1981 Mini City 1000

[ctwomey]

Hi all,

Just thought I would kick off this thread on my new Mini. I bought the car in October of this year. It's an original Dublin car, matching numbers etc. so hoping to keep it as original as possible. Body work is in exceptional condition for a 39 year old car. Still will require some welding. First goal is to get the body shell 100% first before looking at the mechanics.

So far I have stripped it down to the bare shell. Only a few rubber grummets, rear brake line and fuel line to remove. Most recently removed that dreaded bitumen sound deadening off the floor and rear seat panel, messy stuff and filled a bucket with the stuff. Soft mallet and flat head screw driver worked well.

Some of the existing panels will need a bit of panel beating. Panels that will require replacing include, battery box, drivers door outer sill, possibly door and boot outer skins, front end is quite battered too as it got a knock before and was poorly repaired, nothing serious though.

Struggling to identify the red colour code so if anyone knows it would be greatly appreciated. I think it is BLVC287 Carnelean Red (CDE).

This isn't a short term project. Going to take my time.

[woody]

That body looks fairly solid alright. Good to see another one saved. Good luck with build.

[ctwomey]

Given that the weather has been rather cold, instead of doing some body work I decided to start rebuilding the engine.

Crank looks really good with no marks on the journals. I will get it verified in a machine shop. The seized pistons have come out of the block too and I have started to strip the block including water and oil plugs to remove all the grime.

Removed 95% grime using an engine degreaser. Who knew it was yellow

Head and Block are now soaking in a bath of argi-grade molasses to remove all internal rust from the water jackets.

I will remove both the Head and Block this weekend and power wash before putting back in the molasses for another week.

One thing of note I have discovered is that the 99H/791P engine is an A Block while the 99H/791PZ is the A+ Block. Other items are shared e.g. pistons (6cc - Low CRs) are the same. Not too sure that Guess Works picks up the subtle change as it just comes up as an A Block.

[DaveC]

Very good, keep us updated on progress!

[Billy]

Always enjoy reading a good restoration thread. Keep it up.

[Jknight]

It's amazing to see the differences with Irish registered cars and their UK counterparts for rust. Looking forward to seeing the project, I'm currently starting my own one.

[ctwomey]

After almost 3 weeks in the molasses bath, the engine block and cylinder head have come up rust free. A quick clean with the power hose and a spray of WD40 to prevent flash rusting I have now brought them down to High Precision in Tullow.

Minimum skim of the block deck to verify flatness. New cam bearings and also remove the broken engine id tag rivet the broke will removing.

Minimum skim of the cylinder head plus the valve seats will be recut as they are a bit pitted on the 2nd and 3rd cylinder exhaust valves. Broken heater valve stud will need removing too.

Still need verification on the big end and main journals before ordering bearings. I have only one micrometer and it doesn't cover that range. Need a few more fine measuring tools. The good ones are kinda pricey.

Original pistons are shot plus they are the low CR ones too. So have decided to rebore out +20 thou and using new Powermax 20950 pistons that are flat-topped and bullet proof and by my own calculations should bring the CR from 8.3:1 to 9.6:1.

[woody]

You might want to consider hardened valve seats to make the head unleaded. I presume you are uprating the cam

[ctwomey]

You might want to consider hardened valve seats to make the head unleaded. I presume you are uprating the cam

Correct, planning on using a SW5-07 cam as it seems to be a great all rounder. Going to spend the minimum on the head for now as it is an early CAM4810 and not the later one with exhaust valve seat inserts. Really just a quick cleanup. I have my eye on a 12G202 which is on an engine in my father in law's house that would be a more suitable head to have all the work done on. It would be the same head as an early 997cc Cooper.

[Billy]

I'm fascinated by the use of molasses. How does that work?

[ctwomey]

I'm fascinated by the use of molasses. How does that work?

It starts fermenting and consumes the iron oxide but doesn't touch the iron itself. Any metal has to be grease and paint free, but if there is paint it's not too bad because the chances are it was protecting the original metal. Needs to be left for min of two weeks with some agitation each week.

