swerve-driver

Howdy-
I recently purchased a balanced 383 rotating assembly from Competition Products in Oshkosh, WI. Nothing fancy, just a cast crank with reconditioned GM rods and ARP hardware, HU pistons, rings bearings and a balancer.

As I was assembling the shortblock, I noticed something weird with 2 of the end caps. Essentially, two of the end caps had ~two~ grooves cut in them (to hold the bearing in place) where-as all the others had only the required ~one~. The photo should show what I am talking about.
The significance of the second notch is that it will -not- hold the "tang" of the rod-side bearing in place, which, I believe is practically begging for a spun rod-bearing situation. The un-necessary second notch essentially removes about 1/2 to 1/3 of the rod bearing tang-holding capability of the cap.
I called CP and, after an initial denial and assurance that it was normal, they agreed to work something out.

My questions are: Have you ever seen a rod cap with more than one groove in it? Is this normal? Do you believe this would result in a spun rod bearing eventually?
I plan to return both piston-rod-cap asseblies to CP for replacement. Is there any thing I should be on the look out for upon their return (besides good end caps).

Any replies/info is appreciated-
S-D

swerve-driver

One more photo to provide a little more detail

chevymad

Havent seen that, but if you replace 2 rod/piston assemblies you'll no longer have a balanced assembly either.

ede

i don't see how the cap with 2 notches wouldn't still engage the tab on the bearing same as the single notch cap.

swerve-driver

The cap will hold the cap-side bearing just fine. What I am getting at is that the cap will not have the required meat to hold the rod-side bearing since the second groove in the cap lines up with the bearing tab groove on the rod.
Anyone else seen/dealt with this?
Thanks,
S-D

swerve-driver

Just a matter of ensuring the replacements weigh the same as the originals.
S-D

RB83L69

The problem is, the tang on the other half of the bearing lines up with the extra notch that you can see in the pic; so the upper half tang is very near to having nothing at all to hold it in place.

It is definitely not normal. I have no clue why those are there. I don't think I've ever seen that. I wouldn't want it either.

As long as they provide 2 rods with the same big / small end weights and all that (to match the rest of your set), the balance will be preserved.

Brent

iTrader: (1)

The tangs on the bearing are for locating the bearing side to side in the rod only.

The bearing crush is what prevents the bearing from spinning.

swerve-driver

Thanks for the additional input. I was unaware the tangs are for alignment only- I had always assumed they were for keeping the bearing from spinning.
I am still planning to return them. I suppose it will be the difference between wondering if the bearing will spin or if they actually sent me replacement rods with the same big/small end weights as the originals.

I became suspicious when I was assured by CP that this was "normal" and that it wouldn't cause me any problems. When I asked for something in writing, that changed to "send them back if you're not happy".
They just look inherently wrong to me so I'll take my chances with replacement rod/caps being balanced.

Thanks again-
S-D

AJ_92RS

Not trying to say you shouldn't have done what you did, but a simple matter of paying attention to which way the rod is facing would have prevented the bearing from spinning. After all, the crankshaft only spins one way.

I guess that would depend on if you bought the kit with the pistons pressed on. If so, you'd have no choice but to get replacements or pay a machine shop to swap out the pistons making sure the culprit was facing the right way.

Regardless, good luck with it.

swerve-driver

All Rod/piston were assembled correctly by CP.
The rod bearing did not spin.
Strictly a preventative measure on my part.
Thanks,
S-D

AJ_92RS

I didn't say it did spin. I said it could be done propery (or if it would be done properly) it would not (as in hypothetically) spin.

And "correctly" is a relative term.

Regardless, I don't blame you at all for being concerned. There are just other avenues that you could take. But that's cool. I'm sure you didn't pay for that, you paid for stuff to be ready so you didn't have to be concerned.

swerve-driver

CP found me new rod/caps with the same (or at least very close) big and small end weights as the originals. They are on their way back. CP gave me no grief, they recieved the returns and replaced them- no additional troubles.

Do any of you guys have input as to the flywheel requirement for this rotating assembly and a T56 LT1?

If you do an can offer any insight, I'd appreciated.

Here is the link to my post on the topic:
https://www.thirdgen.org/techbb2/sho...hreadid=232343

Gracias-
S-D

RB83L69

Your other post shows a 400 balancer. So you have an externally balanced assembly.

No such flywheel exists, as a 400-balanced T-56 flywheel. You'll have to make your own.

I'd suggest getting a regular LT1 T-56 flywheel, and have it "unbalanced" to match the stock 400 spec, by simply drilling around the edge; and hope like hell that that's how they left your crank and rods balanaced. You might want to ask the vendor exactly what they did. Since, after all, there's no such thing as a 1-piece RMS 400, then by definition there's also no such thing as "stock 400 unbalance" for that thing.

radiateu2

I cant see how CP can just send you new rod caps...the rods and caps need to be resized...i bet the caps and rods wont match up perfectly when you get them...i think I would have sent the rods and caps back for new rods and caps sized....good luck though

onebinky

iTrader: (1)

Thats what he did

"CP found me new rod/caps with the same (or at least very close) big and small end weights as the originals."