Splayed main caps

[Twisted Steel Performance]

We are now stocking splayed main caps, 550.00 $

I have also made the decision these along with my Halo Girdle will be standard for customer builds, all the customer will pay for is the machining cost to install the caps...

@DieselAmateur you will like this

 

[SnowDrift]

Are the original outer two holes filled first, before machining the new ones?

 

[Twisted Steel Performance]

yes

 

[SnowDrift]

If this is not something you want to be included in this thread, please have it removed. I ran across this and it seemed a very good explanation of the subject topic. Even as I continue to consider it, this cleared up some things for me.

Cap It Off — The Main Things You Need to Know About Main Caps

We discuss the need for aftermarket main caps in high-performance engines and how to properly install them, along with the machining required.

www.enginelabs.com

 

[Twisted Steel Performance]

Sure post it, I'll get some side by side pics this weekend when I get Peter's motor apart.

 

[MrMarty51]

And with the new main caps, that would require line boring ?

 

[Will L.]

Yes

 

[Twisted Steel Performance]

Here are pics showing the difference between a stock cap and a splayed cap. @SnowDrift

The stock cap came out of @DieselAmateur 's block, another ding for GM's lack of caring is they went to smaller outer bolts but left the hole on the cap the same size as it was for the larger bolts, not something that a good company would have done....

 

[SnowDrift]

Nice! This paints a pretty good picture for those that are wondering.

 

[dbrannon79]

those bolts in the factory cap also look to be a wee bit short for the amount of stress they handle. one would wonder if the threaded hole is deeper in the block as to install slightly longer bolts without having to drill and tap more thread. I will examine my 6.2 more closely when that day comes.

 

[SnowDrift]

Good point. I can't help but think that more thread depth and better block penetration would help hold them still.

 

[Will L.]

Nopers. The more block you remove the weaker it is. Most all engineered tests show 6 threads hold all the load. A couple in specific applications a 7th holds a tiny amount, but pretty much everything you touch, 6 is it.

 

[dbrannon79]

the odd thing too that just came to mind. the smaller diameter outer bolt was probably a GM Band-Aid fix done to help alleviate the web cracking. from what I can tell the web cracks are more on the outer bolt hole areas of the block. I bet they thought "the less meat taken out, the less chance of a crack" apparently that didn't help things.

 

[Twisted Steel Performance]

The engineers I have talked with said the threads only need to be as deep as the diameter of the bolt, more threads didn't make a difference.

 

[SnowDrift]

According to that chart, Will, the factory 11-12 threads would be more than sufficient to hold the load.

 

[Twisted Steel Performance]

To be clear to anyone that may read this I will explain a few things concerning my customer builds with my halo girdle and splayed caps.

The halo girdle uses 12mm studs on all 10 inside bolt locations.
The splayed caps use 1/2" studs on the 6 cap outer locations.
That leaves a front and rear outer location that uses the stock 12mm bolt... that said I may change that once I talk to ARP and see if they offer a stud the length needed to fit under the girdle.

 

[SnowDrift]

Good information! Thank you

 

[MrMarty51]

A nut, torqued to spec on a bolt, holds by 1-1/2 threads in the middle of the nut.