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Rudi's 1430 supercharged classic mini #1198239
07/04/2011 21:08
07/04/2011 21:08
Joined: Dec 2005
Posts: 1,670
SW London
Rudidudi Offline OP
My life on the forum
Rudidudi  Offline OP
My life on the forum

Joined: Dec 2005
Posts: 1,670
SW London
Well I bought her (a her because 'Hell hath no fury like a woman scorned") and when i finish with her she will be 'Savage' (and im hoping nothing like Lilly wink ).

I saw her advertised in the freeads in Chatham, i had always wanted a tax exempt mini and here was my opportunity!

She had been garaged for 6 years and had undergone a full restoration a few years before that. Some of the 'resto' has a bit to be desired. The paint was applied quite thick and there are dreaded oversills !

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On the whole she looks a solid car, all standard apart from bucket seats and a full roll cage !

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After some negotiating we agreed on a tidy sum of 225 quid driving

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I have quite a few plans for her that involve a changes to the engine, fiesta brake conversion is planned and some suspension mods. On the whole, and at the moment, i want her to look fairly standard (in so far as is possible).

The current plan is to build the following spec engine:-

A+ 1430cc
E45 Supercharger blowthorugh
Twin SU carbs
Ph3 cam
Ported head
Megajolt
Ultralight flywheel, preverto with paddle clutch
SC drops
x-pin diff
2.9 fd

Things may change but this is the current plan. I intend to build an engine that has a torquey delivery over raw bhp.

The first stage (choosing a suitable block for the build ) is documented below.......

Re: Rudi's 1430 supercharged classic mini [Re: Rudidudi] #1198244
07/04/2011 21:13
07/04/2011 21:13
Joined: Dec 2005
Posts: 1,670
SW London
Rudidudi Offline OP
My life on the forum
Rudidudi  Offline OP
My life on the forum

Joined: Dec 2005
Posts: 1,670
SW London
Block selection - Part 1
Assessing cylinder to oilway thickness

If a block is intended to be bored out to accept oversize pistons it is important that the block can be bored out without cutting into the oilways, or leaving the wall of the oilway so thin that it may crack or collapse.

The first stage of the engine build is to select the best block for the application. As i will be boring the block to accept 73.5mm pistons the block must be assessed for suitability.

You can see below a block on a small engine stand. A suitable adapter is used in order to hold the A-series block on the engine stand. I cannot stress how much easier it is to work properly on an engine when it is held securely on a stand. The engine stand is in my opinion an essential piece of garage equipment.

click to enlarge

The first check carried out is to assess whether the block will support offset boring by the required amount.

The clearance between the oilway and cylinder number 4 must be checked. A dowel or drill is placed into the oil way. In this instance the 8mm drill bit was the largest size that fitted with no play.

The first check is to verify whether the oil way is parallel to the side of the block. The distance between the edge of the block and the drill bit is measured near the block and at intervals. In this instance the spacing was constant which signifies that the oilway was parallel to the block.

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A measurement must be taken between the side of the block and the inside of the cylinder. The side of the block is cleaned on any rust so that an accurate measurement can be recorded.

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A measurement is taken, in this case with a vernier. The vernier is zeroed and the outermost point of the cylinder is measured against the side of the block. Care must be taken to ensure that the measurement is taken parallel to the block and cylinder. The smallest measurement signifies the thinnest part of the block as illustrated.

In this example the distance between the cylinder and the side of the block was 0.929"

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The next stage is to measure the distance between the side of the block and the drill bit. A vernier or depth micrometer can be used for taking this measurement.

In this case a metal engineers rule is used as a straight edge against the side of the block. The metal rule is measured and the vernier is zeroed. This means that when the vernier reads '0' the tip is level with the side of the block.

The vernier is opened until the tip touches the drill bit. It is important that the base of the vernier is flat and parallel with the metal rule, and that the tip of the vernier touches the central part of the drill bit.

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The measurement taken above was 0.518". This represents the thickness between the side of the block and the outermost part of the oilway.

Now we need to do some maths to calculate whether this block will accept the required overbore.

Parameters
Block side to oilway = 0.518"
Block side to cylinder = 0.929"
Oilway diameter = 8mm = 0.315"

Calculations:

Distance between Oilway and Cylinder =
0.929" - 0.518" = 0.411"

(Distance between Oilway and Cylinder) - Oilway diameter =
0.411" - 0.315" = 0.096"

This is the nominal distance between the cylinder and the innermost oilway wall.

