Who's clocked engine builder? need a bit of a hand :)

[VN_Luke]

Hiya,

Well just going over my new engine - it came assembled as a short motor from the machine shop, but i had to remove the crank for a bit more machining (oil pump drive gear modification)

so while I had the crank out I decided to rip the whole thing out and go over all the clearances, so I knew what they were and how well the motor was machined etc

one thing has caught my eye, though - the bearing for number 5 conrod big end seems to be a bit more worn than it should be from the motor just being cranked over by hand a few times (while sitting in my shed glad-wrapped for about a year lol)

When I get the crank back, I'll measure that big-end journal with the micrometer and likewise measure the conrod big end size ID with the bearings in place, using the dial bore gauge (and with the rod bolts torqued down properly)

The bore on the big end seems to be 'out of round' by up to 0.008mm - which is about the same as all the other big ends.

so my final question is - do these bearings look like the oil clearance is too tight on that journal? And if so - what can be done about it? the bearings are ACL std size + 0.001", and crank has been linished.

Cheers,
Luke

[immortality]

was it assembled dry? i would pack it with vaseline before even considering turning it over

[88GreenVN]

Looks like that bearing has done some work already. Dont know if I'd want to use that one again. But then again I'm only a back yard mechanic so not qualified to give quality opinoin.

[VT-565]

It's f*cked.

When you pulled the crank out, were the bearings lubed or dry?
Also when it comes to measuring the crush on a big end, i'd use plastigauge instead. By all means, mic up the crank journal and clock it (to check for concentricity), likewise with the big end of the rod (torqued up - no bearing shell) to see how good of a job they did if they close-honed the rod.
Let us know what you find.

[VN_Luke]

Yeah I figured the fact that this bearing is worn and the rest aren't is probably a decent indication that it shouldn't be like that.

When I pulled the crank out, all the bearings had a fair bit of assembly lube in them (not goldy oil, but green looking slippery stuff) - mind you it had been sitting there for quite some time... like a year.

Like I said the big end of the rod is 'within spec' (within 0.008mm) with no bearing shells and the bolts torqued up to spec - measured in 4 different points, each 45 deg from the previous. I'm not sure if they close-honed the rod as they're brand new items, but it's worth a measure either way!

Haven't measured with the bearing in yet.

It almost seems as if the cap for the rod was put on backwards or something - but I can't remember which way around it was before i took it out, of course..

I also found another bearing with a tiny spec of foreign material embedded in it, along with a bit of a scratch - as if a tiny bit of a burr had got caught in there

I'll definately double check all the clearances with plasti-gauge, but the problem is that it only measures the clearance in one spot - so while the clearance on 'top' of the big end might be spot on, it might have a tight spot a little off that point. - So I'll measure all round the journals etc and then confirm the measurements with plasti-gauge once they're all determined to be ok.

for now I guess I'll wait for the crank to arrive to do more measuring, and then it looks like I'll be getting another set of bearings.

I'm glad I pulled the thing apart now, though

I assume this kind of bearing wear indicates metal-metal contact?

[VT-565]

Yeah I figured the fact that this bearing is worn and the rest aren't is probably a decent indication that it shouldn't be like that.

When I pulled the crank out, all the bearings had a fair bit of assembly lube in them (not goldy oil, but green looking slippery stuff) - mind you it had been sitting there for quite some time... like a year.

Like I said the big end of the rod is 'within spec' (within 0.008mm) with no bearing shells and the bolts torqued up to spec - measured in 4 different points, each 45 deg from the previous. I'm not sure if they close-honed the rod as they're brand new items, but it's worth a measure either way!

Haven't measured with the bearing in yet.

It almost seems as if the cap for the rod was put on backwards or something - but I can't remember which way around it was before i took it out, of course..

