Joined: Aug 2017 Posts: 952 Threads: 38
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Stripped down a block today, unscrewing the studs a number of them wobbles as they unscrewed initally I thought they had beem bent.However on cleaning the threads with a tap it was apparent some holes had not beeen retapped squarely, to compensate te studs had been bent to an upright position
Cleaning the block face revealed other bodges, 3 of the retapped holes are about half a hole out.
Is there an engineering drawing available that gives the correct position of the studholes so that this can be set up on the mill and the holes redone at the correct centres.
I know I could just measure the holes in a cylinder head, but a proper drawing would be better.
I could just get another block, but most seem to have issues of one sort or another.
Any help greatly appreciated.
Joined: Mar 2018 Posts: 694 Threads: 33
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Location: Lot region FRANCE
If the block is that bad, you would have to go to 3/8" helicoils/ then make special studs which were 3/8" in the block and 5/16" for the head. Is there enough metal in the block to do this as the O/d is about 0.468" for a BSF threaded helicoil. Because the diameter is increased, you could go BSF instead of traditional BSW in cast iron. Slightly smaller than 3/8 inserts would be to choose 8 or 8.5 mm ones.
It sounds like even the good holes would benefit from being helicoiled back to 5/16" BSW if you are going to this sort of trouble.
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07-04-2018, 10:12 AM
(This post was last modified: 07-04-2018, 10:19 AM by Austin in the Shed.
Edit Reason: add content
)
If the holes are a 1/3rd out of position Gene you're going to struggle.They have probably been drilled by hand,the drill drifting from the tough stud to the softer cast iron.
Going one size larger will only take up 1/32" offset at best and then it will break out the side of your plug and probably move.
The holes between the cylinders are the most important as they can crack into the bores.
On one crankcase ,Sump thread,I had to tap it out to 7/16" Unf (most convenient) Plug it and to tap out 1/4" BSW.
Joined: Aug 2017 Posts: 1,337 Threads: 34
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Location: Cheshire
Car type: Race Ulster, 1926 Special, 1927 Chummy, 1930 Box
07-04-2018, 10:25 AM
(This post was last modified: 07-04-2018, 10:26 AM by Alan.)
What you could do, and I know it’s not ideal, is get the studs as close to position as possible using inserts as you suggest and take up the remainder by enlarging the stud holes in the head.
Alan Fairless
Joined: Dec 2017 Posts: 1,160 Threads: 68
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Location: Nottinghamshire. Robin Hood County
Car type: Austin Ruby Mk1 1935
Hi all, I too found a number of bent head studs in my block when I stripped it down. I have no pillar drill etc to put things right so had to do a bodge. I replaced the straight studs and made su.re the head slid on and down them to sit nicely on the block. No gasket at this stage. I removed the head and replaced the first of the effected stud holes with a straight stud. Using the head as a guide I used a rubber hammer to bend the stud to a nice fit. Again checking with the head that it slipped down fully and easily onto the block. I repeated this until all the studs were replaced. I checked the points where the bent studs met the block to see the bent area caused any problems and rubbed each one with some coarse emery cloth. Cleaned it all up and re assembled with no problems.
John Mason
Would you believe it "Her who must be obeyed" refers to my Ruby as the toy.
Joined: Mar 2015 Posts: 5,445 Threads: 231
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Location: Scotchland
I woul find another block to use - the clues for impending disaster are all present.
Joined: Mar 2015 Posts: 5,445 Threads: 231
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Location: Scotchland
I would be looking for another block - if you don’t see the need, then you should use it.
