Underside

Finally the body was prepared for the paint job. We sanded and painted the underside of the chassis. First we used a light 1K rust preventive primer at the joining area of the panels. With some effort this paint can get between the overlapping panels and seal it from the rust. As a second step we sealed the panels, oversprayed it with 2k epoxy primer and finally coated it with stone chip protection.
Today afternoon the body was transported to the painter. They will start the work tomorow. All fingers crossed...

Some extra protection at this delicate area.

Engine assembly 4.

I assembled the cylinder head.

New valve springs, that work best with the camshaft.

One point that is prone to oil leaks on a mini engine is the timing cover area. I picked the best from my collection...

And sanded it a bit to get a flat surface.

Look what I found in my loft: a nos cast iron case water pump. It was the original fitment on period mini engines. Long out of production. It is my gift for Easter :-).

Finally a bit of painting here and there.

Engine assembly 3.

Engine.

The Cooper "S" engine was a miracle of its day. The power to weight ratio of the car was more than reasonable. Although 50 years have passed since that time, the engine is still up for its job, although can be improved at some points. The car will be a daily runner, so the most important factor is reliability. Most of the non-original items work in that direction, but we also would like to see a tad more power (as always :-) ), from the engine, if possible.

New cam bearings, hand honed to finish.

Cleaning the crank journals is very important task. Not to be overlooked.

This is the original nitrited EN40B "S" crankshaft. It is in perfect, std/std condition. It was a dilemma whether to use it or replace it with a "mundane" item. But finally the decision was made: it was meant to be used so it will be used :-). 

Some bushings in the gearbox were replaced now.

To be on the safe side, some bearings also.

Checking the end flow here is vital.

Just like using cam lube on the new camshaft.

Isky followers are the best for the task.

Timing in the cam may take a couple of hours. I used offset cam keys to set the timing.

Bodywork

Final touches on the body

There was a rear collusion at some point. Neither the boot lid, nor the laps line up. Need to be treated a bit.

Better, but still not perfect.

New front end fits generally good, but...

...still need some some adjustment here...

...and there.

Panel gaps are 4-4.5mms. As even as it gets.

But some parts still need some finishing.

Engine assembly 2.

The plan and the main non-standard components

There are hardly any "standard" Cooper S engines in the world. And that's not mainly because they were not built well by the factory, but rather due to the fact, that thees cars offer  LOT more fun if given that very little bit of "extra".

Soo ill we modify our engine? Definitely. When doing soo, one must be careful though. It is far too easy to make a dyno-day-only car, that will be awful to drive. Our goal was to "finish" the factory treatment and develop the car in a manner the factory should have done if only they had the components, and the extra money to be able to do it.

The non standard components are mainly on the picture. The cylinder head was slightly modified at a point, but was done not quite well. Now I reshaped the ports, and generally finished the factory design. I did not opened up the ports too much, rather I only reshaped them to get a more unrestricted airflow, but not to slow down the gasses. Std valve sizes were kept, but the seat were given a 3 angle grind to better the flow at partial lift situations.

To achieve some extra at mid and top range, a bit longer duration camshaft was used with a modern, more aggressive valve timing profile. To work with this camshaft, a special valve spring set will be used.

On the intake side, a Kn filter will be used to better the intake,and a freeflow, 3-2-1 long central branch manifold, with a medium bore RC40 exhaust system made of stainless steel will be on the exit side. This system gives a modest note, but quite nice on power, especially on mid range torque. Although the manifold looks quite nice, it will be covered in heat insulation to keep the heat at bay.

All thees nicely set up, will develop a healthy 85-90bhps. 

We also have some parts to better longevity and general reliability. We will use a superb cometic head gasket, and spec higrade cylinder head bolts and nuts to prevent gasket failure, which is quite not unheard of with big bore mini engines. Arp studs we use at the main and conrod bearings, new oil cooler and pipe will be there to protect the new engine from old debris left in the 40+ years old cooler.

Engine assembly 1.

Assembling an engine is always a delicate and delight full task. First in the row is a THROUGH cleaning, which takes quite some time. The engine should realy be as clean as possible before I check the tolerances and start the building session.

After cleaning the parts and the block, I have measured everything around the unit and checked if all tolerances fall between the factory specifications.

Engine Build Sheet

Camelot Restorations

Project:  Cooper „S” Mk3 WP	Displacement: 1293ccm
Engine type: A series, cooper S	Compression ratio: 1:9.75

Piston-bore clearance	1.	2.	3.	4.	5.	6.	Fact
	0.04-	0.04-	0.04	0.04+			0.035-0.063

Piston ring side clearance	1.	2.	3.	4.	5.	6.	Fact
1.	0.05*	0.05*	0.05	0.05+			0.04-0.06
2.	0.05*	0.05-	0.05	0.05			0.04-0.06
3.	0.05	0.05*	0.05	0.05			0.04-0.06
4.

Main bearing clearance	1.	2.	3.	4.	5.	Fact
	0.06	0.06+	0.06+			0.035-0.075

Big end clearance	1.	2.	3.	4.	5.	6.	Fact
	0.05	0.06	0.05+	0.06			0.035-0.075

Valve clearance	1.	2.	3.	4.	5.	6.	7.	8.	9.	10.	11.	12.	Fact
	0.06	0.05	0.05	0.05-	0.06+	0.05+	0.05+	0.06					0.05-0.075

Crankshaft axial free play:  0.14

After checking the tolerances, I balanced the con rods and the pistons. Con rods are end-to-end within 2 grams to one another. Total weight is 739g in average. Pistons are also 2 grans from each other, weighting 357g without the rings, and 377g with the ring pack average.

Gearbox 5.

After a bit of lamenting, we went for 3.44:1 final drive as a balance of cruising and acceleration.

The differential pin is an item that is also prone to wear. For longevity we went for competitions grade replacement.

Diff side covers get distorted quite common.

Some hand filing was necessary to restore the mating surface.

Diff bering preload is set by shims on the mini gearbox.