Dowelling The Main Stud Girdle To The Block

[GTRNUR]

Has anyone ever tried doweling the main stud girdle to the block to eliminate girdle walk, while not also having to deal with added below the block height that girdle plate/adapter plates make?

I figure it could be done with a bunch of 8mm tool steel dowels next to the main bolts, or alternatively with hollow chromoly dowels that would slip over the main studs and be recessed into the block and girdle.

Doing this as opposed to heading down the billet main cap/girdle plate path would mean no align bore needed, so typical wet sump pumps are still able to be used.

I would argue that it would be just as strong from a main-cap perspective too, as eliminating girdle walk ties the girdle and the block together more firmly.

Where as an alloy billet main cap can still walk on the block, and is relying entirely on the rigid strength of the plate to reduce block flex to reduce main cap walk.

Any thoughts?

[zebra]

I can't speak for the RB

but i've know guys who have had very limited success on Holden V8s and Clevelands.

The caps still walked, but not as much. The issue was fixed by going to steel 4 bolt mains caps.

But given the RB has a girdle it should work better.

[Ben C34]

Dowels aren't really for holding things in place, just aligning.

I would try to machine edges on the girdle and block, and fit correctly sized keys either side of the girdle between the block.

[GTRNUR]

Dowels aren't really for holding things in place, just aligning.

I would try to machine edges on the girdle and block, and fit correctly sized keys either side of the girdle between the block.

For a cylinder head, yes I'd agree.

But what I have in mind is more like you'd see on a connecting rod, with a dowel that is hollow, tapered and is an interference fit into the block and girdle cap.

[Shoota_77]

This is only speculation but if someone could x-ray a block they may be able to get an idea of whether going a 4 bolt main cap was possible like old Holden V8's and many others? There's the added benefit of locking everything together by stopping the bottom of the block expanding.

It may throw the whole thing out of whack though by introducing new stresses onto the block.

[jiffo]

From memory the girdle has machined edges mating to the similarly machined block at each main.

Would think this location is pretty good in sideways load.

Are you concerned about fore/aft movement of the girdle?

[GTRPSI]

The caps are all tied together by the girdle so cap walking is not that much of a issue on RB engines.

Lets also not forget that to set the thrust bearing face, we need to be able to walk the center cap, when they are tied, they all will walk to set it.

If the caps were individual id say pinning would be needed.

Hollow centering caps like on the rods are not designed for side loads, they are for accurate positioning of the cap for tightening, neither would hollow pins be any good as they are weak for side loads, for accurate firm centering you would need tapered solid pins.

To do it is not hard, you can buy the tapered pins in long lengths and cut them to the tapered section width you need, the reamers are available from engineer supplies as are the pins (not cheap i might add)

The issue is there is not much room/meat in the block or girdle to place a pin without weakening both.

I looked into it as ive done the solid tapered pin mod to 265 Hemi engines mains in the past.

I even pinned in the big end bearings into the rods on 265's in the same way in the past to combat bearings spinning from rod bolt stretch.

[r33_racer]

I've dowelled the billet main caps to the block many times now with custom made en26 dowels. Been doing it for big hp drag engines for the last 3+ years. It works very well and it makes the machining and assembly process far easier and quicker.

I doubt if you could get away with dowelling the factory girdle and block and not require a tunnel hone at the minimum.

I machined up hollow dowels to locate around the main studs in case you wanted to know. I've had no dramas with this method to date.