7 replies to this topic

[Gillybobs]

After a break from my project mini im hoping to get back on With it this winter .
It's a 1993 Italian job which has covered 78000 miles so I'm thinking the engine will be past its best.
My father has said he will help me rebuild the engine as he worked at Coldwell engineering in sheffield restoring vintage Rolls Royces so hopefully an A+ engine shouldn't be to difficult for him!

The engine number starts 12A2BG03 which the guesswork's engine decoder tells me it's a 1275 ,9.4:1 compression ratio. Hif 38 carb .3.1 final drive .

I plan to fit a stage 1 kit.
So my question is , Do I rebuild the engine as a standard spec or are there any little tweaks i could do to "pep" the engine up a bit? I'm wondering about raising comp ratio maybe a MG metro cam or similar
I've not got a mega bucks budget and I want build a reliable drivable car to take my wife and sons to shows and maybe be take the car out for a blast now and again at weekends .
I,d welcome people's thoughts on what spec to build the engine .
Thanks in advance !

[timmy850]

It all depends on how much work it all needs when you strip the engine. If you need to replace a part, you may as well replace it with something better than standard if you want a bit more power

If the block needs a rebore to the next size up, consider putting in some higher compression pistons. 

If the head needs some work done to it, consider an exchange performance head or getting yours rebuilt (larger valves, skim etc)

The cam is easy enough to upgrade with the engine apart

You'll need to replace all the normal gear - gaskets, bearings, oil pump etc

It might also be worth getting a HIF44 

 

Then again, if the cylinder bore and head are in good condition a freshly rebuilt standard engine with a stage one kit will get you going nicely and keep the cost down.

 

If you don't do much highway driving you could also consider a shorter final drive. A 3.44 will get the car going a bit quicker, the downside will be more rpm at highway speeds. 

[Gillybobs]

So my next question whats a sensible compression ratio to aim for?
Also would a hif 44 make a big difference? Or would that just be at the top end with high revs?

[Spider]

The CR will depend of what fuel you are happy to use, the camshaft and how you time it in.

 

Size the carb to the expected HP output of the engine, though slightly smaller is usually better than slightly too big for road use.

[Gillybobs]

I would be running standard 95 ron unleaded .
Was thinking possibly this cam .
https://shop.aseries...-series-engine/

[Cooperman]

I would recommend something like the following:

 

MG Metro head with a small amount of gas-flowing in the inlet and exhaust tracts and in the chambers, with the valve guide bosses being ground back to allow more flow (lots about this in Vizard's book - Tuning the A-Series Engine (get a copy!)..

Use P21253 pistons and deck the block to bring the top of the pistons to within around 0.004" of the deck level.

Set the compression ratio at around 10:1 by measuring, calculating and skimming the head (there is lots about how to do this on here if you search).

Use an HIF44 carb and a good alloy inlet manifold. Clean up the inside of the manifold to remove the sharp edges.

Skim a bit from the flywheel to lighten it.

Fit an MG Metro or Kent 266 cam. A Mini Spares Evolution 001 might be a good alternative and they come at a sensible price.

Time the cam in accurately using an offset woodruff key of the right offset. Fit a duplex timing chain.

a freeflow exhaust manifold and RC40 exhaust system would be a good match with this spec.

 

As above, a 3.4:1 FDR helps give better acceleration.

 

I hope this helps.

[Gillybobs]

I would recommend something like the following:
 
MG Metro head with a small amount of gas-flowing in the inlet and exhaust tracts and in the chambers, with the valve guide bosses being ground back to allow more flow (lots about this in Vizard's book - Tuning the A-Series Engine (get a copy!)..
Use P21253 pistons and deck the block to bring the top of the pistons to within around 0.004" of the deck level.
Set the compression ratio at around 10:1 by measuring, calculating and skimming the head (there is lots about how to do this on here if you search).
Use an HIF44 carb and a good alloy inlet manifold. Clean up the inside of the manifold to remove the sharp edges.
Skim a bit from the flywheel to lighten it.
Fit an MG Metro or Kent 266 cam. A Mini Spares Evolution 001 might be a good alternative and they come at a sensible price.
Time the cam in accurately using an offset woodruff key of the right offset. Fit a duplex timing chain.
a freeflow exhaust manifold and RC40 exhaust system would be a good match with this spec.
 
As above, a 3.4:1 FDR helps give better acceleration.
 
I hope this helps.

Yes it does!
Got me thinking about an MG metro engine me and my dad rebuilt for my old mini. I bought it locally for £30! I had the crank reground and block rebored to 1293 and if my memory serves me right it ran a C.R 9.75:1 which I would imagine it would have run the same pistons as you have recommend. The engine had had a recon gearbox but it had a real low final drive but I managed to get a 3:1 final drive cheaply . I quite like that as the mini would sit at motorway speeds comfortably and it didn't accelerate too badly as I remember.
If I could build an engine like that is be very happy!

[Turbo Phil]

If you're fitting the MG head with the 1.400" inlet valve, some basic deshrouding of the chamber around the valve and a 30deg back cut on the valve itself will make a decent gain in flow for very little work/cost.


Phil.