Boruskarloff

iTrader: (1)

Edit***** gave wrong measurement's for bearing bore size so I corrected it***

Came across a somewhat puzzling situation here on a L33 stock bottom end build. 97k on motor, turned over really nice and was said to run. All the bearings look great. Tore it down to clean everything up.

Upon measuring the rod big end, I'm finding that I'm getting .001-.0015 out of round, almost as if I had put arp bolts in but I am using stock reused rod bolts.

I tried the 15lbft then 75 degrees and also the 15lbft then 85 degrees; same measurements. I zeroed out the bore gauge at the 2.2247 and get 2.2237 (.001 tighter) at verticle and 2.225 closer to the parting line. Showing that the rod is out of round by.0013".

Seems odd that this is the case but just seeing if anyone went this in depth with there stock rebuild??

Also makes me wonder how Katech says you don't have to resize rods with their bolts if this is happening with stock used bolts . Guess I'll put some bolts in since I gotta resize these anyways.








-Travis

1FastBrick

iTrader: (16)

The factory rods are hit and miss.

I have seen them be within spec on some set's while some rods would be close to perfect while other rods from the same engine will be just on the edge of out of spec.

Also, I had my machinist checked both ARP and Katech. He states he has seen no difference in roundness distortion from stock to aftermarket bolts.

Prorac1

iTrader: (4)

When I put ARP rod bolts in my stock LY6 connecting rods we had some interesting findings.

We took the rods to our machine shop to swap the rod bolts and check the big end. Heres what we found.

The big end was perfectly round, but measured slightly bigger than stock. (I don't remember the exact number, but it was slightly over spec from what he said). We ended up overboring the big end and using the .002 oversized rod bearing.

The machine shop said that it could go either way. Mine would probably have been fine for many years, but the guy whos ended up to tight would not.

That was my findings. Eric L

Boruskarloff

iTrader: (1)

Ok thanks for the input...well all the rods on this motor are out of round, but all are almost exactly .001" out of round (bigger at the parting line).

I am a machinist by trade and run a mechanic shop out of my home shop. My engine machine guy is retiring so I'm working with him trying to get all his secrets before he goes, and maybe purchase the business.

Anyways, this is the first set of stock LS (thicker/later style) rods either of us have checked.

Seems odd they are all out of round the same amount and in the same type of way that better clamping bolts would do to a rod.

The book shows out of round production/service at: .00015-.0003

Guess it goes to show you that the guys that just slap these things back together without checking anything are really rolling the dice. No offense to anyone

1FastBrick

iTrader: (16)

You are correct. Personally I check everything, including the balance, even on a stock rebuild.

KCS

iTrader: (20)

Take the damn bearing out.

KCS

iTrader: (20)

I had a similar experience in my 6.2L with the ARP 2000 bolts. The housing bore grew at the 12 and 6 o'clock position, but it was within tolerance. I just ended up using a regular ACL 663H bearing.

However, in my 6.0L, the housing bore is about .0005" over the tolerance, so I'm resizing and going to use the .002" oversized bearing.

warriorpluto

iTrader: (2)

I'm just learning about this. So if I tear my engine down and reuse the stock rods I have to get them resized? I can't just install arp bolts in and put it back together?

KCS

iTrader: (20)

No and no. You don't necessarily have to have them resized, but you shouldn't just throw it back together either. If you use an aftermarket rod bolt, you should at least have the big end housing bore checked for size and roundness. Otherwise, you're taking a gamble over $100 bolts.

JustinEntropyRad

Any cred to the ARP torque levels being higher(often) than OEM potentially causing the elongation?

KCS

iTrader: (20)

Absolutely. Search this forum, it's been discussed, debated, and small countries have gone to war over the topic.

dr_whigham

iTrader: (49)

Sheer curiosity here:

So what happens if you torque the ARPs to "GMs" specs? Any distortion? Too loose to hold?

KCS

iTrader: (20)

I've never tried and I have no idea really. Since ARP has a torque or a stretch value and GM just has an angle value, it's really just going to be a WAG. If the GM bolt has just as much stretch as an ARP bolt of the same size, the ARP is still going to clamp harder since it's a higher tensile bolt.

