24 replies to this topic

[Cooperman]

Yes, those are the maximum lift figures for the 286.

For a road engine the problem with the 286, besides the narrow power and torque band, is that it produces its maximum power at 6400 rpm in a 1275 and that means to make the cam work as it should you would be using 6800 rpm which will cause more rapid engine wear. It is great in a low geared rally car where acceleration is most important and cruising speed unimportant, but for the road it is not good. In fact on the road a car with a 286 is likely to be slower unless it is revved to almost 7000 rpm in all the gears. Personally I wouldn't risk those sort of revs unless the block had a centre main bearing strap and had fully balanced rods, crank assembly and pistons.

1 mm deck to piston crown really is a bit too much, especially with those deep dish pistons. It is important to know what pistons are fitted. If they are low-grade ones then they won't take high revs and/or high compression. Ideally a CR of around 10:1 would be best.

If you have a fairly mild cam, then skim the head to give something over about 9.5:1. If it has a 286 then best advice is to strip & rebuild with a milder cam and 21253 pistons at +0.040" (1310 cc).

[Jukesr]

Thanks Cooperman you talk a lot of sense Pal.

 

I will check the Measurements and get back to you, but I need to bye a dial gage and mag mount to get them. 

 

fingers crossed for a none 286 cam then ha-ha :)  

 

would a 266 be classed as mild ?

[Cooperman]

IMHO the 266 is one of the best cams ever for a road Mini. It gives maximum power at 5700 rpm and strong torque from around 3200 rpm. It will pull cleanly from about 2000 rpm right up to over 6000 rpm. It is very similar to the MG Metro cam.

If used with a gas-flowed head, around 10.2:1 CR, an HIF44 carb on a good alloy manifold and an LCB exhaust with a 1.75" exhaust system it performs very well indeed.

It can pull with a 3.1:1 FDR and I've used a 266 with a 3.44:1 FDR and standard gear ratios and it was superb on the road.

[Jukesr]

Right ok

 

o and I have all of the above parts already fitted :)

 

so what cam would be best with my CR of 9.3:1 ?? because that is the best CR im going to get without changing pistons and stuff, just so when I get the Cam lift figures I can see if its close to the right cam.

[Cooperman]

The Kent 266 or the MG Metro cams will both work well. There are other choices like the SW5, but I can't personally recommend them as I've not worked with them. The 266 is particularly nice in a road Mini.

[gazza82]

And hopefully a 1330 road going Midget engine...

[Cooperman]

It will be superb in a Midget which, I'm sure, is lighter than a Mini by a few Kg.

I built an engine for a Frog-Eye Sprite based on an 1098 engine from a Minor.

It was bored to 1130 cc with flat top pistons, a 266 cam, twin H4's, light flywheel, low FDR and a 12G295 flowed head at 10.3:1 CR.

It went really well and so much better than the original 948 Sprite. The owner used it for historic motor sport and it we used the 1098 engine because it was a period modification, which the 1275 would not have been. Used the 266 cam to get best power without having to use over 6000 rpm through the gears due to the crankshaft limitations with the 1098. The mid-range torque was fantastic too.

[Jukesr]

Just done some me serpents of the cam lift it and bad news on my part,
It's got 8.21mm on the intake and 8.61 on the exhaust, so it closer to the 296 then the 286 like the engine needs to come out

The pistons have TRW-175-9797-1 / + .03 / 71.35 if you want to know.

Thanks for your help Cooperman.

[Jukesr]

*That's measurements not serpents....

[Cooperman]

I think the pistons are for a turbo-charged engine, but can't be sure. If they are then they are a fairly heavy piston for mid-range revs.

 

You most definitely need to take that cam out as it will be very poor for road use. Also, if using a cam like that you need to be sure the engine's bottom end is suitable for the very high revs of up to 7000 rpm. For that you need a very thorough build with top quality bolts, a main bearing strap and full balancing.

 

Best bet is to strip it out and build a 1310 cc engine with 21253 pistons. Do your CR calcs based on an 8.4 cc piston dish and the block deck skimmed after a trial build to give a piston to deck level within 0.004" (I work in imperial as that's how the Mini was designed). Then with a 266 cam it will be a joy to drive on the roads.