Need to move a stud on the head should I weld it proffessionally
or use mild steel tap with a perma sealant loctite then re tap
for the stud position I need? Will the cast iron be a problem
with the mild steel tap?

If you know there is enough solid cast iron to tap into, there will be no problem.
Cast iron drills taps easily with a high speed steel drill/tap/lathe cutter.How do you think they tap the thread in a g-clamp frame? It shouldn't be a problem.

In this picture the red areas highlight the main problems stud areas
while some of the inner ones need a few mm the blue ones are spot on.

Please click on the image below for larger view

Attach file:

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  ca vs zx tap.JPG (199.92 KB)

There is a high nickel content tig or arc made for this type of job
where depth is achieved without porous or density issues.
Ill have to take the block to a good welder but cast iron specialists
are hard to find these days.

Anyone in melbourne that knows a cast iron welder?

Thinking about this on the train ride home. I think you just might get away with screwing in studs that end up flush then drilling and retapping. I'd think if you used a high temp metal filled epoxy on the thread that would probably hold it. They're out in the water jacket so they should get too hot. Welding there's going to be tough.

If you wanted to be really tricky a thread with a really light taper might just achieve an interference fit and if the surfaces are really clean and you get it tight enough the surfaces can fuse together.

In anycase it's not going to be easy.

Fill the holes with Nickel? Ideally poor it in molten (the nickel helps stop phase transformation at the interface, martensite = cracks).

Yet another idea, fill the holes with metal filled high temp epoxy, drill and tap for a helicoil to match the head bolt or a suitably sized bushing to spread the stress around?

Just my thoughts, maybe they'll inspire the solution

Found something relevant whilst fafting about...

http://datsun1200.com/modules/newbb/v ... ASC&type=&mode=0&start=40

Thanks, I wont be giving up.. Too much invested already!

I haven`t got any pics of the finished chain drive on the computer but here is one with the plates bolted to the front of the block and a separate bit on the head. It uses one Morse silent chain and standard bike tensioners that bolt to the plate you can see in the pic. The swinging guide is controlled by a standard CBR tensioner (which is a non oil, spring loaded ratchet type).Open in new window


EDIT: You`re a bit lucky with the the GA head with nearly all the holes lining up! Will there be plenty of thread boss for the other two?
When using the CBR head, all the head studs have to be moved out 3mm. I had threaded cast iron inserts made to fill the original holes the had new holes drilled and taped in the deck to suit 1/2" ARP studs. I can use the standard MLS bike head gasket.

Ive made some vernier cam sprockets for the cams that look a bit cool. but i still need to make the timing case cover.
The pistons and rods are made and the crank has been lightend, offset ground and balanced.
Its nearly ready for assembly, but have too many other things on to finish it at the mo.

Thank you for the tips!

Simon made cast iron threaded inserts taps which Id like to do but have no idea.

Quote:---------
I had threaded cast iron inserts made to fill the original holes the had new holes drilled and taped in the deck to suit 1/2" ARP studs. I can use the standard MLS bike head gasket.
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I had some idea on using some kind of loctite or epoxy for the inserts and the more
I think about it if I can get the cast iron inserts then I could lock and stick
them in using the method for cracked industrial blocks. Then the L&S get machined smooth.
This will allow me to use Kawa head gaskets.

The welding I was thinking of was this method
http://www.youtube.com/watch?v=ejGttywG98w&feature=related

The lock and stitch is interesting
http://www.youtube.com/watch?v=Pq0wfU4ZaKk&feature=related