I also found another bearing with a tiny spec of foreign material embedded in it, along with a bit of a scratch - as if a tiny bit of a burr had got caught in there

I'll definately double check all the clearances with plasti-gauge, but the problem is that it only measures the clearance in one spot - so while the clearance on 'top' of the big end might be spot on, it might have a tight spot a little off that point. - So I'll measure all round the journals etc and then confirm the measurements with plasti-gauge once they're all determined to be ok.

for now I guess I'll wait for the crank to arrive to do more measuring, and then it looks like I'll be getting another set of bearings.

I'm glad I pulled the thing apart now, though

I assume this kind of bearing wear indicates metal-metal contact?

Yes, that indicates insufficient clearance.
As far as measuring bearing crush goes, if you've clocked the closed big ends and the crank journal, then the plastigauge should be a good indicator of what bearing crush you have, as it should be concentric around the journal, if it isn't, the inefficiency points to your bearing shell.

[rcnugget]

I used to be an engine reconditioner a few years ago.....

the caps should have dots on them to relocate around the right way, I understand this is a new crank and not a reco item?

if you have no warranty I would suggest getting a crank grind and use OS bearings to clear it all up

I think you would have a fair case for getting the work done for free or replaced if they did not use an assembly lube on the bearings

[VN_Luke]

plastigauge should be a good indicator of what bearing crush you have. it should be concentric around the journal, if it isn't, the inefficiency points to your bearing shell.

Which is also possible - I'll get some measurements up with the bearing in and torqued up. I will also measure it all up with the conrod cap bolted on backwards, to see if it goes wonky around where the wear is.

I want to find the actual cause of the issue. It seems that it has to be in the rod or bearings right? (whether because the cap was bolted on backwards, poor machining, faulty bearing, or some crap caught between the two shells ruining the bearing crush?) I would imagine if the crank was bent, i'd see similar wear on more than just these bearings? - and if the crank was 'out of round' by a fair amount on that journal, the bearing would be worn all around, rather than have a 'tight spot'?

Once I know the cause of the issue, I'll be able to sleep better - hopefully it is as simple as mis-assembly

And once I'm happy with how everything measures up and 'dummy assemble' it for the first time, I'll definately break out the plasti-gauge to verify all clerances.

the caps should have dots on them to relocate around the right way, I understand this is a new crank and not a reco item?

The rods are numbered from the rod manufacturer, the 'tab' for the bearing shell is on the same side as the number. Both numbers & tangs should be on the same side - right?

The crank is the original crank from this motor - was in pretty good shape when removed and only got a linish/polish as far as I know. All the bearings are std size + .001"

The rods are brand new H-beam forged items.

if you have no warranty I would suggest getting a crank grind and use OS bearings to clear it all up

Yep definitely if it turns out the journals are out of spec.

I think you would have a fair case for getting the work done for free or replaced if they did not use an assembly lube on the bearings

they did use an assembly lube - and plenty of it.

They don't offer a warranty due to the 'nature of the application' - that's why i wanted to pull everything down and triple check all clearances etc. If it spins a bearing or throws a rod, I have noone to blame but myself.

It seems that noone wants to warranty an engine built for a non-standard application The builder blames the tuner and visa-versa.

Now another question -
is it common practise to lube up the mains 'housings' in the block, and then put the bearing shell in? or do people just put the bearing in with no oil or anything underneath it?

And can anyone recommend an assembly lube brand/type?

Thanks for the help so far!

[VT-565]

And can anyone recommend an assembly lube brand/type?

Any good known brand. I use moly-cote which is as good as anything out there. As for anything under the bearing shells in the caps etc. use a smear of the engine oil you're going to run or just a good clean mineral oil. Never dry.

If the rods are brand new, then i would be checking them as you said, if they have close honed them with the cap the wrong way, i'd be straight onto them for a refund cause that is just crazy.

While you're there, id get the crank in a lathe and throw a dial on the journals to check it out. One would presume they would have checked for this when they cleaned it up, but since you're going to the trouble, i'd be doing all i can.

Sounds like you have a bit of a mission ahead of you.

