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1275 Engine Rebuild


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#16 MiniBGT

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Posted 13 October 2018 - 07:18 AM

The 'Ultimate Mini Builder' DVD is a very good guide.  Although it takes you through building a race engine it does have some very good tips and techniques.



#17 Bat

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Posted 13 October 2018 - 07:28 AM

Hi,

There's lots of different ways to get what you want.

First part of building an engine is planning and researching.

Second I would say is work out your budget.

How much you can do yourself or learn to do will make your budget go further.

 

I would recommend getting mappable ignition, that means you bin your clock work dizzy and move into the modern world of ECUs.

I found it means you can run a 285 cam and drive smoothly through town at 30mph in forth, and floor it when you see the nat. speed limit sign and soon be exceeding it without changing gear! Something a dizzy will never be able to do.

 

Watch for bulkhead clearance on early cars with a hif44.

 

Cheers  :proud:



#18 Will96

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Posted 13 October 2018 - 06:33 PM

Hi magneto, it's a 1275 I'm redoing, 998 is currently in my car. Thank you all for the responses, I'm finding that each response I'm understanding a bit more about the different aspects of the build. In terms of the head, obviously cost effectiveness plays a role in this, I haven't got over a grand to throw at one element, my question is would changes to the existing head be more sensible when this is essentially going to be a road car and not a track busting hell beast



#19 Will96

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Posted 25 October 2018 - 02:33 PM

Following on from this conversation I've had a look into some parts and it's confused me a little bit. From what I'm aware my engine is an A+ 1275 (found out from the crank cam6232 as the engine number has rusted to a point it's unreadable) and I thought it was a verto clutch and flywheel but when I had this in the engine it never fit properly onto he end of the crank and the clutch would continuously slip, which made me doubtful. Then I saw minispares and similar sites don't do flywheels for verto clutches. If anyone could shed some light that would be appreciated. Also I was wondering whether "performance" push rods or lightened cam followers make any noticeable difference to the engine. Thanks



#20 Retroman

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Posted 26 October 2018 - 12:13 AM

Ok

Not 100% sure what you are meaning about the flywheel never fitting properly, if that is the case then the crank may be toast

 

The flywheel is bolted tightly to the taper on the end of the crankshaft ( or it should be) and never move

 

If it was just clutch slip thats entirely different and will be a lot cheaper to sort out.

 

Minispares do sell verto flywheels I have just fitted a lightened one, which uprates the clutch pressure at the same time.

 

As you are not after a flying machine don't waste your money on pushrods or lightened cam followers

 

Your priority needs to be a good quality build using a combination of good quality parts.

 

As its just a road engine with some added go, you need a good head which has been mentioned

 

Along with a decent fast road cam MD266 Or MG metro sort of timing / lift will work well

 

Compression ratio needs to be considered, capacities measured and maybe the head and or block skimmed as needed

 

Some other good quality components such as an Iwis timing chain, known followers

 

Its also important that ALL the bearing surfaces in the engine are perfect, crank reground etc

 

The end float on the crank, primary gear and idler gears should also be optimised.

 

There are lots of other things to do and consider, including carb, an HIF 44 will be best

 

First decision needs to be how many CC's do you want ? 

 

A + .060" overbore to 1330 is plenty and can give you twice the power of a standard 998

 

2nd decision is down to budget...as pistons can vary from less than 200 to about 450 quid

 

Its important that the parts work together and that its built well otherwise you can end up in a mess

 

PM me if you want and I can beat most on price and quality



#21 Will96

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Posted 26 October 2018 - 06:49 AM

That's all very helpful thank you. I might take you up on that offer once I've worked out what I'm actually doing. To elaborate on the flywheel and crank I think you may have been right with it being toast. The end of the shaft has been chewed up (an issue I noticed while putting it together but didn't think much of it) and it's almost as if the diameter of the hole in the centre of the flywheel was smaller than the shaft. So when fitted the locking nut didn't sit reach the end of the crank shaft.

#22 Retroman

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Posted 28 October 2018 - 03:20 PM

If the crank was even slightly chewed to start with it will be worse now.

