2F Rebuild - New rings/bearings running loose to spec?

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Working to re-assemble my 2F...but while spot-checking all the measurements for the rings and bearings, some things are amiss on both fronts.

Rings:

Block was bored .020/0.5mm overbore, and a bore gauge shows that it's there - ended up at 94.54, which is on the tight side of the 94.5-94.7mm spec for that bore. The .020/0.5mm pistons also check out. The pistons came with unknown-manufacture rings, but I ordered the Hasting .020 bore rings...however, both have an oddly wide ring gap.
  • FSM Spec: 0.2 to .038mm
  • Hastings: Top rings - 0.61mm, bottom rings - 0.56mm
  • Unknowns : Top rings - 0.51mm, bottom rings - 0.41mm
The random rings are better...but both are quite a bit wider than expected, which seems odd as the bore checks out, and both are .020 ring sets.

Bearings:
Seeing some oddities with the crank as well - the rod bearings checked out ok, but the mains (Clevite MS-1429G) are running loose, especially the center two. The crank itself checks out with some quick measurements, generally on the large side, so seems like minimal wear there. (Machine shop also reached that conclusion back when it was there for machining and cleaning.)
* One - 2.637 in (Spec: 2.6367-76)
* Two - 2.696 in (Spec: 2.6957-67)
* Three - 2.755 in (Spec: 2.7548-57)
* Four - 2.814in (Spec: 2.8139-48)

Specs look for .020-044mm on the plastigage, but I'm in that .05-.07 range. Given the crank itself is on the larger side, it seems odd that the standard bearings are running loose. Checked them twice, generally same results.

Any ideas on either of the rings or the mains, as to why the parts that seem like they should be right, aren't? The rings are especially odd...bearings are a bit tighter tolerance. Going to try re-checking the crank one more time after dinner, going to the higher end of the cap torque range...I'd used 100 ft/lbs, and the range is 90-108.

PXL_20210721_204007441.MP-COLLAGE.jpg
 
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Double checked the rings, no new info there...cylinders are nice and straight after machining though. 😆

Picked up some fresh plastigage, and rechecked the new main bearings with the high end of the cap torque...same results. I remembered that the original bearings were in a box from the machinist, and 3 out of the 4 sets were good enough to plunk back in to compare...the #2 set was dinged up, so couldn't use those.

Annnnnd...with those in there, they actually came out generally within spec...which I found very odd. Just to re-confirm, I dunked the new ones back in, torqued the same...and back to running loose. 🤔

Looking at the Clevite catalog, the MS-1429G set is the correct one. Color me confused on both fronts...the fitment of both the rings and the mains are just, odd.

Screen Shot 2021-07-21 at 8.08.06 PM.png


Plastigage with the old bearings back in for reference:

old.jpg
 
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Going to be away from the shop for the week as well next week, so digging a bit more and will likely push to assemble when I'm back in the shop.

Poked Hastings to see if they have any thoughts on the rings - the slightly overbore overbore (94.54 vs 94.50mm) would add ~.007" to the ring gap, but even accounting for that, they're starting out at the high end. They'd basically be at the 0.44mm right out of the gate for a 94.50 bore, which seems odd. I'm sure they're serviceable as-is, but if we can tighten them up a bit, it would be a good thing.

I also ordered up another set of main bearings just to see if the set I got in May is off for some reason. The fact that the worn originals check out, but not the new ones, is definitely odd. For the price ($70), it's worth the peace of mind methinks.
 
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Rechecked a few things after lunch - all the bearings (old and new) are marked as STD, nothing out of the ordinary.

The machinist/engine-guy suggested trying a small sliver/strip of soda can aluminum vs the plastigage as another test. The alu' is softer than both the bearing and the crank, and it's right around that .002-0.003. If there's drag on the crank, clearances are in the ballpark...if it spins, they're loose.

...with the #2 and #3 bearings, the crank was free. If I put in the old bearings, not so much...so something is for sure amiss with those new center two. :confused:
 

SlapSmak

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I have built a few motors, all of them with much tighter tolerances than an F motor, so bare with me.

1. what kind of soda can did he suggest? a coke can, a mic ultra can? don't use the soda can test, that is a stupid ass shade tree mechanic method that was used back in the 40s and it can gouge the crank journals. Plastigauge is used by every engine builder on the planet that is actually worth a s***, and it is accurate, and it is cheap.

