3 bearing case with a Phoenix crank modification

[wild_willy]

I have removed the centre main bearing from the 3 bearing crankcase  to fit a Phoenix pressure fed 2 bearing crank. I now have no idea how to provide a block stud for the centre of the right hand side of the block where the centre main bolt used to be.

What have other people done to sort the missing stud which is part of the centre main hold down stud/bolt?

Also what do people do about providing additional lubrication to the plain cam centre bearing? Maybe a track cut into the bearing surface may help?

Thanks for any suggestions for the above.
Bruce

[Alan]

I’ve done a couple of these but not recently. I seem to remember a stepped stud in the centre main bolt hole and a drilling down from the valve chest for the cam bearing.

[Austin in the Shed]

Drilling down to let oil in the cam bushes.Stepped studs in centre holes,drill block to get 9 stud mounting.

[Stumpi]

Fit a 3/8 whit helicoil in the crankcase ,chop the centre main bolt to length required and thread 3/8 bsw. 
Ideally the top of studs flange should be level with crankcase or you may distort the block[shim if necessary]
Loctite stud into crankcase
i also have a stud in the valve chest[Dave Dye modified mine]
No mods to cam bearing oil supply . 
Its been like this for decades.

[wild_willy]

Thanks all for your valuable information.
The stepped stud using a right hand 3 bearing centre main stud would seem the sensible way to go. I have measured the existing hole which is 11.4 mm so it seem that a 9/16 W tapped  thread with the stud built up with weld might just work.

With regard to the cam centre bearing, the bearing is exposed to a splash feed via the stud hole and the oil passage to the bearing which has been opened up quite a bit with the removal of the upper main bearing housing. I am loath to drill any further holes in the sports block if I can avoid it. I might machine a small trough across the bearing surface to aid lubrication.
Any further thoughts on this approach?
Bruce

[Stumpi]

the hole in crankcase is correct size for a 3/8 helcoil tap and stud is 3/8 so only needs a die running down it.

[Chris KC]

the hole in crankcase is correct size for a 3/8 helcoil tap and stud is 3/8 so only needs a die running down it.

Alternatively you can run an 11.5mm drill down the holes and tap 1/2-20 UNF; then drill down the centre of a UNF HT bolt to make a thread insert to suit your stud.

[Stumpi]

Better with unc or whit, coarser thread is stronger, and a helicoil also spreads the load.

[Chris KC]

By all means - but those I've done in the past are over 2" long and set in permanently with Loctite - I can assure you they aren't going anywhere.

[Hairy]

Hopefully a couple of photos will appear with this posting?
I'm not sure if it helps, but the first photo shows a motor I bought that had been assembled using a silicone sealant. I thought that I had undone all the stud but couldn't separate the block from the crankcase.
I blamed the sealant and used mineral turps to soften it. Finally, I discovered the stud in the valve chamber.
This is a 3 bearing motor converted to two bearing.
The second photo shows the cleaned crankcase with extra studs for a new block and the centre bearing stud situation. I don't know if this helps at all?