Next chance I get, I may go ahead and measure the stretch of a stock GM rod bolt and compare it to the ARP 8740 and ARP 2000 bolts.

A.R. Shale Targa

iTrader: (2)

I talked to Rich at great length about your situation the other day; as my LS rotating assembly is also down there (Mick's Auto) with the Katech bolts and new pistons.
It really sux that he's selling off his equipment and getting screwed around a bunch by the freaks that he's dealing with. After fifty plus years of machining I just hate to see it go like that. Like yourself I just wish I could spend a few days learning his crank grinding as he and that old *** machine truly put out some artwork like cranks.
I have a LS3 rod that had spun a bearing and Rich and I are gonna hook up early next week as I'm still on vacation right now. He's gonna just use it to practice the oversizing +.002" and then check the factory bolt repeatability.
It's the perfect practice rod as it was not blackened or overheated but rather came from a 540 RWHP Grand Sport Vette that my retarded buddy decided to do a 3 minute 7 grand burnout with and the coated bearing finally said "uncle"...LOL
Sounds like your L33 should make some steam with that snail shaped muffler you're planning for it.......
Rich will get it figured out...he's pretty bright; for an old fart.

Boruskarloff

iTrader: (1)

Rich is awesome and very thorough! Learning a lot from him.

I will report back here with finding of our experiment.

Thanks again Targa.

KCS

iTrader: (20)

I guess I should clarify this.

The housing bore of the stock rod is about 2.2242". If you have a bore gauge set to 2.0999" and you're getting .0015" clearance, you are not measuring the housing bore, you are measuring the bearing ID.

A bearing is designed to have more clearance at the parting line than at the 12 and 6 o'clock position. What you are seeing is completely normal because you are not measuring an out of round housing bore, you are measuring a normal bearing.

Boruskarloff

iTrader: (1)

Yea this was my fault... I should be the one clarifying. I used the bearing clearance reference in my original post.

I realize the rod with bearings should have a bigger tolerance at the parting line as the bearings are designed with that eccentricity built in to promote oiling. In any case that is good to point out to me or anyone reading this who may not know this.

Anyway all of my L33 5.3 rods are out of round measuring the rod bore without bearings.

So we experimented with different torque angles with no difference in roundness on my rods.

Targa gave us the spun bearing rod today so we cleaned it up torqued 15ftlb the 85 degrees. Measured it to find it was out of round naturally. We honed it round and it came out great where it still can use a standard bearing since the bore was right at 2.225 (std is 2.224-2.225).

We then disassembled it, cleaned it, and reassembled using 15ftlb and 85 degrees. This yeilded a consistant measurement and repeatability using stock "reused" bolts. So looks like even with stock bolts going back in the rods should be at least checked, because it seems that somehting is happening with the stock rod bolts and the clamping force applied is changed from when they are first installed to when the are being reused. This may not be the case for all rods but was definitely the case in 9 of 9 rods (second gen rods) the we have.

KCS

iTrader: (20)

FYI, I just ordered ACL Race bearings for .002" over rods, which are actually available in STD and X (.001" more clearance). These are the tri-metal steel backed bearings, narrowed even for large radius aftermarket cranks.

CB663HOS2-STD for STD size or CB663HXOS-STD for .001" more clearance.

Less than $95 shipped.

dr_whigham

iTrader: (49)

I wish you could tell at what point (what angle or torque value) the rod "starts" to become out of round.

As stated before, ARP takes a certain torque value.

If I could (flame suit on) I'd red loctite the rod bolts and torque them right to that point where they "want" to go out of round. That's pretty much what I was getting at earlier. I wish I knew the value to torque them to without distorting the bore. I'd red loctite them there at that point and let the engine eat.

Boruskarloff

iTrader: (1)

Red loctite, I do love that stuff and it has saved me in many situations.

In this case though, it's $48 at our shop to have the rods checked and honed true, and this way you get the repeatability of that stock reused bolt everytime you torque it up. Peace of mind there.

All my rods cleaned up within stock rod bore size, so I ordered clevite (or maybe sealed power? idk) standard A series.

also ordered turbo and cam package from liljon today.