Engine Rebuild - Difficult to Turn Over

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deraleak
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Joined: April 16th, 2017, 10:05 am
Stroker Displacement: 4.6
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Engine Rebuild - Difficult to Turn Over

Post by deraleak »

Hi Guys!

I stroked my cherokee a year ago, its up and running but still has some issues. However, today I come to the board looking for answers regarding a different motor... however, it is all relevant to a rebuild or a stroker project.

When I stroked my 4.0, the crank bearings, the piston rings, everything was in specc when I was building the motor. I used the Guru on this site, Russ Potenger (Was a wonderful resource, huge help, I will recommend him 10/10) to help me spec parts, and ended up with a little over a 4.6L displacement. The motor took approximately 35lbs of torque to turn over :shock: Hoewever, it fired right up when I tried to start it.

Im now working on an inline 4 cylinder rebuild, and it is doing the same thing. All bearings are within spec, I used alot of assembly lube, all of the pistons slid right in, and according to a local shop, it SHOULD turn over by hand using the harmonic balancer as long as the plugs are out. THIS IS NOT THE CASE. This crank also lacks threads on the end, which is what I used to turn the 4.0 over when building it. This engine actually was difficult to turn over even when I loosened the main bearings.

TLDR; Engine isn't turning over, everything is in spec. Please help
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IH 392
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Re: Engine Rebuild - Difficult to Turn Over

Post by IH 392 »

Sounds normal to me?, new motors are tight, I've built some that were so tight they wouldn't turn over with the six volt battery (OLD Ford tractor engines) and we had to put 12 volts to them!
You can get more power out of ANY engine!!!
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StrokerWannaBe77
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Re: Engine Rebuild - Difficult to Turn Over

Post by StrokerWannaBe77 »

this is an old thread so I am not sure if I will get an answer but here goes:
I am in the middle of doing a 4.0L rebuild. The engine had a blown head gasket when I bought it, so I tore into it and realized that I should replace the rod bearings and a few other things while I am doing all this. Well when I went to assemble things I measured the crank shaft rod bearing journals and it appears that two of the journals are bigger than the normal size journal. I promise you I am measuring correctly but I looked at the specs and it seems like the journals are larger than standard. SO my question is have you ever heard of this happening? Any advice on this would be great. I have 4 of the pistons installed and the crank turns over by hand. But the #1 and #4 cylinder if I install the pistons, I can no longer turn the engine over by hand. I mean I can't turn it over even with a wrench on the damper snout.
Did the factory make oversize bearings at any point? Thanks for any help!
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amcinstaller
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Re: Engine Rebuild - Difficult to Turn Over

Post by amcinstaller »

I have read about this but it's not been something that happened on two out of 6 rods (or 7 mains). If you measure the journals, check if a .010" oversize being can fit, you may need to source it at a machine shop?
1980 AMC Spirit Restomod in Progress
SilverXJ wrote:Roller rockers won't help that mess you have created. Nor will God for that matter.
StrokerWannaBe77
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Re: Engine Rebuild - Difficult to Turn Over

Post by StrokerWannaBe77 »

Thanks for replying. So the crank rod journal is measuring oversize, not undersize from the stated standard in the factory repair manual. I am trying to replace the bearings with new bearings at the standard size and I have not had the crankshaft turned.
So trying an undersize bearing (which would be an actual bigger bearing) would not help the situation but be worse. Hope that clarifies...
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amcinstaller
I love JeepStrokers.com!!
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Posts: 576
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Re: Engine Rebuild - Difficult to Turn Over

Post by amcinstaller »

My mistake -- posted after drink :roll:

Yea usually if the journals were TOO SMALL that would be noted by stamping on the block, and as you've mentioned, a THICKER bearing would be used. That however is not your trouble. I haven't come across that before. How much bigger are you measuring?
1980 AMC Spirit Restomod in Progress
SilverXJ wrote:Roller rockers won't help that mess you have created. Nor will God for that matter.
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IH 392
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Re: Engine Rebuild - Difficult to Turn Over

Post by IH 392 »

Are you measuring the journal with a micrometer?, or the clearance with plastigauge?
You can get more power out of ANY engine!!!
ASE Master certified engine machinist, gas and diesel
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