main cap fit to block

[Warp Speed]

the downward force of the rotating assy causes the caps to have the ends pull inward because of the bending force on the caps. this happens because of the clearance around the bolt holes and the pins are a tight fit into the caps to prevent any cap movement.

this is the reason that high dollar con rods use hollow dowel pins around the bolts to keep the cap and rod in alignment not just the clamping force of the bolts.

The dowels don't so anything really except align the cap. It is all about the clamp load!

[gmrocket]

I haven't seen anything mentioned yet that would be worth trying.

I worked in a diesel shop before and it was common to "reset" cap crush..only thing that work permanently was to use steel shim stock between each register and cap..little bit of loctite on a each scuffed surface and it would stay put.

I've done that on gas also and it works

Last one was a turbo Buick where the center caps just fell out on their own.

[rebelrouser]

On stock engines I have seen and used the methods mentioned to tighten main caps to the register with good results. On a racing engine when it comes apart with loose main caps, I tell my customers its junk. My experience is the reason the caps are loose is the old block just is not happy anymore and can't take the pressure. It causes problems down the road if you try and reuse them.

[gmrocket]

the downward force of the rotating assy causes the caps to have the ends pull inward because of the bending force on the caps. this happens because of the clearance around the bolt holes and the pins are a tight fit into the caps to prevent any cap movement.

this is the reason that high dollar con rods use hollow dowel pins around the bolts to keep the cap and rod in alignment not just the clamping force of the bolts.

Like the high dollar eagle rods on summit for $150?

[swampbuggy]

Since we got on a con-rod rabbit trail, IMO the jagged parting line between the cap and the rod itself used on the high dollar (3500 to 4000 USD) Pankl rods is paramount in keeping the BE round and the cap located at extreme forces seen at 9000 + RPM's . Mark H.

[ProPower engines]

The same thin dowel can be used to align main caps as well. Lots of diesel engines use a hollow dowel to locate the caps.
I have done that on some old resto projects where cap replacement was not practical. Also on some newer GM and ford blocks that were just basic street builds but no budget for caps and related machining operations but the thin dowels are easy to install and you can also knurl the sides of the cap as well to further tighten then in place. it is easier to make up some as the dowels used in some engines can be pricey to get from the dealer. Some 4130 bar stock drilled and OD machined then parted off to the desired length is all you need as some are about $15-$20 per dowel from the dealer.

[modok]

Hollow dowel around the bolt seems to be the ticket for straight engines, but on a v8?
Not sure, probably not?

[pamotorman]

Hollow dowel around the bolt seems to be the ticket for straight engines, but on a v8?
Not sure, probably not?

they do it on V-8 also. http://www.superchevy.com/how-to/engine ... an-rhs-ls/

[modok]

Yeah, and like I said, I'm not sure.