2. did you mic the bearings? I would mic the old and the new. Many times, crank journal bearings will be marked standard, but the builder will use 2 or 3 different boxes to pull bearings from to get a better fit. The bearings will have tolerances just like the crank journals and doing a little math and using different boxes will get you a better fit. Maybe even going up to the next size and just using the bigger for the center 2. Your journals are different sizes, so you have to compensate for that.

3. Is going up one more size on the rings available? If so, once they are compressed, you will get a much smaller gap, maybe even one you have to wet sand with emery paper to get a tight gap.
 
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I have built a few motors, all of them with much tighter tolerances than an F motor, so bare with me.

1. what kind of soda can did he suggest? a coke can, a mic ultra can? don't use the soda can test, that is a stupid ass shade tree mechanic method that was used back in the 40s and it can gouge the crank journals. Plastigauge is used by every engine builder on the planet that is actually worth a s***, and it is accurate, and it is cheap.

2. did you mic the bearings? I would mic the old and the new. Many times, crank journal bearings will be marked standard, but the builder will use 2 or 3 different boxes to pull bearings from to get a better fit. The bearings will have tolerances just like the crank journals and doing a little math and using different boxes will get you a better fit. Maybe even going up to the next size and just using the bigger for the center 2. Your journals are different sizes, so you have to compensate for that.

3. Is going up one more size on the rings available? If so, once they are compressed, you will get a much smaller gap, maybe even one you have to wet sand with emery paper to get a tight gap.
1 - agreed, was just an additional (shadetree) check to confirm what the plastigage was already telling me. Figured low risk as the alu' was softer than the bearing which is softer than the crank...and the bearings (both original and new) were not getting used at this point.

2 - not yet, don't have the right mic to check them on hand at the moment...but clearly the replacement is thinner based on the crank fitment tests. Unfortunately, finding parts for the ol' 2F isn't always easy...I haven't seen much options for alternate bearings aside from the .25's for machining the crank down. I did find a set of old-stock STD bearings from a different manufacturer as well for fairly cheap, so I've got two sets on the way to dabble with once I get back to the shop to hopefully find a winner.

3 - Haven't heard back from Hastings, but that's likely the play - get some 030's that'll likely need filing (which is fine by me). Only risk there is more delays - last time, the rings took over a month to ship out...why, not sure, as the box was marked as 2019 manufacturing. 🤔
 
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2. did you mic the bearings? I would mic the old and the new.

Yeah, this. Mic everything in three places to get an overall diameter. The best machinist I
know almost never relies on Plastigauge.

Your crank could be bent/misaligned ever so slightly. Or maybe the block was not aligned correctly when it was bored. Just throwing this out.
 
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Fairly certain the crank is OK - it passed runout checks, it passes dimensional checks with the mic, and the old/original bearings also pass clearances at multiple different rotations of the crank...they're on the high end, but they do pass. Not too unexpected, it had 120k on the clock. The new bearings also showed the same result over several checks at multiple rotations.

Unless I'm missing something, the cylinder rebore shouldn't have any impact on the mains not passing clearances - they weren't touched in the process, and there's no impact between the two when it's just the crank in the block.

Directly mic'ing the bearings is indeed the most accurate, although these low revving 2Fs are more like tractor engines. 🙃 Going to see if I can get a few measurements this afternoon with what I have, but TBD.
 

Engineer8000

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Interesting that Toyota went with 5 main bearing sizes with the 3F block. Determined for each journal by the numbers stamped on the crank and block. I used Toyota bearings in the 3FE.

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1627061386856.png
 
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Unless I'm missing something, the cylinder rebore shouldn't have any impact on the mains not passing clearances - they weren't touched in the process, and there's no impact between the two when it's just the crank in the block.
I was referring to the main bearing bores. I probably should have said "line bored" or "align honed" or something. I'm bad with terminology.
 
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No worries, that makes more sense. I don't believe that was touched, just the cylinder bores.

I did look up OEM bearings from Toyota, but they seem to be no longer available - at least that I found. I did catch that the 3F changed the system a bit too while digging around for the 2F.

Looks like the replacement replacements should be here midweek next week, will see what those tell us. No ship date for the rings yet, hopefully Monday.
 

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