshaft deflections due to the mass-moment effects of the counterweighted flywheel / flexplate plus clutch assembly / torque converter that lead to early rear main issues when all bearing clearances were the same.  

The crank journals should be machined to specs, i.e. rear journal nominal 0.001" smaller than 1-4. 

Now that assumes stock reciprocating assembly and stock flywheel & clutch assembly or flexplate and torque converter assembly and stock front dampener.  Once you deviate significantly from stock, then changes may be needed to suit the application and new build.  

If you are breaking new ground with your build, then it may take several tries to get things right.  Frequent tear-down and inspection is likely in order.  

Hence, why often easier long term to transplant a known engine combination for racing.   Kudos to those that stick with AMC and work it out.

RD.
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