1592 crankshaft end play / end float

[mightyohm]

I just installed the crank on the 1592 I am rebuilding.

I measure 0.004" end play. Maybe just a hair over. I confirmed by measuring with both a feeler gauge and dial indicator. I am re-using the existing thrust washers which show some slight wear.

The WSM specs 0.002-0.004" end float, so I am at the high end of the range, maybe slightly outside of it.

Is 0.004" cause for concern? I know the 1725 has a much wider acceptable range.

What is the thickness of stock/standard thrust washers? I'm wondering if simply purchasing new replacements would take up the extra clearance if necessary. (Are replacements available?)

As an aside, I also measured my main bearing oil clearances with plastigage, and measured approx 0.0025". This is also at the high end of the range permitted in the WSM, but most texts I have consider this clearance to be acceptable. Is this clearance ok?

 

[RootesRacer]

I'd be surprised if a used set of thrust bearings yields .004" clearance.
The only thing you could do would be to get .005 thrust bearings and use only 1 of them and a light grind to it. That assumes that you have .004.

.0025 is on the ragged edge, I'd mic it to be sure, plastigage is not known
to be that reliable. if it is .0025 you can count on lower than ideal idle oil pressure.

 

[mightyohm]

I doubt the thrust washers have many miles on them, judging by their appearance. I double checked and got 0.004" again. The question is - should I try to improve or leave as-is?

 

[RootesRacer]

The proper way to measure the clearance is with a caliper across the thrust to thrust dimension of the center main bearing. You then measure the block web thickness, add the sum of the two thrust bearings and subtract the cranks thrust journal dimension.

Neither feeler gauges nor dial indicators are very accurate measures because there are other items that prevent the crank from easily hitting its positional extremes.

If you can prove to yourself that you have .004 or less by component measurements then I'd leave it alone at that spec.
If its looser, you will have significant RPM drop when depressing the clutch.

 

[RootesRooter]

I'd first fit new stock thrust washers and see if there's still an endplay problem.

Did you have the crank machined? You had mentioned to me that other areas of the PO's rebuild were iffy. Regardless, I'd at least get the journals mic'd. I've read of new bearings sometimes not being accurately sized. Maybe you'll luck out and you just need another set of bearings. If not, I'd take the crank out and get it ground to the next size up.

Might as well do the rebuild right the first time and not have to revisit it again in a couple of years when the oil pressure gets too low and/or it starts to rattle.

 

[mightyohm]

Based on the advice of my local machine shop, I got the crank polished but not machined.

What is the thickness of a new STD size thrust washer?

 

[V6 JOSE]

Now that you got your crank polished, make sure that you clean out the oil holes throughly. It doesn´t takemuch of the grit from the polishing belt in the oil holes, to mess up the bearings. Pipe cleaners are good for cleaning them out.

Jose

Based on the advice of my local machine shop, I got the crank polished but not machined.

What is the thickness of a new STD size thrust washer?

 

[RootesRooter]

Are the bearings new?

 

[mightyohm]

Yes, the bearings are new (020 over). King brand.

 

[sunbby]

The proper way to measure the clearance is with a caliper across the thrust to thrust dimension of the center main bearing. You then measure the block web thickness, add the sum of the two thrust bearings and subtract the cranks thrust journal dimension.

Neither feeler gauges nor dial indicators are very accurate measures because there are other items that prevent the crank from easily hitting its positional extremes.

Can you elaborate on that? The WSM does prescribe the feeler gauge procedure for checking the end float.

 

[RootesRooter]

If memory serves, wasn't your engine's first symptom the drop in rpm's when you depressed the clutch?

I think I'd take RootesRacer's advice on using a .005-over thrust washer that's been lightly ground.

Did the machinist who polished the journals also measure them? I once bought a Series V that rattled a bit, tho the engine had very few miles on a rebuild. Turned out the rod journals had been over-ground by about .004.

 

[mightyohm]

Spoke to my machinist today. He feels that 2.5 thou oil bearing clearance is within specifications and should not be cause for concern. The crank was measured and found to be within specifications. I am planning on checking his work with a micrometer this weekend.

Rootesrooter - yes, crank end play was a concern before the rebuild due to RPM drop with clutch depressed. However, with the engine in the car I measured 0.003" end play - I am measuring slightly higher end play now, but it's still within specs. Any idea how bad the end play needs to be before there are issues? I suspect it would have to be a tad bit higher than 0.004", which is imperceptible without a dial indicator!

 

[mightyohm]

Pulled the crank out and measured everything separately.
Crank thrust face separation 1.626"
Block thrust face width 1.437"
Thrust washers (lightly used) 0.093 + 0.092" = 0.185"

End play = 1.626 - 1.437 - 0.185" = 0.004"

This agrees with my dial indicator and feeler gauge measurements! So, it appears that I truly am right at the upper end of the spec range.

The question is - run it as-is with the existing thrust washers or grind down a new 0.005" over thrust washer to take up about 0.002" clearance? Is it worth the trouble?

Main bearing clearances:

I measured everything. This is my first foray into using micrometers and a dial bore gauge, so it took a while to get reliable measurements! I practiced many times and feel pretty good about the final data I collected.

Block bearing bores measure 2.3955-2.3970" without bearings installed. Spec limit is 2.3955 so I'm at or over the spec on all bores.
Crank is measuring 2.2287-2.2290" on all main journals, which is at or just under the min spec (2.2290").
Main bearing shells measure 0.0820". (020 under)

Calculated main bearing clearances are 0.0027 - 0.0033". This is higher than spec (0.0025") on all 3 main bearings.

So it seems like I have a combination of parts which are just out of spec on both extremes (too large on the block, too small on the crank), resulting in excessive oil clearance.

The machine shop is suggesting that I leave the crank as-is and bring the bores on the block back into spec by facing the saddles and honing slightly. That should bring the oil clearance within spec.

 

[mightyohm]

Update.

I brought the crank and block back to the machine shop and had them hone the main bearing bores back into spec. (Essentially an Align bore). They didn't touch the crank. Now my main bearing clearances are all in the 0.0015-0.0020 range. Good?

I bought 0.005 oversize thrust washers and using a surface plate, sanded down one of them to about 0.094". This brought my crank end play down from 0.004 to 0.002, the min spec.

Lastly, I checked my rod bearing clearances. Found a potential issue, they are all tight, ranging from 0.0012-0.0018. My machinist insists that the clearances will be ok and that I should just run it, but I am a hair under the wsm spec of 0.0015 min on the tightest rod. The crank turns smoothly and does not bind. . What does the collective wisdom of the forum say?

 

[RootesRacer]

I say go with it.

 

[mightyohm]

Thank you, that makes me feel a bit better. What would you consider to be the hard limit on minimum clearance?