17 replies to this topic

[Spider]

I was recently quized about the off-sets for off-set Boring the Big Bore Blocks for taking them out to 1380 and 1400 sized capacities.

 

I gave my friend the off-sets I've always used, which are those from David Vizard's How to Modify your Mini. He came back to me a short time later after consulting his own copy with some " ???? What ???? ".

After re-reading his notes a couple of times, I grabbed my own copy and check it, then compared to a photo of the same page in his book

I have a hard cover copy and upon checking that,,,, watch out !

 

 

The book in the back ground (my hard copy) is incorrect.

That in the foreground is correct !

I wonder how many followed this and got it wrong ?

I can't tell from either of these books when they were printed and if one is a particular later re-print than the other.


Check, then check again. Then to be sure, check again!  Measure 3 times, cut once !

[Cooper Mac]

I have the Third reprint from 1986 and it has the lower, correct diagram.

 

My Yellow Bible is the third edition from 1999 and has a different drawing, but the correct offsets.

[nicklouse]

Chris look on page 2 and it should give the date.

 

all mine have the correct info. HTMM 1984 and 1990  and the yellow “tuning BL’S “ 1989

 

and for those like me with old eyes look at the arrows.

[imack]

Took me a while to spot the arrows!!

[mab01uk]

I have a softback 1977 edition which has the incorrect diagram.

[Spider]

Chris look on page 2 and it should give the date.

 

OK, the only date I could see in both of these was Feb 1977. There's no other reference to say that one of these was a re-print or 2nd edition though.

[nicklouse]

 

Chris look on page 2 and it should give the date.

 

OK, the only date I could see in both of these was Feb 1977. There's no other reference to say that one of these was a re-print or 2nd edition though.

 

oh one must be special

[nicklouse]

 

[Spider]

OK, many thanks Nick, now I can see how they are marked up.

Neither of mine have a Reprint notation, so both first runs, but clearly, someone (probably David himself) picked up on this and had it fixed, however, clearly there was quite a number of issues that went out the door before it was caught !

[nicklouse]

OK, many thanks Nick, now I can see how they are marked up.

Neither of mine have a Reprint notation, so both first runs, but clearly, someone (probably David himself) picked up on this and had it fixed, however, clearly there was quite a number of issues that went out the door before it was caught !

Drop  him a message on faceache.

Edited by nicklouse, 05 January 2021 - 02:34 AM.

[Spider]

 

OK, many thanks Nick, now I can see how they are marked up.

Neither of mine have a Reprint notation, so both first runs, but clearly, someone (probably David himself) picked up on this and had it fixed, however, clearly there was quite a number of issues that went out the door before it was caught !

Drop  him a message on faceache.

 

 

Nick, I'm totally sure he's on top of it and highly likely he who spotted the error back in 77 !

I'll look him up all the same, been years since I had a nag with him,

[3VILC]

Probably dumb question so feel free to slap me its been a while since I researched any of this, but shouldnt both outside bores be offset by 0.15 and the inside 2 by 0.015? Or otherwise school me what is the purpose of offsetting the radiator end bore significantly more than the other 3?

[Spider]

Probably dumb question so feel free to slap me its been a while since I researched any of this, but shouldnt both outside bores be offset by 0.15 and the inside 2 by 0.015? Or otherwise school me what is the purpose of offsetting the radiator end bore significantly more than the other 3?

 

Sorry, I'm not quite understanding in which direction you are moving here ?

On the Big Bore Blocks,when you look across the deck the bores are fairly evenly spaced, though, 2 & 3 are closer together, so Bores 1 & 2 are moved towards the Water Pump and 3 & 4 towards the Flywheel to leave some 'meat' between cylinders 2 & 3 as this is already on the thin side. They are all moved towards the Camshaft to leave some meat between all bores and the Main Oil Gallery. This is what the lower of the 2 drawings in post #1 show.

On the Small Bore Blocks, the Cylinders are arranged such that there's quite a gap between 2 & 3, so looking along the Crankshaft line, Bores 1 & 2 are moved away from each other and likewise 3 & 4, though 4 is moved less to reduce the possibility of breaking in to the Oilway between the Pump and the Oil Pressure Relief Valve. All as shown in the drawing below;-

 

 

[GraemeC]

Spider - I get what 3VILC means:

 

In the big bore diagram, cyl 1 is shown as moving by 0.15" whereas cyls 2, 3 & 4 are shown to move .015" (0.015")

Is this another typo (that carries through) or should cyl one move 10x as far as the other two??

[Spider]

Spider - I get what 3VILC means:

 

In the big bore diagram, cyl 1 is shown as moving by 0.15" whereas cyls 2, 3 & 4 are shown to move .015" (0.015")

Is this another typo (that carries through) or should cyl one move 10x as far as the other two??

 

Ah, OK - now that I did miss ! Look at the detail and miss half of it !

Could be in for a rude surprise if one tried moving it nearly 4 mm (150 thousands) !