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PostPosted: Sat Aug 13, 2016 10:20 pm 
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attention to detail - it doesn't take that much effort to do it properly

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PostPosted: Tue Aug 16, 2016 5:37 pm 
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zulu_warrior1976 wrote:
Love those graphics of the 3 minis in your footer! How did you do that?


? anyone help?

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PostPosted: Tue Aug 16, 2016 5:49 pm 
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zulu_warrior1976 wrote:
zulu_warrior1976 wrote:
Love those graphics of the 3 minis in your footer! How did you do that?


? anyone help?

I'm only guessing but I think its just an image saved in your signature.

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PostPosted: Tue Aug 16, 2016 6:04 pm 
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It's called mini selecta. Modify the mini, click save, crop off the extra, upload the image and paste BBCode to your signature (don't think it works on all mobile devices though)
http://www.localminichat.co.uk/oildrippers-miniselecta/

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PostPosted: Tue Aug 16, 2016 6:56 pm 
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Irrelevant to thread.

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Last edited by RetroStyle on Tue Aug 16, 2016 9:50 pm, edited 1 time in total.

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PostPosted: Tue Aug 16, 2016 6:59 pm 
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Thanks or that link Timmy, very cool.

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PostPosted: Tue Aug 16, 2016 7:00 pm 
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timmy201 wrote:
It's called mini selecta. Modify the mini, click save, crop off the extra, upload the image and paste BBCode to your signature (don't think it works on all mobile devices though)
http://www.localminichat.co.uk/oildrippers-miniselecta/


One day I'll learn how to do this.

Brad

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PostPosted: Tue Aug 16, 2016 8:24 pm 
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looking good!

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PostPosted: Tue Aug 16, 2016 9:42 pm 
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OK, before this thread went all PAN AM Flight 73, this is where we were up to...

Mokesta wrote:
Ok, a bit more playing with my Twinky today ;)

This is the block I will be using:

Image

Bores measure 70.55mm diameter and need to go up a size.

I threw some of the bits on the block. Can't put the cam sprocket end plate on because I haven't cut off the stud for the chain guide in the head.
UK forums say these special hoses aren't that special and need to be modified to work. I think they are right as it looks like one will rest against the exhaust if not modified.

Image

Then I compared the BMW head gasket to the block and a BK450 gasket.

Image

Outer cylinder alignment (yes I have greased my bores, I like them greased):
Image


Inner cylinder alignment:

Image

Things I noticed:

The BMW block is an open deck and the BMW head has symmetrical water passages for each cylinder. It is the holes in the head gasket that control the flow of the water from block to head. There is a pattern to the holes in the gasket that ensures that the water doesn't just short circuit around in the front of the engine. Excluding the three holes near where the cylinders meet, there is only one hole around No. 1 cylinder and 4 holes around all other cylinders. The single hole in #1 is 5mm diameter. The other holes are either 6mm or 10mm. The 10mm holes are on the exhaust side of the head and opposite from the outlet.

This is a strong difference to a mini where the water passages are no different for cylinder 1 than cylinder 4. The mini does have bigger passages on the back side opposite the pump inlet and the thermostat outlet to encourage the water around the back of the engine.

So, with BMW having obviously thought about this cooling flow issue it was surprising to see that the drilling guide from SC recommending that all water jacket holes drilled in the block be 5mm. I think some more investigation is needed on this one.

Onto the holes in the block. The SC book commits precisely 1 short paragraph in its 60 pages to this fundamental step. :? It helpfully suggests to "drill and tap the hole out to allow a steel insert to be thread locked in place". Not much to go on me thinks.

I see 4 different diameter holes, three if you exclude the existing stud holes that are already tapped. They are:
Use -- Approx diameter
Studs -- 9.9mm
Water -- 6.3mm <--- the build guide says that the 8 of these at the engine number side of the block can be left un-plugged but all the photos show them plugged.
Push rod -- 10.2mm
water -- 12.5mm

I guess they could have said what diameter drill, how deep to drill (the deck appears to be about 13mm thick to the water jacket) and what size tap to use but that would be too easy.

I read on the UK forums that people recommend using threaded cast iron rod so that the drill holes that overlap the existing holes don't get drill wander due to the different strength materials. I see from old pics on here that most of the holes are filled with set screws. I would like to know if it is worth the effort to get rod and get it threaded to the 4 different sizes required or are simple low strength grade screws satisfactory?

I know Matt Read will know these answers but I'd like to find out and put them in here for completeness. There is fly cutting pistons and sealing up the head to do for this conversion but I think people would agree that the block modifications are the most intimidating part of this build. They are too poorly described in the SC book for the money.

While I'm on this little rant here are the other elements not properly described in the SC book:
1) Oil passage in the head. Where to drill and where to block if you don't want the external line
2) Oil feed to the head. The 'jackshaft' that you can buy from SC is modified to allow increased oil flow to the head. Ok, but if I want to use the camshaft I have, will I get enough oil to all those cam shaft bearings? What can I do to my cam to make sure I do?
3) The alloy timing plate that goes on the front of the engine has a big hole for the mini's cam. There is another alloy piece that goes in this hole and has the shaft seal in it and an o-ring around the outside. I assume that the steel mini camshaft restraining plate (three holes for screws and one to let oil out) is used between these two. It could be left out but then there doesn't appear to be anything stopping the cam walking out of the block. :roll:
4) The crank pulley is moved out towards the radiator by this conversion. SC will know how much by and could say so we know how much we have to move the water pump pulley and the alternator by to match but no, we have to work it out ourselves.

