krooser

When I pulled down the 330 I'm working on I had the old rod bearings literally fall out of the rods... the bearings are egg shaped.

I read somewhere that this is a common deal with the Olds engine.... anybody?

rustyroger

Years ago I worked in an engine shop (in the UK), I noticed that some engines often had rod bearings fall out. Rootes and vauxhall engines were the worst one for this.
The shop always resized all rods anyway so it wasn't a problem. However if someone brought a crankshaft in to be reground we would refuse unless they also brought the rods in for checking. Often they thought we were trying to rip them off for unnecessary work, but they normally understood when we explained why and asked them if the bearing fell off when they took the rods out.

Roger.

Oldsmaniac

On a high mileage engine it is not uncommon for the bearing shells to drop out of the rod and cap when they are removed from the crank. They are not a press fit when installing. Always have the big end of the rods trued when rebuilding.

krooser

I doubt this is a high mileage engine. It's been apart before and the odometer was at 58,000 or so I was told. The car was blasted in the rear and parted out.

As I mentioned, I read this recently that it is common on an Olds. I will redo the rods anyway so I'm not concerned but I just like to if this may be related to the oiling problems some have seen on certain rod journals.

Octania

I have seen this phenomenon a few times, out of several dozen Olds V8 engine dismantlings. Maybe 5% I would estimate. Generally, there is a worn spot in the middle of the bearing, and the cap half is less likely to be loose. I would attribute this to abuse- this deformation is what one might expect from e.g. a severe hit to the piston.

That might come from detonation, which is common when using low octane fuel in a high compression engine, without altering the spark timing to suit. Or, perhaps revving the engine far past its normal range of rpm, while nice and warm. Flinging the pistons at high speed, smacking the rings into any ridge that may exist at the top of ring travel. Both are things likely to happen when a youngster gets an old engine.

Many of the engines I have torn down were high compression engines from pre-1971, which died in the 1980's to 1990's....

So, I will vote for abuse by way of detonation and/or idiocy as the leading cause of this uncommon but by no means rare condition.

Since I was typically not using the rods right away, they were not checked for roundness or lack thereof.

Run to Rund

I have seen this when the rod big end was out of round. Olds rods are fairly soft; I strongly recommend re-sizing the rods whenever building an engine, or using good aftermarket rods.

VORTECPRO

I allways oval hone Olds rods, that puts an end to rod problems assuming everything else is correct.

cutlassefi

Please explain how and why you do that.

VORTECPRO

Large diameter crank pins combined with heavy pistons tend to pull the parting lines in at high RPM at TDC. Extra clearence at the parting lines help prevent a bearing touchdown, its very effective, infact it helped a friend of mine set a record in Super Stock that was unheard of for its time.

380 Racer

Doesn't sound kosher to me .

cutlassefi

I understand the principle, but I'll ask this one more time. How do you recon a rod that's very round to begin with, to have extra "clearance" at the parting line?
And for the record, if a rod is that soft and pinching that badly at the parting line then you have other problems. For all, Clevite P series bearings are eccentric, meaning they already have the "extra" clearance at the parting line built in to them. H series are more round and have very little difference vertically vs horizontally.
Sometimes an imbalance will have an effect on this as well but that is typically noticed vertically, not horizontally.

Again I'm only going to ask this once. If you cannot or do not answer it then I will assume its total bs like most of the rest of your posts. And for everyones' benefit how about the name of your Super stock "friend" and the details outlining how this one change helped him win the title.

I'm asking 1 time dude, that's it.

Thank you in advance.

VORTECPRO

I would rather not get into how I do it. Maybe this isnt for everybody, but works great for me when using production rods with heavy pistons that you want to turn RPM with. I would say this: David Reher sure had his eyes opened up to this machining operation! Kip Martins son came up with this technique, it was the only way they could keep the rods in their 352FE Record shattering Galaxy 500 Super Stock, of course back then you had to use stock rods in Super Stock.

380 Racer

Isn't this known as bearing crush?

krooser

Aren't you guys glad I showed up on this board to pose these weird questions?

