360 crank knurling?

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QUINN FORBES

QUINN FORBES

Greendemon
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Anybody hear of a small block not having the crank knurled at the rear main seal?
I have a virgin crate motor ( P4876908 ) I have had for over 15 years and I decided to tear down and inspect before assembly and install.
Mic shows the crank is standard size ( not turned ).Upon removing the main caps I noticed the crank has no knurling at the seal. I have never seen a small block without knurling, This seems to me It would leak without the knurling and not forcing the oil back into the crankcase.
Any thoughts?

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That is a 5.9 Magnum deal. They leak less. It is a good thing. Knurling was originally for rope seals.
Some say aftermarket cranks have excessive knurling and leak more.
 
What is the casting number of the block, casting number of the crankshaft, and casting date of the block?

If I remember correctly, that part number was used while they were building these off of a Magnum short block. Some were made to LA balance weight and some Magnum balance weight, part number dependent.
 
I thought 1990 blocks were the roller Motors with the LA heads not magnums.

By the way you're better off without the knurl marks all they do is make that Rubber seal leak.
 
Is it a hydraulic roller cam?
I thought they put hydraulic flat tappet cams in those short blocks.
 
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I have had rusted BB crankshafts welded and machined on the rear main seal surface. Zero leaks with a fel-pro stock rear main seal. The machine shop said it would be just fine, and it is.

so it’s more made up baloney
 
Interesting the cranks are the same but makes sense. I just hope the catalogues suggested balancer and flex plate are correct If the balance is different from magnum and LA.
 
The crank I checked first was from a 94 casting block.

I also have a Mopar short block one part number off from the one Quinn posted the question about. I will put the picture of the sticker below. Mine would be the lower compression version, his is higher compression version, but both are supposed to be balanced as LA engines. This also has the same crankshaft casting number.
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It may be possible Mopar’s vendor used whatever block they had, since it was going to be set up as an LA anyways.

Also wondering when they started offering that part number. Maybe his is much earlier than mine.

I do know both part numbers were still available in the 2002 Mopar catalog.
 
How about this? The roller Motors use the LA rods and pistons. The Magnums used different piston and Rods that were balanced different. But if they both use the same cranks that could be why the harmonic balancer and flexplate and converters are different.
 
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Yes. Cummins did some of the crate engine and short blocks and I think a shop here in Michigan did some. Maybe Arrow Racing Engines? I forget. Not sure who was first, if there was overlap at the same time, or if there was any more doing them.

Mine had a strand of metal from a wire wheel stuck under the head of one rod bolt. Took it apart and also found an extremely tight cam bearing. The bore was under size from spec from when it was originally built, but it was not fixed when they made it into a crate short block. That was fun.
 
Jadaharabi said:
How about this? The roller Motors use the LA rods and pistons. The Magnums used different piston and Rods that were balanced different. But if they both use the same cranks that could be why the harmonic balancer and flex plate converters are different.
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Not sure yet, but I suspect the casting number tells them which balance factor the crank has drilled into, and they are different. I will try to keep this short.

I have a 92 casting block. Bought damaged. A few broken rings. Came with Edelbrock aluminum heads so no idea which way it was originally set up, but suspect it was in a 93 model year truck, making it a Magnum.

I asked a local Mopar shop to balance it as an LA when I replaced the pistons to fix it. Supplied an LA version B&M flex plate. Put it all together as an LA and it vibrates. Figured out the difference between LA and Magnum converter weights and welded the difference into the flex plate cutout area on my converter as a test, still in the car. Vibration is fixed, gone. So that engine needed a Magnum flex plate.

My theory is they balance it to a Magnum factor based on the casting number, which I think it was the same casting crank and rods as the Magnum stuff I compared to.
 
Bobzilla said:
Not sure yet, but I suspect the casting number tells them which balance factor the crank has drilled into, and they are different. I will try to keep this short.

I have a 92 casting block. Bought damaged. A few broken rings. Came with Edelbrock aluminum heads so no idea which way it was originally set up, but suspect it was in a 93 model year truck, making it a Magnum.

I asked a local Mopar shop to balance it as an LA when I replaced the pistons to fix it. Supplied an LA version B&M flex plate. Put it all together as an LA and it vibrates. Figured out the difference between LA and Magnum converter weights and welded the difference into the flex plate cutout area on my converter as a test, still in the car. Vibration is fixed, gone. So that engine needed a Magnum flex plate.

My theory is they balance it to a Magnum factor based on the casting number, which I think it was the same casting crank and rods as the Magnum stuff I compared to.
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That is just screwed up. If you took them all the components to be balanced including the harmonic balancer and the flexplate how the hell would they screw up the balance?
Don't know if I'd be using those people again.
Who was it Hughes? You don't have to answer that. LOL
 
Back in the mid 80's I got a 440 crank from Hamburger and it had no knurling. That's all I say.
 
Jadaharabi said:
That is just screwed up. If you took them all the components to be balanced including the harmonic balancer and the flexplate how the hell would they screw up the balance?
Don't know if I'd be using those people again.
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I agree. And that was the first time I used them.

I can see how it happened though, if the casting number told them Magnum so they didn’t use my parts. But damn, tell me that so I know.
 
My bad experience with mopar performance short block was one main bearing bore was .003 larger than it was supposed to be and the middle two pistons each bank were out of the hole and all the outbound pistons were in the hole. Total pos. Should have known why it was discounted at $1100.00
 
Interesting again Jad!
So if the shop balanced your 92 as that year they must have used magnum specs hence the vibration.
If I understand that correctly.
Even though you asked them to balance as an LA… BRUTAL !!!
Well theres hope for me since this block hasn’t been run yet and assuming the flex plate I bought is correct for LA 360. I will be doing my homework on that for sure!
 
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