 

Both the taper on the crank tail and in the flywheel need to be mint, as it handles all the drive from the engine

 

I always lap flywheels onto the crank with fine grinding paste, so any high spots are removed and both surfaces fit to each other.

 

Any high spots mean the whole energy is concentrated there and it ends up friction welding as it frets back and forth

 

J7BYbki.jpg



#23 Will96

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Posted 04 November 2018 - 10:56 PM

Thank you for the info. I've ended up buying a new crank and as soon as I remember I'll upload a photo and you'll be able to see the extent of how chewed up the end is. On yet another tangent, in the process of cleaning the engine I'm wanting to strip the existing pain job back to start again with a decent surface. Are there any paint strippers of general chemicals that do a good enough job that could be bought from general UK DIY or automotive shops. Or am I better taking to Amazon and buying some of the VHT spray that the internet seems to do nothing but rave about. Thanks :)

#24 Will96

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Posted 14 November 2018 - 11:15 AM

As promised, one photo of a pretty mangled crank shaft

#25 Will96

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Posted 14 November 2018 - 11:17 AM

Try again

Attached Files



#26 Retroman

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Posted 14 November 2018 - 11:34 AM

holy sh1 t

 

Certainly needs the new crank

 

If its brand spanking new its worth having a machine shop polish the journals, make sure its straight, the fillet radii are all good

 

make sure all the oil drillings are 'opened out' rather than just a straight sharp edged drill hole

 

Lap the flywheel on with grinding paste

 

As the crank tail is so mangled I would be changing the flywheel too, the taper in there can't be good



#27 gazza82

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Posted 14 November 2018 - 01:33 PM



On yet another tangent, in the process of cleaning the engine I'm wanting to strip the existing pain job back to start again with a decent surface. Are there any paint strippers of general chemicals that do a good enough job that could be bought from general UK DIY or automotive shops.

 

I got most off with an old can of Nitromors .. not the water-based carp they sell now .. but in the end to get back to bare metal needed wire brushes .. most attached to a drill!  But I also know my engine had been repainted before .. I know the person I bought it off.

 

Below is my attempt .. tin of engine paint and several brushes!

 

Attached File  1330block_20140504.jpg   77.99K   4 downloads



#28 Will96

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Posted 16 November 2018 - 11:25 AM

With the crank I've bought a second hand block that (I was told) has been bored out +060 complete with pistons and a crank that was in much better condition than mine, if anyone knows I wouldn't mine knowing the mm of he cylinders to check that it's all in order. But apparently the engine had been running and was sold for a gearbox issue which I already have so that's all good. The paint on it looks as though it's been applied with a stick, hence wanting to strip he paint. So I'll try with some nitro. I've managed to peel of a large amount of paint with finger nails and a Stanley blade so it's just going to be for tidying up and making a proper job of it. Thank you for the suggestion

#29 Will96

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Posted 16 November 2018 - 11:46 AM

Additionally to the diameter of the cylinders, if anyone knows the diameter of big end surfaces on the crankshaft so I could check whether I need to buy oversized big end bearings it would be much appreciated

#30 Will96

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Posted 11 January 2019 - 01:28 PM

Update:

Well it turns out the engine block I've purchased is actually a 1380, complete with (What I believe are) Omega pistons. Upon inspection of the main bearings and big end bearings that came with everything, they were stamped as standards, which makes me think the crank hasn't been machined, which has impressed me as there are no causes for concern over the journals/bearing seats, and whilst the bearings are in poor condition from being out of the engine and not protected properly, they have no signs of scoring or sufficient damage, so thinking of continuing with standard bearings and not machining the crank where it isn't necessary. 

 

In terms of the parts I'm thinking of using to rebuild this engine, I'm still only after a fast road setup at relatively low cost, and I do plan on making upgrades in time as funds come available for elements which can be swapped out while the engine is in use. In terms of the components I'm thinking of upgrading now, I was considering an uprated oil pump and maybe a fast road cam, then beyond that I currently have a simplex timing assembly and have been researching on the benefits of upgrading to duplex, but I'm a little uncertain on whether to stick with simplex and tensioner, duplex and tensioner, or just duplex. If anyone has any recommendations for additional or alternative components then I'm welcome to suggestions  :proud:






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