Main Cap Bolt washers?

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ZjStroker47
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Joined: March 10th, 2018, 7:18 pm
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Main Cap Bolt washers?

Post by ZjStroker47 »

Finalizing my parts while the block and rotating assembly are at the machine shop. And curious about the whole ARP washer situation with the main girdle. I can't for the life of me find a reason why it would be a bad idea to put a washer under the main Cap Bolt. There can't be enough of a strength sacrifice by the threads engaging .120" less in the hole. Plus, I like the piece of mind of having a moly washer between my main Cap Bolt and cap, especially when torqued with ARP lube.

So my question is: why does everybody use a 3/8"id washer under the girdle to space it instead using a 1/2"id washer under the main Cap Bolt? A set of 14 ARP washers are expensive to be used as a spacer. If ran under the main Cap Bolt it might
actually help something and space the girdle as wanted.
Russ Pottenger
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Re: Main Cap Bolt washers?

Post by Russ Pottenger »

I think you're running the risk of overthinking and reengineering a problem that doesn't exist.

For 99% of all the 4.0 stroker builds the factory OEM 1/2 13 bolt with full thread engagement works fine.

Whenever you deviate from this you the risk of changing the clamping force and bolt stretch. Even switching over to the ARP Molly assembly lube will alter the factory recommended main bolt torque spec.

In applications if I were to use a ARP 1/2 stud with a rolled 1/2 20 thread, because of the change in clamping force, I'd more than likely have to line bore the block.

I'd recommend just sticking to a .120 ground 3/8 washer.

Not to throw in a sales pitch : ) but I do offer an upgraded bushed 6.125 steel connecting rod with a cap that has a profiled strengthening rib rather than a big and clunky balance pad.


Russ
Russ Pottenger
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Re: Main Cap Bolt washers?

Post by Russ Pottenger »

[quote="Russ Pottenger"]I think you're running the risk of overthinking and reengineering a problem that doesn't exist.

For 99% of all the 4.0 stroker builds the factory OEM 1/2 13 bolt with full thread engagement works fine.

Whenever you deviate from this you the risk of changing the clamping force and bolt stretch. Even switching over to the ARP Molly assembly lube will alter the factory recommended main bolt torque spec.

In applications if I were to use a ARP 1/2 stud with a rolled 1/2 20 thread, because of the change in clamping force, I'd more than likely have to line bore the block.

I'd recommend just sticking to a .120 ground 3/8 washer.

Not to throw in a sales pitch : ) but I do offer an upgraded bushed 6.125 steel connecting rod with a cap that has a profiled strengthening rib rather than a big and clunky balance pad.


Russ
Bishop-Buehl Racing Engines
Russ Pottenger
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Posts: 889
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Vehicle Model: Cherokee

Re: Main Cap Bolt washers?

Post by Russ Pottenger »

I think you're running the risk of overthinking and reengineering a problem that doesn't exist.

For 99% of all the 4.0 stroker builds the factory OEM 1/2 13 bolt with full thread engagement works fine.

Whenever you deviate from this you the risk of changing the clamping force and bolt stretch. Even switching over to the ARP Molly assembly lube will alter the factory recommended main bolt torque spec.

In applications if I were to use a ARP 1/2 stud with a rolled 1/2 20 thread, because of the change in clamping force, I'd more than likely have to line bore the block.

I'd recommend just sticking to a .120 ground 3/8 washer.

Not to throw in a sales pitch : ) but I do offer an upgraded bushed 6.125 steel connecting rod with a cap that has a profiled strengthening rib rather than a big and clunky balance pad.


Russ
Bishop-Buehl Racing Engines[/quote]
Russ Pottenger
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Re: Main Cap Bolt washers?

Post by Russ Pottenger »

Apologies to the Moderator.
If you could clean up my double posting.

Thanks
ZjStroker47
Posts: 7
Joined: March 10th, 2018, 7:18 pm
Stroker Displacement: 4.7
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Re: Main Cap Bolt washers?

Post by ZjStroker47 »

Thanks Russ. I appreciate the response. You're probably right about the over thinking. I'm sitting here at home while my block is at the machine shop so all I'm doing is thinking. Waiting for thw call to pick it up. And I already own a set of scat forged rods thanks though!
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