21 replies to this topic

[Cooperman]

I always use the Kent 286 in rally cars with a 3.9:1 FDR and a SC CR gear set. But when on road sections it is a bit of a pig really. The power is strong from about 4500 up to around 6800 rpm, but for a road car that is really too high.

I have used the 266 and the similar MG-Metro cams in road Minis to good effect and I did build an Endurance Rally 1330 cc 1990 Cooper which had to have standard engine, so the MG cam was fitted. The carefully assembled and blueprinted engine, with its single HIF44 gave 84 bhp at 5700 on Mass Motorsport's RR, but most impressive was the torque at around 3500 rpm. I used a 3.44:1 FDR as I reckoned I could get away with that at scrutineering (standard gearbox specified).

On an Innocenti I had, now sold, I used the Cooper 'S' 510 cam and for normal road driving it was great and just like the original Cooper 'S'.

My own belief is that a lot of people 'over-cam' their engines and then have to rev them quite high to get them to go, whereas a softer cam with a well built engine which 'breathes well' via a good head and inlet/exhaust system can be so much more satisfying on the road.

A Mini is never going to be a 'fast road car' anymore, so it can often be best to build a nice 'friendly' engine and enjoy the 'classic retro' motoring that gives.

[carbon]

As my oil pressure is low and don't know how long it's gonna survive im looking at building a new engine with a bit more power


I've got a 1275 sitting here but would like advice on what bore and Pistons gear ratio and diff to buy
I've got a hiff44 already and the car will be used as a town car with some distances to shows via motorway to would like it to cope with the motorway

I'm thinking 1330 for reliability but if you engine builders could help me decide as my Knolledge is limited which bore and Pistons etc to go for , I know head is a easy thing that can be upgraded in the future

 

Before boring out to 1293 would be worth checking what state the bores are in, as it may not need a rebore.

 

I'm currently rebuilding an old (early 70's) 1275 unit and this just needed a hone and new rings.

[gazza82]

If the oil pressure is low it's more likely to be the bearings than cylinders. Have you changed the oil recently and used a good quality 20/50?

[spritey]

I'm using 20/50 millers oil , and I've got a spare engine which is what I'm wanting to build and then just swap the engines over ( oil pressure is low and the gearbox is on its way out in the one in the car at the moment ) my plan from the start was to build something with a bit more power than standard to put up with motor ways and be a bit faster , 1293 was what I'm thinking but I'm also thinking going to 1330 not hundred percent sure which is gonna be most reliable , I'm not to bothered about not being able to bore it again just wanting to build something that I can add to , so build the short block with cam then afterwards I will do the head etc as money is limited , it's a car I've had for 10 years and will be keeping so don't want to make a mistake , I've read all your comments and took them in and it's really helped me understand , only the measuring setting cr is only thing I don't fully understand ,

[gazza82]

The only advantage of going up on 20thou increments is if anything untoward happens you have two more rebores before you have to sleeve or think about larger offset bores.

 

I don't know whether there would be a great deal of extra bhp from a 1330 over a 1293 or 1301 ... but it preserves a block for longer .. (I'm building a 1330 Spridget engine and they are rarer than Minis and getting expensive .. my block was already at 1330 so that's my starting point).

 

The main gains are going to be in the head/porting and cam .. and carbs/exhaust.

 

 

For CR I use this .. http://www.csgnetwor...m/compcalc.html .. if you assume a standard 1275/12G940 head is 21.4cc in the combustion chambers, you have a starting point. Measure the depth of yours to see if it's been skimmed. It should be 2.75" if standard.

Edited by gazza82, 22 May 2015 - 10:54 AM.

[racingbob]

As above, bore to the next possible oversize.

Use 21253 pistons.

Use 35.6 mm inlet valves and 29.5 mm exhausts in a head which has been slightly cleaned up in terms of gas flow. Measure, calculate and set the compression ratio to between 10:1 & 10.3:1.

An MG Metro camshaft is very nice to drive with combined with an LCB ex. manifold and 1.75" Maniflow exhaust system. The inlet manifold should be an allow one cleaned and matched to the head ports.

Use new cam followers and new oil pump with a re-ground crankshaft and new main & big end bearings.

Set crankshaft end float to between 0.002" & 0.004".

Time the cam in very accurately using either vernier sprockets or offset woodruff keys and fit a duplex timing chain.

Fit an Aldon 'Yellow' distributor.

Usually good to fit a new water pump.

Use a BK450 head gasket.

Assemble it very accurately and carefully.

 

I hope this helps.

this is virtualy exactly as my engine without the aldon yellow

 

just the basic mg metro dizzy

 

but my engine is balanced, excellent performance all round

 

very happy

 

I have 3.4 diff but you may want the 3.1 or a 3.2

 

flywheel doesn't need lightening just leave as is

 

but I have the pre verto so maybe yours does a bit

[Dusky]

I always liked a bit of a heavier flywheel ( just standard verto) with longer duration cams. Takes out the lumpyness