I'm sure there are other things that will crop up but these are the ones that stand out in the first 5 minutes.

Of course none of this is rocket surgery and I will get through and over it but If this is your business to publish a how-to guide, then you want to do a better job than SC have done.

M


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PostPosted: Tue Aug 16, 2016 10:10 pm 
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timmy201 wrote:
It's called mini selecta. Modify the mini, click save, crop off the extra, upload the image and paste BBCode to your signature (don't think it works on all mobile devices though)
http://www.localminichat.co.uk/oildrippers-miniselecta/


Thanks.
Irrelevant to thread or not, that's awesome!
Cheers.

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PostPosted: Tue Aug 16, 2016 10:15 pm 
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I have been doing a bit of homework on the hole plugging.

There are 4 different diameter holes to plug. The existing head studs are already tapped to 3/8x16tpi.
The other 3 holes are:
Use -- Approx diameter
Water -- 6.2mm to 6.4mm (1/4 inch nominal)
Push rod -- 10.2mm to 10.5mm
water -- 12.6mm to 12.75mm (1/2 inch nominal)

I notice that the head studs are the only UNC threads in the block. All the others that I found were UNF. So I looked at UNC, UNF and Metric thread sizes.

Options are:
6.3mm water holes --> Drill 6.6mm and tap 5/16x18, Drill 6.9mm and tap 5/16x24 or Drill 7mm and tap M8x1.0
10.2mm push rod holes --> Drill 10.8mm and tap 1/2x13, Drill 11.5mm and tap 1/2x20 or Drill 10.8mm and tap M12x1.25
12.7mm water holes --> Drill 13.5mm and tap 5/8x11, Drill 12.9mm and tap 9/16x18 or Drill 12.75 an tap M14x1.25

That's all well and good but you need to get a drill, a tap set and something to thread into the hole so if they aren't common sizes you're stuffed. The 9/16UNF size appears rare and the fine metric threads are also a bit scarce in the larger size. Looks like UNC is the way to go.

What about the issue of the inserts being too hard and the drill wandering when drilling for the new holes? I looked at the pattern and there are only two types of holes that overlap the insert and the new hole. These are the outer two new studs on the engine number side overlapping with the old stud positions and the new water drillings on the same side overlapping with the 1/4 inch plugged holes. That means, apart from the head skimming operation, the strength of the inserts for the push rods and the 1/2 inch water holes can be whatever.

I looked around for screws, bolts or threaded rod that would be about the same strength as typical cast iron engine block material. This is actually hard to do because the yield strength of most commercial bolts is about double that of the cast iron. Really low grade "standard hardware grade" bolts appear to be metric coarse or BSW.

I see that someone on here many years ago (user jspink, anyone got contact details for him?) got threaded rod turned out of grey cast iron. The cast iron is available as a 25mm bar stock so that is an option I am getting pricing on.

Anyone care to recommend UNF, UNC or Metric and a reason? Is there any difference in the ease of tapping between UNC and UNF? Do I want more or less cavity for sealant / locking compound? The UNC appears to allow a looser fit. How common are the sizes in the list above?

The UNC and UNF taps appear to be relatively easy to get. Most of us probably have the smaller sizes already for cleaning out threads.

I probably shouldn't worry about any of this and just hand the block to Matt but there is some fun in the researching.

M


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PostPosted: Wed Aug 17, 2016 8:23 am 
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The holes that need plugging, couldn't you just bronze them up rather than worrying about drilling/tapping them? Or am I missing something?

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1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
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PostPosted: Wed Aug 17, 2016 10:58 pm 
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Any reason for matching plugs to the block in terms of yield? I thought thermal expansion would be more relevant. Other considerations, the smaller the plug the less area exposed to pressure, and the head studs aren't cast iron.


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PostPosted: Thu Aug 18, 2016 3:00 pm 
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My 2c re drill wander. Yes it is a serious problem.

I have had experience drilling into 2 or more dissimilar metals, when I used to modify Mini rocker posts for an offset shaft +Corolla rockers. In this case it was drilling steel + iron + nickel bronze in the lathe. So I used a slot drill, then bored to finish size.
My solution for your block mod- don't use a twist drill. Set it up on a mill, and use a slot drill instead. Yes you can plunge cut with these.

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PostPosted: Thu Aug 18, 2016 8:22 pm 
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Location: Wodonga - Vic/NSW border
drmini in aust wrote:
My 2c re drill wander. Yes it is a serious problem.

I have had experience drilling into 2 or more dissimilar metals, when I used to modify Mini rocker posts for an offset shaft +Corolla rockers. In this case it was drilling steel + iron + nickel bronze in the lathe. So I used a slot drill, then bored to finish size.
My solution for your block mod- don't use a twist drill. Set it up on a mill, and use a slot drill instead. Yes you can plunge cut with these.


I was gonna ask if that was the best option... is it OK to use the slot drill to basically do a ~6mm pilot hole, then use a twist drill in to that, or will it still go off-centre?

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