It's far more environmentally friendly compared with hot caustic soda baths. Once it's finished you could pore it on your lawn as a fertiliser (haven't tried that yet). Supposedly it can get very smelly but the only smell I detected was the same smell as beer fermenting.

[ctwomey]

While in lockdown and waiting for the block and cylinder head to come back from the machine shop, thought I would start on the gear box.

Stripped it down completely and have it soaking in a water based heavy duty cleaner to remove all the oil and grease, then going to send the aluminium parts off to be vapour blasted.

The first motion shaft outer bearing shell was easy enough to get out, but the outer idler bearing was a nightmare to get out. Tore out the inner needle bearings and made a steel plate to pull it out.

The gears themselves look very good. No damage. I will still replace the layshaft and needle bearings plus the inner 1st motion shaft needle bearing. The two main bearings look really good and I will keep those. Idlers bearings and outer 1st motion shaft bearings will be replaced too.

[ctwomey]

Managed to get the gearbox pretty clean before it went off to get vapour blasted. I used water-based cleaners as I am trying to be as environmental friendly as possible. A long soak in a citric based water bath loosened up some of the worst grime I have ever seen.

However the difference before and after the vapour blasting is unbelievable. Looking forward to assembling the gears.

I know we are in lockdown but I used DPD to send the gearbox casings to the vapour blasters. The courier companies are doing a tremendous job at the moment during this pandemic. Waiting for a delivery from minispares this Tuesday/Wednesday and I can start the reassembly.

Some of the clearances such as the layshaft, main double bearing, idler gear, diff and primary gear end float I won't be able to measure until I have it partially assembled. Will probably require a follow up order of shims etc.

[ctwomey]

Got an order from minispares today. Started rebuilding the main shaft with new synchro baulk rings, springs and ball bearings.

This gearbox is a mix of A+ parts and original mini gear ratios. It's the DAM2886 casing with A+ layshaft and a four bolt retaining plate and 18mm main shaft. The drop gears are A+
(29/27/29) but the main shaft gears are original mini so they don't have the single grove on the helical gears. I think these mixed boxes were only available from 1979 - 1981 before BL moved over to the A+ gears.

Assembled a X-Pin diff with the output shafts and the 62 teeth crown wheel, so this box has a 3.44 final drive too.

Accidentally left the old fibre washer on the output shaft and couldn't get the thrust block on as it was too tight but quickly realised my mistake. X-Pin has very tight tolerances. On the old diff the pin was quite worn even for a low powered 998 with only 36K miles on the clock. They are not really fit for purpose.

Having stuff to do at the moment is a great distraction. Hopefully the vapour blasted casing parts will arrive in the next couple of days and I can complete 95% of the gearbox.

[The Marcos Graveyard]

Going great guns.

[ctwomey]

Started the assembly of the gearbox. So nice to be working with clean parts. The efforts to get them cleaned was worth it.

I did notice that two of the bearings I bought (1 x smaller layshaft, 1 x 1st motion shaft) were of dubious origin, so have decided to reorder those from another source and ensure they are the genuine ones. The other bearing I bought (1 x bigger layshaft) was an INA needle bearing so that is fine.

I also cleaned out all the threads with a finishing tap. Even after all the cleaning, it's amazing how much crud and gunge lodges in those areas.

So assembly will need to hold off for a week while I wait for the new bearings.

I also checked the endfloat of the primary gear after the new retaining ring and c-lip arrived. Now in spec with exactly 0.004" end float. The movement on the dial gauge was 0.10mm.

[DaveC]

Excellent work!

[woody]

Great work.
Yes I heard about those bearings

[ctwomey]

Some progress on the engine over the last couple of weeks. Finally got the block and cylinder back from the machine shop.

So started with a deep clean after the machining using a combination of Mr Muscle Oven Cleaner (wear a mask) and power washer followed by a quick high temp drying (80C) in the oven to quickly dry off the water.

Painted the cylinder head and block a nice Ford Dark Blue from Eastwoods. Original block colour was black over the 998 baked in yellow. Both horrible colours.