Now we need to take into account the boring and offset.

The cylinder will be bored out by 0.113". The increase in cylinder diameter is divided by two as we only need to take into account the increase on the one side of the cylinder.

In addition the boring is offset by 0.015". This means that cylinders 3 and 4 are effectively bored 0.015" outwards from the centre of the block.

So:
Cylinder to inner oilway wall - half of bore increase - offset = ?

0.096" - (0.113/2) - 0.015"

= 0.096" - 0.0565" - 0.015"

= 0.0245"

This signifies that if the cylinder is bored by 113 thou and offset by 15thou, the distance between the cylinder wall and the oilway will be 24.5 thou.

Five blocks were measured for suitability. Two blocks, if bored would have resulted in the cylinder exposing the oilway. Two blocks resulted in 10 and 11 thou cylinder to oilway clearance. So far this block is the best.

This method was carried out on a block with standard sized cylinders. It is based on the assumption that that the bores and oilway have been cut correctly at the factory and are parallel to the side of the block.

Block Selection - Part 2
Assessing cam follower tolerances

This check is not deemed an essential, but good practice (and a further consideration in terms of block selection) if sufficient donor blocks are available.

The cam follower and the amount of slack with which it fits in the follower hole can affect the performance of an engine. As the camshaft rotates, any slack between the follower and its hole will be taken as the vertical movement of the follower also takes place. Therefore the accuracy of the camshaft timing will be compromised if the follower does not fit snugly.

The check is carried out with a gudgeon pin from a 1275 engine. The nominal size of a gudgeon pin is 0.8125". Typical variation of a gudgeon pin is 0.0005" (half a thou) under the nominal size, therefore 0.812" to 0.8125" .

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The gudgeon pin has to slide in the hole with no 'wiggle'. A tight fit is essential for a good engine build. If the gudgeon pin slides in with sufficient slack so that it can be wiggled in the hole the engine build will not be optimal.

The above describes a method using the feel of the gudgeon pin to evaluate the tolerances. Should you wish to measure the differences between the hole and the the cam follower a maximum clearance of 0.002" should be aimed for.

click to enlarge

Re: Rudi's 1430 supercharged classic mini [Re: Rudidudi] #1198249
07/04/2011 21:17
07/04/2011 21:17
Joined: Dec 2005
Posts: 1,670
SW London
Rudidudi Offline OP
My life on the forum
Rudidudi  Offline OP
My life on the forum

Joined: Dec 2005
Posts: 1,670
SW London
Next on the list after the initial block prep was to measure up the con rods and make sure they were fit for purpose.

click to enlarge

The rods were bought a few years ago and are becoming quite rare. The 1430 conversion requires A521 or A625s, often referred to as cooper s rods. The big ends are 1.625", same size as 998 big ends! It is important that they are in good condition with the extra power of a supercharger and increased capacity smile

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Lovely stuff!

They were all numbered, possibly from the factory. Viewing the con rod from this position will reveal any damage that may have been caused by a careless engine builder when splitting the rod. Hammer marks and burrs are often found on the edges of the cap. If the cap needs any persuasion it should be done with a small copper or hide mallet, never with a normal hammer. As you can see from the photo these were in good condition.

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The next job is to give them a good clean and remove any oil and dirt, a bit of brake cleaner and a blow with the air gun...

Any deburring to the cap mating edges would need to take place now with a file. I have seen con rod caps butchered with hammers and even screwdrivers to prise them apart before. Luckily these were fine in that respect.

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A visual inspection follows, checking in particular for the markings on the journal thrust faces. All these con rods had the machining marks present and even. This is a very good sign in that it shows that the rods have run in the previous engine true, that is to say they have not been forced at an angle due to off square cylinders or poorly even machined crank journals. Another very positive sign.

Next we move on to preparing the rod for measurements. Firstly the inside of the big end is cleaned up with some 1000 grit emery paper and paraffin. No excessive force, just enough to remove the thin film of dirt, grime, film, etc.

click to enlarge

his is done so that there is a smooth finish ready for measuring...

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and the same is done with the small end

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and after...

