Hi everyone,

Updated goal/plan/progress - 2019
1098 block bored +080 with flat top pistons
12G202 head modified by GR
RE266 cam
Crack checked + reground 1098 crank
4 synchro remote gearbox - standard ratio, 3.44 diff, pot joints, magic wand shifter

I've recently picked up three engines that I'd like to pull apart and see how they work and rebuild one.


First engine is a 998 (99H34AJH) with a 12G295 head, 22G1832 rod change gearbox with pot joints
Second engine is a 998 (99H860AJH) with a 12G202 head, rod change gearbox with pot joints
Third engine is a 1098 (10YJUH) with a 12A1456 head, rod change gearbox with pot joints.

Currently the car has a 998 (9YATaH) with a 12A1456 head, remote gearbox and early rubber cross driveshafts, and front drum brakes. It is stock apart from an electronic distributor. It was last rebuilt in 1989 and still runs fine, but it won't last forever, and it's not particularly fast. I've also picked up a clean single HS4.

I've had a little experience with rebuilding an engine. I did a simple rebuild - rings, bearings, gaskets, clean up and paint - on a Mazda TC engine for my last car. It was single overhead cam and RWD, so a bit different in configuration to the mini one. There were essentially no aftermarket or performance options for it, so I'd like to do a few with the A-Series engines I've got now.

What I'd like at the end is a small block, 1098 crank, 12G295 head, remote gearbox, pot joints, and to do as much myself as I can. Seeing as the 1098 engine started life with 50hp at the crank, I'd be happy with 50hp at the wheels after the modifications (that's probably double what I've got now). I'd probably do some discs at around the same time.

A couple of questions at the moment:
1) If I went for the 1098 crank and some flat top pistons with the 295 head, what size should the combustion chamber need to be? I've tried to measure it with a syringe and ended up with about 28cc. This one looks to have been skimmed about 2mm and had the chambers opened up?

(Before)


2) If I get a spare remote gearbox can I swap the pot joints over? I've also read that the gearsets can be swapped over, but the selectors need to stay with the remote?

Cheers, Tim

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yes, you can swap the pot joints over

those rod change gearsets would only be compatible with a 4 syncho remote gearbox, being a 22G1128 case. I assume by your current engine number you have a deluxe with a 22G68 case, being 3 synchro and not compatible

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did I tell you that I won a trophy?

As Simon said you need a 4 synchro remote box. The gearset in it is already the same as your rodchange one (except reverse gear fork slot).
These boxes were used in Mini K, Mk2S, 1098 Clubby & Moke, from 1969-1973 approx.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Ok thanks. Yep, the current one is only a 3 synchro one. I haven't worked out the diff ratio yet in these rod change boxes..

Thanks. I guess it comes down to what kind of 4 synchro remote casing I can get, and if it has gears in it.

I've been pulling the first one to pieces during the last week. If it wasn't left out in the weather it would have been quite nice. The bores are nice and smooth except for where the pistons had been sitting, where there is a bit of rust. Surprisingly I didn't really have any issues with stuck bolts or parts, even the flywheel came off without any dramas. The gearbox was full of a lovely milky water oil mix, but the gears look nice under all the goop and don't look chipped. The only stuck part so far is one piston that won't budge out of the engine block. I haven't been able to find any markings or identification on the cam as to if it is anything different to stock.

I'm wondering how well it would have run too? It has a 998 crank (21A1451) with normal dished pistons (M2039) and a big volume cylinder head, so it would have had a really low compression ratio?

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I bought an engine once where a piston wouldn't come out of the block. I tried diesel in it, left it for weeks but no joy.
So I pulled the crank, then knocked the piston down the bore a bit with a block of wood.
Then I used the die grinder with a 40mm stone on it to get rid of the rust up the bore. It came out fine then.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I might have to get some diesel for situations like this. I have given it a bit of a knock with a hammer already but it hasn't budged. It's right at the top of the block already so it doesn't have far to go..

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Vinegar will probably work better than diesel.

My father has had success with a molasses mix as well.

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1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt

I had tried molasses mix for 3 weeks, it didn't work. Probably because of oil etc in the bores.
It worked a treat in the water jacket though, after I bolted a head on then stood on end and filled it thru the water pump opening. After 3 weeks with some periodic stirring, it was spotless...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I have had a lot of success freeing up rusted/seized parts with vinegar.

the piston is rooted and the block will need boring - just beat it out - look at it as therapy

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did I tell you that I won a trophy?

I might get a big bottle of vinegar then. I've given a few big beatings with the hammer already, hopefully it gives up soon

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I've had some movement from the piston today when I popped into the garage briefly. I'll be able to pop it out next time I'm in there.

Is there any benefit to swapping an engine with the subframe still attached? I'm considering getting another subframe and building it up with new bushes and cones and other bits. Are all the dry subframes the same or did they change them over time?

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Subframes are the same, swapping the entire subby means you'll probably need a new wheel alignment due to the tie rod ends/steering arms and tie rods but all the new rubbers may also push things out a bit and you'll need to bleed the brakes. But that also lets you paint and rebuild everything.
Some people prefer to remove an engine with the subframe others prefer to take it out the top.

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Respect mine and I'll respect yours.

That's good to know. More than likely I need a wheel alignment now anyway, and I might put some nice adjustable bits on the new subframe and build it all up. It would probably be the best time to upgrade the brakes too..

The first 998 I pulled apart looks surprisingly nice inside now I have something to compare it to. The inside of the gearbox and inside the engine looked almost good enough to just clean and put back together. Here is the nice shiny crank out of the 998.

I had a go pulling the 1098 engine apart last night. Unlike the first engine, this one contained only water in the sump and no oil. The alloy clutch/flywheel housing was covered in white corrosion, and inside the sump was orange and crusty.

The crankshaft was equally crusty, but strangely this engine would turn over and the pistons weren't too stuck.


I might need to keep looking for another 1098 crank...

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