I then cleaned all the threads on the cylinder head and block, it's amazing how much crud still resides in there after a deep clean.

Installed the valves that were also lapped by the machine shop with 160lb double springs that will be much better than the light weight original springs. I also decided to assemble the rest of the head just to see how it looks - super nice! Still need to measure the compression ratio so some ancillaries will need to come off at that point.

I started the assemble of the crank, double checking the bearing clearances using Plastigauge. Spot on clearance with about 0.002" - 0.0025". I also checked the crank end float which is about 0.075mm so around 0.003".

I also took the opportunity during the warm weather to bring the body shell outside and give it a complete power wash. The bright sunlight dried it off really quickly. At least I can see a bit more now of what has to be done on the shell.

Next week I have to balance the pistons and build a balancer for the conrods. Plus finish the assembly of the gearbox now that the bearings have arrived.

[The Marcos Graveyard]

Wonder what Mags would say if I put engine parts in the oven

[ctwomey]

Wonder what Mags would say if I put engine parts in the oven

The block was super clean, no dirt of any kind. It was purely to help the water evaporate and warm it up for painting. Certainly wouldn't put anything with oil in there are even worse something requiring powder coating

[ctwomey]

Some progress on the gearbox over the last few days.

Installed a central oil pickup pipe.

Installed new idler gear bearing in the gearbox casing along with new bearings in the transfer case for the idler gear and 1st motion shaft. Only used quality bearings here.

Checked the end float on the idler, was originally measured at 0.005" but I had a spare shim from another A+ gearbox that got the end float down to 0.0035".

[ctwomey]

Time to check the diff preload. As this is a new X-pin diff the old preload will not be valid so I will need to remeasure. Plus given the Haynes manual assumes a certain gasket thickness too, those instructions will be not valid either.

So I have offered up the two end covers with gaskets and will use that as my starting point.

I have retained the original thrust type bearings as they were perfect so these require 0.004" preload. With 2 x 0.010" shims added I still have a gap of 0.008" between the bearing and the shim, can't fit a 0.009" feeler gauge in. So for the 0.004" preload I will need 0.012" of additional shims to get there, which I will need to order.

[ctwomey]

Some progress on the engine this week. Balanced the pistons and conrods. The conrods were balanced end to end. Overall the little end including the piston is now within 0.1 gram. And the conrods overall are within 0.5 gram. Made my own conrod balancer and was able to get consistent measurements which were double checked multiple times.

Measured the cylinder head combustion chamber volume. All three are within 0.1 cc of each other. I used water with a food dye. Had to tilt the head up to get the air bubble to come to the hole in the perspex.

Installed the pistons too, using plenty of assemble lube. Horrible stuff as it is so sticky like strawberry jam. Crank is rotating around without any issues.

Used a DTI to measure the piston to deck clearances on all four pistons to get a final reading for the compression. Quite a bit of variance across the 4 pistons (0.28, 0.22, 0.26, 0.37) Given the block was decked this can only be down to manufacturing inaccuracies in the stroke of the crank.

Anyway the compression ratio for all four cylinders are coming in at (9.62, 9.68, 9.65, 9.53) which for a road car is just fine. My target was to not go over 9.75 as the fuels available now are not as high in octane as they were in the '80s.

Some parts arriving next week so I can complete the gearbox assembly.

[ctwomey]

Timing in the camshaft this weekend. Decided to leave the cam setup as a simplex with A+ tensioner, however I am using one of those non-stretch chains from IWIS along with a new tensioner. Plus if you add a duplex it tends to be noisier and the A+ cover also needs modifying to make it fit. I am using standard rockers with 160lbs springs in the cylinder head so I don't need the extra strength of a duplex.

So after installing the chain I used one of those Kent Cams vernier discs along with a DTI to identify TDC.

After installing a cam follower for piston 1 inlet valve I took a reading of about 0.10mm before and after max lift on the cam lobe

(101.5 degrees + 121.5 degrees) / 2 = 111.5 degrees which is out by between 4 - 5 degrees of the spec of the cam (106-108). So I need to order a 5 degree offset woodruff key to correct the timing.