Joined: Sep 2017 Posts: 79 Threads: 12
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Location: Melbourne
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
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Location: Cheshire
Car type: Race Ulster, 1926 Special, 1927 Chummy, 1930 Box
22-08-2024, 09:00 AM
(This post was last modified: 22-08-2024, 09:01 AM by 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.
Alan Fairless
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22-08-2024, 11:08 PM
(This post was last modified: 22-08-2024, 11:09 PM by Austin in the Shed.
Edit Reason: Correct error
)
Drilling down to let oil in the cam bushes.Stepped studs in centre holes,drill block to get 9 stud mounting.
Joined: Aug 2017 Posts: 99 Threads: 2
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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.
Joined: Sep 2017 Posts: 79 Threads: 12
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Location: Melbourne
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
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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.
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Better with unc or whit, coarser thread is stronger, and a helicoil also spreads the load.
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Location: Darkest Bedfordshire
24-08-2024, 10:47 PM
(This post was last modified: 24-08-2024, 10:47 PM by 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.