[VN_Luke]

Thanks heaps again for the advice.

I've measured the rods, with the caps on the correct way around, and the one in question came out:

A: 52.990mm
B: 52.990mm
C: 52.985mm
D: 52.990mm

(refer to picture for measurement points)

All the other rods were very similar with their measurements.

So seems if they did close hone them, they did it with the cap the right way around.

when i get home will measure where things sit with the cap on backwards and hopefully that will be it

Definitely a big mission ahead of me - but I think with the right amount of care and learning, and double checking - it should be possible!
So far I think I'm already one up on the original assembly lol.

[VT-565]

Can I ask how you are using your bore gauges? Are you running an external mic over them or relying on the gauge itself? All my guys use an external mic on the bore gauge as it is far more accurate and eliminates errors over jobs.

Also, you say the one in question came out nearly two thou out on one dimension, what about the rest of the rods? are they good or the same as this one?

[VN_Luke]

I measured and re-measured since the original post just to verify - the bore gauge is accurate to 0.01mm, so the 0.005 readings are from when the needle is between two numbers (rounded to the nearest whole or half).

Specs for out of round for the big end journal on the crank is 0.008 (that's where the 0.008 came from - but since measuring and remeasuring, that changed to 0.005 on the rod in question - due to rounding.)

sizes are as follows: - note that the bearings on all the other big ends look brand new - although one has a tiny scratch and a tiny spec of foreign material in there

all measurements in mm.
Rod 1:
A: 52.990
B: 52.995
C: 52.985
D: 52.990

Rod 2:
A: 52.985
B: 52.990
C: 52.990
D: 52.990


Rod 3:
A: 52.980
B: 52.985
C: 52.980
D: 52.990

Rod 4:
A: 52.985
B: 52.990
C: 52.990
D: 52.990

Rod 5:
A: 52.990
B: 52.990
C: 52.985
D: 52.990


Rod 6:
A: 52.990
B: 52.990
C: 52.990
D: 52.995


I was setting the mic to 53.000mm, then putting the bore gauge in there and adjusted such that it could measure a bit 'below' 53mm

after this adjustment, I 'walked' the bore gauge in the mic to find the shortest distance and 'zeroed' the bore gauge. (moved the dial face until the needle read 0) - I repeated this a few times till i was consistently able to get 0 on the gauge at the shortest distance.

then I stuck the bore gauge in the big ends (and walked till i got the 'lowest' reading - shortest distance) read the reading on the 'negative' side of 0, and subtracted from 53mm

I 're-zeroed' the bore gauge after measuring every single rod - sometimes it would be up to 0.005 out.

[VT-565]

There are some pretty average dimensions there, what brand of rod are they??

But Ok,

Here's how we do it;

Use the bore gauge as a transfer of dimensions only, take no notice of what it reads to. Put the bore gauge in and find a firm fit, then measure that with your mic, this will give you the easiest measurements to keep track of and they will all line up with each other.

Also, check this link out, will give you a bit more insight.

Engine Crankshaft Bearings

[VN_Luke]

Cheers for the link - read through all that last night (along with a whole bunch of other pages about bearing failure and construction) - getting there.

The rods are these ones;
SPOOL RB30 CONRODS - Spool Imports - Japanese Performance Parts

Perhaps my measuring is up the crapper. - the dial bore gauge I'm using doesn't have a 'lock' on it to be able to transfer dimensions and try your method.

I will source a set of lockable telescopic bore gauges and re-measure.

I presume that this means that the rod big ends should be basically 100% spot on same size all round?

.01 millimeters = 0.0004"
.005 millimeters = 0.0002"

Site says they should be +/- 0.0001" (so potential difference of 0.0002" in measurements?) - I suppose the difference is within the error margin for the equipment I'm using (bore gauge dial is to 0.01mm)

oh well, more learnt! - I'll remeasure and report back

[Pub247]

To me the rods seem fine there is less than 1 thou ovality across all measurements. Were they measure with the bearings in and correct torque?
Did the rod bolts/studs come with the rods or did you buy seperate?

