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Home > Help Needed / General Tech Chat > Overlapping stud holes in K-build


280 Posts
Member #: 11231
Senior Member

Hi guys,

I'm currently plugging the block and I'm using brass for all the water and oil ways. All I have left now are those holes which will overlap the new stud holes. I've read several theories on what material should be used.

I tried to buy some cast iron round bar, but when I run a die through it, the thread produced didn't seem fine to me. It was all flake-y, so I thought it was not trustworthy.

I also bought some 10.9 and 8.8 grade galvanized steel bolts, but was thinking that they might be too strong compared to cast iron.

The last option I can think of, and I believe I haven't read it anywhere is to use 'bright mild steel' round bar and run a die through it. The material seems to be very machinable, so I guess tapping it wouldn't be a problem. However I don't know with regards to strength.

What are you guys using out there ?

Edited by Barrieri on 5th Sep, 2017.


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968 Posts
Member #: 1291
Post Whore

Suffolk / Birmingham

Well I'm in the iron camp. Maybe buy a sharper die? Haha


280 Posts
Member #: 11231
Senior Member

Yeah maybe that will work. I was thinking maybe defects in the material resulted in the flakey thread, but I guess it is a characteristic of cast iron


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2879 Posts
Member #: 83
Post Whore

Glasgow, Scotland

what about any material thatll fill the hole (brass/steel/whatever) and a wurth timecert to provide clean threads for the head bolts/studs.

I'v never done one of these conversions, but just throwing the idea out there.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Joe C

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12080 Posts
Member #: 565
Carlos Fandango

Burnham-on-Crouch, Essex

I like the timsert idea, especially if you were to use the original BMW bolts.

On 28th Aug, 2011 Kean said:
At the risk of being sigged...

Joe, do you have a photo of your tool?


280 Posts
Member #: 11231
Senior Member

But still, the materials in which the timesert is to be inserted needs to be strong enough to withstand the head torque.

If using brass to fill the original hole, then why just not tap it and use it already ?


56 Posts
Member #: 11458
Advanced Member

Melbourne Australia ... not a convict

" the miniman" down here in QLD uses cast iron threaded plugs, I'm unsure if he has any for sale atm. he's on here .... shoot him a pm and ask.

1977 Leyland mini Sunshine -- moleseted -- Named " Ray" becoming a 7 port efi slowly
1971 Nota Fang 145 bhp 5 port fun @ 450 kg
1969 Austin 1800 ute, 1800S running gear, tip rat and hardware store runner

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10782 Posts
Member #: 17

SouthPark, Colorado

For the ones at each end of the distributor side of the block, just wind in some low-grade steel bolts with permanent loctite. For the same (outer) ones on the other side of the block, use a taper plug, but don't drill into the water way in the same place as the original water hole; instead offset away to where the new stud hole needs to be, so the new thread doesn't contact the taper plug.

I added some pics of mine - note that I moved the middle three holes (distributor side of block). Not everyone does this, but I wanted to optimise, so bit the bullet and made it happen. The large 7/8" fine thread bolts on the "exhaust side" are there so there is a single large lump to (blind) drill & tap into, seems going small here is always at risk of creating issues by pulling out the plugs.

I had the benefit of doing these on my Bridgeport, and I used 2-flute slot mills for when drilling down between the differing materials to avoid any possibility of the drill wandering. If you are doing this in a drill press, you can still use a milling cutter - these won't want to wander as much, but you must have a very well clamped, rigid setup.

Edited by TurboDave16V on 5th Sep, 2017.

On 17th Nov, 2014 Tom Fenton said:
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Who remembers this first time around:


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46 Posts
Member #: 8956


I sacrifice an old cam for the cast bar, also use brass on water/ oil and not overlap stud holes, and the "old cam" on the ones that overlap.

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