MX442

I hear that if you spin them over 6000 rpm you'll get the same effect.

krooser

The Ford flatheads from '37 (?) to '48 used a floating bearing that spun inside the rods... no tangs to limit their movement. Most guys change that when modifying those engines.

cutlassefi

Just like I thought, no answer, more bullshyt.

Were you a politician in another life? Just curious.

VORTECPRO

No, just a engine machiner and builder.LOL

cutlassefi

That would be engine machinist, not machiner.

That kinda puts it all in perspective doesn't it?

VORTECPRO

Maker sure you get a "machiner" that can oval hone those Olds rods so you dont have any more rod failures.

380 Racer

When I told my engine builder about Reher having his eyes opened......he said "right" and LHAO. Old school trick.

VORTECPRO

Im sure David Reher had his eyes opened more than a few times by Darin and Brad Morgan, Kip Martins step sons............

archeryshooter

Everyone I have driven seems to do that, Hmmmmmm I like that sound though

matt69olds

I have seen it many times, recondition the rod, use good rod bolts and machine the crank for a little extra clearance. Make sure the rod side clearance is on the high side of factory spec. I have been told its due to heat, open up the bearing and side clearance so the oil can escape and draw the heat out of the bearing. This has worked well for me.

archeryshooter

I have seen were this works great for some but others claim low rpm cruzing can pound the oil out of extra clearance and beat the bearings up also but if you run the rpms higher all the time they are fine. I had one last only 5000 miles that was built loose its hammering now and it had the rods resized with bigger bolts and balanced. To bad because I had over 100'000 miles with stock specs and still was running fine and i didnt baby it when I had it rebuilt they built it loose and it failed

HWYSTR455

Just went through this, as a matter of fact, still am. When the bearings fall out of the top half (not the cap), usually it's caused by det. Other causes are from improperly sized big ends, loss of oil wedge, line bore out of whack, bearings with an edge/lip from poor manufacturing or QA, and taper.

To touch on that a little more, rod big end taper, bell mouth, or whatever you want to call it is common, and it's due to the way the big end is finished. If you look at the pattern of wear across the bearing surface, you will see dark lines, and that's from tamper/bell mouth. (see attached) And no, this rod bearing did not suffer from det, even though the top half of the shell is showing copper. It lost oil wedge due to taper/bell mouth.

When you mic a big end on a rod, make sure to take measurements in several areas across the surface, not just in the middle.

And it's true, there are some instances where you machine the big end slightly 'out of round', so when under load, it 'straightens' out. When you machine a big end to the small end of the range of tolerance, it's wider at the parting line, which in some cases is desireable. In some cases, as pointed out, it's better to go to the large end of the tolerance, so the big end is more 'round'.

.

coldwar

Detonation AND/OR pre-ignition. The other tip off the worn spot at the rod beam point. The old timers phrase was '....pounding the rods out of it....'. Rod bearings, that is, then rods after bearing fails. Engines on fuel or aftermarket rods meant for fuel racing generally have the rod bearings pinned to slow the tendency to spin with the explosive burning and application of down force not unlike pre or det. These days most everyone resizes the big end anyway but not always in former years.

CANADIANOLDS

i dont know if i should laugh or cry i think ill cry cuz its saturday

kirkwoodken

What vortecpro says. Typically, you take a round big end, put some feeler gages or shim stock between the cap and the rod, usually around .006" thick, but it may vary, and hone the holes round again. That gives an oval big end hole, but at high RPM when the lower end of the rod stretches, the side of the bearing does not cut off the oil film. This isn't hokey science. Normal bearings are oval at the sides. They are made that way. Increasing the oval just takes up where the designers left off, not allowing enough ovality for the extreme RPM and loading of race engines. You don't need to do this on your daily driver.

Of course, you have to remove material from the mating surfaces so the hole can be enlarged.

Did I get close enough v-pro?

When the bearing shells fall out, it is usually from detonation/pinging.

I'll bet even DR has learned some stuff from other people. Everybody knows something you and I don't. I try to approach everyone with that attitude. Much easier to learn stuff that way.

holben

Beautiful car!

kirkwoodken

Oil flow from the bearing is determined solely by crank to bearing clearance. Grinding the sides of the rod has nothing to do with oil flow. Old wives tale like more overlap bleeds off compression.
However, if there is NO clearance between rods, they will heat up.