You should use bearing blue and trial fit your bearings (correct torque) this will show that they seat correctly and evenly in the rod. Maybe that bearing wasnt sitting properly.
Basically what VT-565 has said is pretty much spot on.
The fault could be in the crank as it hasn't been ground its all hard to tell over the net.

Me personally the way i would have gone about it is to use the next size bearing (+10 in your case) inserted all your bearings torqued up and measured all the sizes. Work out what clearance you want to run i'd use 1.5-2 thou and get your crank ground to those specs. IMO this is the best way to go about as your size is going to be spot on. It's better than getting a 10/10 grind as you dont know where they measured from and you can end up with tight spots or too big of clearance.
Dandy Rebores is usually pretty good. If you need to get machining done again and your not happy with them i recommend Dandy engines The guys there are good at what they do and build some tough motors

[Pub247]

1 thou = .0254 of a millimeter or 1mm= 40thou

[VT-565]

Site says they should be +/- 0.0001" (so potential difference of 0.0002" in measurements?) - I suppose the difference is within the error margin for the equipment I'm using (bore gauge dial is to 0.01mm)

With tolerances, they usually list a measurement i.e. 1" +/- 0.001", so anything from 1.001" or 0.999" is acceptable.

Good thinking with the measring, get that spot on first then you know where to go from there. Another option is to box up the gear and head to an engineering shop and have a look at it with them.

[VN_Luke]

The thing is - this should have already all been done and spot on!

About a year ago, I gave a shop (one of the two recommended above ) the block, crank, rods, pistons, and asked if there are any operations I should do to the motor while everything is out to make it better for a performance application.. I was told no, and that was fine.

So I asked them to go ahead and measure all the parts I gave them, and machine block/crank etc - then select bearings to suit so everything is within spec ready to bolt together.

I got the engine back assembled (I wanted to assemble it myself, but figured bonus!)

After a fair bit of reading etc, it was determined that the crank 'nose' where the oil pump drive is needed to be modified with a special collar to widen the bits that drive the oil pump, to avoid failure of the drive setup at high RPM.

so out came the crank, and went to another shop to get machined (as the original shop said they "don't do modifications") - currently I'm waiting for the crank to come back from this modification ONLY (all other machine work and balancing had already been done, prior to the original assembly!)

I figured since the crank was already out, I should double check all the measurements etc as I read around and the general consensus is to always double check.

In theory, the crank should have been ground if it needed it, all bearings selected accordingly to get sensible 'within spec' clearances etc. - In practice, I tore down the motor and found a worn bearing

Just want to find whether the cause is improper measuring/grinding/machine work or assembly by the shop that built the motor!

so my plan of action is:

1) re-measure everything to better accuracy
2) if everything in step 1 is according to spec, re-measure the big-end in question with the cap on backwards to see if it would explain the wear (i highly suspect this!)
3) wait for crank to finish being modified
4) measure crank journals and work out clearances to see if the rest of them are fine, or if the crank needs to be ground again and run thicker bearings.

Overall, I have a much better idea of where I currently stand and what my options are for fixing the problem. Cheers again for the input from everyone! It's amazing how much there is to learn! - every thing that I look into turns out to be a few nights worth of learning - but no complaints here!

I'll let you know how the measuring goes

[VT-565]

2) if everything in step 1 is according to spec, re-measure the big-end in question with the cap on backwards to see if it would explain the wear (i highly suspect this!)

I'm not sure if you'll find anything there, apparently, the rods are dowelled.
But also depends on the type of dowels used, if they are the sleeve type, then it is still worth a check, but if they are offset dowelled, then technically, the cap can only go on one way.

