Topic: Plastigauge??

[slikwilli420]

I am anxiously awaiting parts for my bottom end and want to be ready to check everything before assembly. I have a crank that came from cases with all B shells going into a set of cases marked for all B shells, but want to check clearances anyway.

This kit: https://www.summitracing.com/parts/cle-mpg1/overview/

Is is a good one? Does this do one journal only, meaning I would need 5 kits? Do I need to do each half of each journal or just once per journal?

This is a totally foreign thing that I need to get a handle on before I put this thing together.

[Jerry Rxman Griffin aka MuthaF'er]

That's the stuff. It's not a "kit". It's a piece inside the package. Just be sure you get the right diameter. You should only need one but get a spare. Put it in multiple places for each journal. Easy and good.

[bwaller]

You want the green plastigage, not sure what that color was. It's a very thin rod of material in that paper sleeve. Cut off pieces of the sleeve the width of the bearings you're measuring, then open and gingerly handle the material into place.

[slikwilli420]

The 001"-003"sold be the right stuff, yes?

[bwaller]

Yes.

[MRieck]

If your racing I'd set it up on the loose side.....like green bearings for a variety of reasons.

[slikwilli420]

If your racing I'd set it up on the loose side.....like green bearings for a variety of reasons.

What clearance should I shoot for then?

[Rocketman]

Not sure about 750's but the service limit on 550's is .003".  My motor had green bearings when I tore it down.  In an effort to tighten up the clearance I put blacks in and got it to between .001 and .0015.  Then, when I assembled the bottom end and torqued the 8mm case bolts to 18 ft lbs I found the crank to be locked up!  Put new greens in and my clearance was .002.  When the cases were assembled and torqued the crank turned over with no drag.  So, I'd say .002 to .003 is the sweet spot.  As Mike says, looser is better.  Here is a link to my experience with too tight bearings.

http://forums.sohc4.net/index.php/topic,135652.0.html

[danyo]

Yeah, target for 0.002". Less oil- more wear.

Sent from my SM-N900T using Tapatalk

[Bill/BentON Racing]

Here you go

[bwaller]

I shoot for 0.0017- 0.0018" on the race engine.

[slikwilli420]

I shoot for 0.0017- 0.0018" on the race engine.

How do you do that with the gauge they supply? I suppose you could extrapolate the difference in width of the 0015" and 002" marks to figure out how wide a 0017" would be and use that, measuring with calipers. Martin is saying a little wider for a racer, now Im all confused. I really only want to do this once, especially if I need to order bearings.

[bwaller]

Yes it will never be an exact science measuring against the marks on the sleeve. You will find a balance between marks.

In the end unless have a complete supply of bearing sizes and an incredible amount of time on your hands there is some "settling". I try to have even clearance across all 5 journals and between rods. Again not easy, but within a 0.0001 if possible.

I mentioned 0.0017-0.0018 because that's where most ended up with new green shells the first time. I changed one rod for the next tightest bearing shells to even those out.

Just another step in the process, don't worry-be happy!!

[BPellerine]

do you have any of the old bearings around with the color markings on them,you could practice with those to get a feel for it,sounded complicated the first time I tried,but it is really quite simple,you can only get so close with the bearing selection,bill

[Bill/BentON Racing]

Here you go

[PeWe]

I measured crank and did a plasti gauge test when installing another crank 2 years ago. Had green bearings in first, a little bit loose. Changed to brown.
http://forums.sohc4.net/index.php?topic=155014.0

Update 6 month later when I opened the engine again to open up for JMR cyl block.
I noticed that some bearing shells had scuffmarks. I think it was the inner.  I replaced brown with green and I'm sure that was the correct measure.

I could reuse the browns in my K2 build where my old K6 crank lives, it has had browns before.

[Swoop]

Here you go

Hi Bill,
Do you put the plastigauge on top and bottom bearing shells....or just the bottom?

Steve

[Bill/BentON Racing]

K  put it on the crank which is sitting in top of case 1/2.....then install bottom and torque to spec I want in proper sequence.

[Swoop]

Thanks

[slikwilli420]

K  put it on the crank which is sitting in top of case 1/2.....then install bottom and torque to spec I want in proper sequence.

Im still confused. So you check both the top and bottom shells for each journal, or just one side?

I got my stuff ordered per the recco from Bill.

[danyo]

One side only, you can't put two different color bearings on one journal. Don't turn the crank with plastigage in place.

Sent from my SM-N900T using Tapatalk

[slikwilli420]

One side only, you can't put two different color bearings on one journal. Don't turn the crank with plastigage in place.

Sent from my SM-N900T using Tapatalk

Got it! Makes sense. Also it stands to reason that the journal is round, the hole in the cases is round and the shells are round, so checking one side should be sufficient.

[Rocketman]

I generally lay the crank in one case half then put a piece of plastigauge on each journal.  Set the other case half on and tighten up the fasteners to the torque specified.  Do not turn the crank.  Undo the fasteners, remove the case half, and compare the crushed plastiguage to the chart on the packaging. 

Here is a good article on crank bearing clearance. 

https://www.mahle-aftermarket.com/media/local-media-north-america/pdfs/cl77-1-205r.pdf

[slikwilli420]

I generally lay the crank in one case half then put a piece of plastigauge on each journal.  Set the other case half on and tighten up the fasteners to the torque specified.  Do not turn the crank.  Undo the fasteners, remove the case half, and compare the crushed plastiguage to the chart on the packaging. 

Here is a good article on crank bearing clearance. 

https://www.mahle-aftermarket.com/media/local-media-north-america/pdfs/cl77-1-205r.pdf

Interesting indeed! It would seem that with my race application and the fact that I run Rotella 15-40, a little bigger clearances wont hurt anything, as long as I still observe proper warm up times and don't go tear-assing out of the pits on a cold engine.

[bwaller]

Oh #$%*, not Rotella!