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Next, measurements and essential tools of the trade. Below the micrometer, nominal measurements for the conrod big end and the dial bore gauge smile

click to enlarge

Measuring the hole, the dial bore gauge is zeroed on the micrometer and then measurements relative to the micrometer setting are taken. The two figures will enable us to determine the actual measurement.

click to enlarge

n this instance the sizes were +0.00025" the smaller nominal, so 1.7705" + 0.00025" = 1.77075", right in the middle of the range smile

The small ends were measured in the same way based on a nominal 0.8121" gudgeon pin size. All the small ends measured 0.001" - 0.0015". The minimum interference fit is 0.0007" so these will be a nice tight fit!

So a critical part of the planning and preparation stage is partially completed, I still have a couple more checks to do (to follow).

Re: Rudi's 1430 supercharged classic mini [Re: Rudidudi] #1212475
10/05/2011 00:45
10/05/2011 00:45
Joined: Dec 2005
Posts: 1,670
SW London
Rudidudi Offline OP
My life on the forum
Rudidudi  Offline OP
My life on the forum

Joined: Dec 2005
Posts: 1,670
SW London
The next stage of the build required the crank. This was stress relieved by grinding smooth the casting marks and any sharp edges. The work was carried out with an angle grinder with a soft pad and then a flap wheel with various grades of abrasive roll to polish the surface.

Once complete the crank was sent off to be machined. The 1430 build needs some specific machining, namely offset grinding of the big end bearings in order to increase the stroke. This machining is carried out on a pre A+ crank.

The work on the crank included:

- Big ends offset ground 84.3 mm
- Mains reground 0.010"
- Wedged
- X-drilled
- Balanced
- Hardened (ni-tempered)

click to enlarge click to enlarge click to enlarge

As with any good quality build, components should be measured and sizes verified. The measurements were as follows:-

Nominal pre A+ main bearing journal: 2.0005" - 2.001"
(Nominal A+ main bearing journal: 2.0011" - 2.0017")

Main journal measurements:
#1 journal: 1.9904"
#2 journal: 1.9904"
#3 journal: 1.9905"

A variance of 0.0001" (one tenth of a thousandth of an inch) all within acceptable tolerances

Big end journal measurements:
#1 journal: 1.6258"
#2 journal: 1.6253"
#3 journal: 1.6251"
#4 journal: 1.6253"

A variance of 0.0007" (seven tenths of a thousandth of an inch), again all within acceptable tolerance.

Watch this space for the next updates smile

Re: Rudi's 1430 supercharged classic mini [Re: Rudidudi] #1516975
28/11/2014 18:05
28/11/2014 18:05
Joined: Dec 2005
Posts: 1,670
SW London
Rudidudi Offline OP
My life on the forum
Rudidudi  Offline OP
My life on the forum

Joined: Dec 2005
Posts: 1,670
SW London
It has been a long time since the last update, life sometimes gets in the way of projects wink ...so a bit of an update:

I started working on the head. Starting with a course cut and shaping with a carbide bit:

click to enlarge

The shape of the ports is more important than the absolute size in order to make the flow efficient and also maintain gas speed.

The first stage is taking out the valve boss which imposes a massive restriction on flow, and of course shaping.

I will be fitting larger valves so the seats and throat on the inlets have been worked on, you'll see that the inlet seat is about 1mm. This will widen a tad when the seat is recut for the bigger valve.

The shapes of the work is good, so this was an exercise in looks over function. Many head builders also do a bit more and make it look shiney with a finer polish. There are various threads discussing how this can harm performance.


click to enlarge

click to enlarge

Then i got distracted and saw these so I had to snap them up! They will need to be fully rebuilt, a new kit from burlen awaits.

click to enlarge

... and back to the head work, now on to the stone to get rid of the crude cuts. This is more for aesthetics as research has shown that there arent any gains from this in perms of performance, just looks tidier.

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Next is the fitting of the valve guides. Before this the head needs to be cleaned and dried, both the spring seat and the guide hole need cleaning.

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Cleanliness on a rebuild is key. Any dirt that sits under shims etc. can alter rocker geometry and prejudice optimum setup.

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The guides are pressed in with a collar that ensures the guides are pressed in to the correct height (and uniformly).

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Inlet guides done...

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Next stage is to ream the guides, do some maths and work out chamber volume required for the head to match the CR for the specification I have chosen...


Re: Rudi's 1430 supercharged classic mini [Re: Rudidudi] #1516995
28/11/2014 20:33
28/11/2014 20:33
Joined: Dec 2005
Posts: 1,670
SW London
Rudidudi Offline OP
My life on the forum
Rudidudi  Offline OP
My life on the forum

Joined: Dec 2005
Posts: 1,670
SW London
Calculations...

click to enlarge


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