Just another thought, you said the bearings were +0.001", what do the crank journals measure up at? there may be an indescrepancy there.
Let us know what you find
Cheers

Nick

[Pub247]

Yep that was my though about the crank aswell some of the journals may not be perfect as it never got ground only linished.
If what you say about the cap being on the wrong way then its a good chance that will be your problem. I doubt the dowels would be offset as it would imbalance the if one bolts were a little further out than the other. Looking at the picture of the rods suggest the tangs are on the same side (which they should be) so if you pulled it off and it was on the oppisote then you'll be right.

Anyhow i don't think dandy rebores would have a problem fixing it (and for nothing) if it turns out to be something else or something they done. The motor has never be run and you have evidence to suggest that something was wrong.

[VN_Luke]

yep the dowels are sleeves around where the bolt goes through, and the cap can be bolted on backwards pretty easily.

Anyhow i don't think dandy rebores would have a problem fixing it (and for nothing) if it turns out to be something else or something they done. The motor has never be run and you have evidence to suggest that something was wrong.

yeah hopefully that's the case if machining is required etc. - although it has been a year - and whether I still have the receipt or not is another matter

[VN_Luke]

Ok did some measurements of that rod with the bearing in place, and rod cap on the correct way around: (using the telescopic gauge now)

I've ignored measurement 'C' as it was jumping between the two bearing halves and wasn't really measurable.

but

Cap correct way around:

A: 50.03mm
B: 50.04mm
D: 50.03mm

Cap the wrong way around:

A:50.03
B:49.94
D:50.145

It just so happens that both bearing shells are 'worn/shiny' in exactly the same spot that measurement B is made. and when the cap is backwards, there is wear on both caps, directly opposite each other at this point.

- also the edges of the bearings don't seem to quite meet happily where the cap goes onto the rod, and you can see spots of 'no wear' on the bearing that's a little 'lower' of the two where they meet, followed by excessive wear wear about 10mm from that point, if that makes any sense. - wear all consistent with a crank spinning, and there being a 'pinch/tight spot'

So it does in fact seem that they have bolted a cap on the wrong way - the numbering on them is very faint so I can see how the mistake could have been made!

very happy to have found (hopefully ) the cause.

I guess after I've finished measuring everything else etc I'll have a chat to the blokes and see what they say, and whether they're happy to throw me a few bearings if everything else measures up nicely.

one big question - how damaging is it to the bearings to be measuring them? I seem to be 'marking' them with the measuring equipment an awful lot!

(pic attached, for your viewing pleasure) - one from each direction with cap bolted on wrong way around. - also note the craptonne of 'marks' from measuring - i can't feel them at all with my nail or anything, but am I being too 'rough' and these render the bearings useless? or will dissapear soon enough anyway?

[azkwazere]

This is a really cool thread.. i had no idea the measurements were so complicated!!!

Its good to see you've sorted it out though... Guess rebuilding my engine will be slightly harder than i thought

aZk.

[Reaper]

one big question - how damaging is it to the bearings to be measuring them? I seem to be 'marking' them with the measuring equipment an awful lot!

(pic attached, for your viewing pleasure) - one from each direction with cap bolted on wrong way around. - also note the craptonne of 'marks' from measuring - i can't feel them at all with my nail or anything, but am I being too 'rough' and these render the bearings useless? or will dissapear soon enough anyway?

It's difficult to tell from your pics. When you say "marking them", are you scoring the metal or is it just the assy oil/coating that you have removed? Either way, I'd give them a really good clean, check if they are scorred at all and then re-apply the assy oil before putting them together. If there is any scoring of the metal at all I would probably replace the bearing.

Reaper

[VT-565]

I'd say you are marking the white metal, but it may not be detrimental. In all honesty, i'd be putting new bearings through anyway. Those marks you see are a 'disruption' in the finish of the bearing metal, when you look at it on a microscopic level, is full of 'peaks and valleys', not as smooth as some may believe. So, believe it or not, you are flattening these 'peaks' off with the rounded ends of the bore gauge, which gives a different appearance. These 'peaks' would get disrupted after a few hundred engine revolutions anyway, hence the term 'loosening' up.