Rebore time

[revingtosh]

OK - ive whipped the head off the mini today, and it would appear that the bores are scored quite badly :-(

The bores measure 73.00 mm, so what options are available to me on the rebore front?
If a rebore is possible, what crank mods are needed?

Can anyone recommend a decent engineering shop near Liverpool?

Cheers,

Mike

[Mini_Lund]

revingtosh said:

OK - ive whipped the head off the mini today, and it would appear that the bores are scored quite badly :-(

The bores measure 73.00 mm, so what options are available to me on the rebore front?
If a rebore is possible, what crank mods are needed?

Can anyone recommend a decent engineering shop near Liverpool?

Cheers,

Mike

Hi Mike, are you in Liverpool or on the Wirral? Birkenhead engines seem the obvious choice if you live over on the Wirral. I used them to get my cylinder head skimmed;

http://www.yell.com/listings/DoFindListings/123836...

Tom

[revingtosh]

I live in Widnes mate.

Is any amount of scoring to the bores completely unacceptable? Is it possible to get away without a rebore?

It is quite smokey when cold, but i put that down to the 20/50 oil which im using. Ive also noticed that when the engine is hot, the idle speed is quite high, could this be down to the oil passing by the rings and given extra compression?

I would consider buying a full engine off fleabay, but they rarely come with receipts to prove the spec so im dubious.

Does anyone have anything tasty on here for sale? I would even consider a 16v Red Top or similar.

Mike

[Snake the Sniper]

Are you able to take a pic of the bores? When you say they are scratched, is it a fairly regular cross hatch type scratch? It may be what's left of the original honing if so. If not, you may get away with just a re-hone and new rings. If it's heavily scratched, then you may well need to overbore and get new rings and pistons.

oh, are you sure it's 73.00mm? And not 73.5mm? 73.5mm is the standard bore for a 1380cc engine.

[revingtosh]

Well the car was sold as a 1380, but i used my brand new digital vernier to measure up.

I will have another look with my old mechanical vernier and let you know.

Thanks again,

Mike

[Snake the Sniper]

Beware though, you may be measuring the ridge at the top of the bore were carbon builds up, rather than the true bore diameter. If it is 73.5mm, then you can still over bore it as long as it has been offset bored to get to 1380cc. A 74mm bore will give 1399cc, and you can go to 74.7mm which will give 1426cc. Although I'd be be tempted to just get another engine and start over. Mine might be for sale soon, it's only done 4,000 miles since it was built, but it would probably need a refresh as its been stood for roughly 2 years now. It's a 1338cc shot stroke engine. Nice and revvy, but not very torquey as a result.

[Dino42]

revingtosh said:

Well the car was sold as a 1380, but i used my brand new digital vernier to measure up.

I will have another look with my old mechanical vernier and let you know.

Thanks again,

Mike

I wouldn't trust a vernier to give you an accurate bore size, you really need a set of bore guages (effectively an internal micrometer with three arms)
It's most likely it's already at 73.5mm. 73mm pistons (to give 1360cc) are relatively new and cost more than 73.5mm ones.

Also as mentioned you shouldn't measure at the top of the bore, you need to measure 1/3 to 1/2 way down and not just in one direction.
Any decent machine shop will measure it for you and give you an idea if any wear/damage is acceptable.

[Dino42]

revingtosh said:

...It is quite smokey when cold, but i put that down to the 20/50 oil which im using. ...
.... Ive also noticed that when the engine is hot, the idle speed is quite high, could this be down to the oil passing by the rings and given extra compression?..

Put simply....no! (to both)

Edited by Dino42 on Saturday 27th December 15:39

[Cooperman]

The crank is probably fine, or will be when it's had a grind.
As for the block, personally I would advise you to find a basic 1275 cc block and bore it to +0.060", that's 1330 cc. Use the competitively priced Hepolite 21253 pistons.
Check the existing comp ratio as if it's been to 1380 the combustion chambers may have been enlarged to get the C.R. correct for a large engine. You should aim for about 10.2:1 and once the engine is to bits I can tell you how to meqasure it using just a 10 cc shrynge from Boots-the-Chemist and a piece of flat perspex sheet.
You should be able to find an old Metro block for not much money and perhaps someone on here has one that's only been out to a max of +0.040".
Do youself a spec sheet before you start so that you end up with an engine which suits your needs. Discuss the spec on here if you wish, we'll all help.

[revingtosh]

Yes, the hunt for an engine is now on!

The options are:-

1) Buy an MG Metro engine / box / ancillaries from a Mini breakers in Warrington. He wants £450 for the lot with a 30 day warranty.

2) Go down the 2 Litre 16v route. Allspeed subframe, vauxhall redtop etc.

3) Find a good complete tasty second hand lump from a forum such as this one.

4) Buyer a stter and rebuild the lot.

Just so you know, i already have the following parts laying about:-

Weber45
Oselli Head
Piper285 Magnum 2 Camshaft
Maniflow System.

Please let me know what you think.

Also, if anyone has something suitable for sale, please let me know. Please PM me, or emither me at [e-mail]

Thanks a million

Mike

[Snake the Sniper]

You have an e-mail about my engine, although since it's quite long it basically says rebuild a stock engine! It'll be cheaper.