20 replies to this topic

[mini-geek]

Can't make my mind up 286 or 276?

I'm running a 1380 with an MED RS cam and I'm not happy just doesn't give me a grin while driving, it's a bit to lazy and sensible. I want something with a bit more poke. but I also don't want to loose too much driveability can anyone help me make my mind up?

[Broomer]

mmm i often have dreams where im drving but not in control of stopping tis really annoying

In my honest oppinion the 286 will be beautiful in your 1380 I ran my 1293 for 10k with a
286 and it gave me a lot of smiles per gallon, and was just about bearable in traffic whilst commuting etc.

[danrock101]

what kind of power is the engine making at the moment? I thought the MED RS cam was more wilder than a 276 surely

[Cooperman]

What is the spec of your cylinder head and carburation? For a 1380 with a really good cam you need 37.5 mm inlet valves and good gas-flowing too. It's no good going to a hotter cam if the head or carbs are not capable of flowing the increased mixture which the cam will allow. In fact, a 1380 probably goes best overall with a slightly milder cam as it has more torque than smaller units and needs good gas-flow at mid-range. A 286 gives max power at 6400 rpm, whatever the engine size, and that is high for a road-going car.

[mini-geek]

What is the spec of your cylinder head and carburation? For a 1380 with a really good cam you need 37.5 mm inlet valves and good gas-flowing too. It's no good going to a hotter cam if the head or carbs are not capable of flowing the increased mixture which the cam will allow. In fact, a 1380 probably goes best overall with a slightly milder cam as it has more torque than smaller units and needs good gas-flow at mid-range. A 286 gives max power at 6400 rpm, whatever the engine size, and that is high for a road-going car.

head is a minisport stg 3 and I have twin HS4s the rest of the engine is more than up to spec.

the RS cam is slightly more mild cam than the 276 going off spec

[Cooperman]

A 276 should be ideal then. I built an A+ to that sort of spec at 1275 cc and it gave 92 bhp at 5800 on the rollers a while back. Was good in traffic too and as the revs were not really needed to go over 6000 rpm it didn't need a centre main bearing strap. I set the CR to 10.5:1 and the head was a Rob Walker Engineering one which is good. I always recommend Rob Walker for cylinder head work and for machining if you are within reach of Witney, Oxon.

[Seb]

i used to run a 276 with my 1380 built by med and was pleased with the results..... although a lack in mini driving experiance i have no comparisons!!

[Cooperman]

There is a lot of uninformed talk about cams, but to clarify things a bit, the cam does not determine the overall power available 'under the graph' so to speak. The overall power is determined by the head, induction system, compression ratio and exhaust system. All the cam really does is to 'position' the available power within a power band and 'release' that available power. In other words, with a good head, carbs and exhaust system, you can have reasonable power over a broad power band for nice drivebility under all conditions, or have the power at a higher maximum figure over a narrower band. It depends on your anticipated and intended use. You can't just change the cam and expect toget more performance. You can change the cam and make the car more suitable for a specific use, such as rallying or hill-climbing, but then you must be changing other components to match that use. For example, a 286 cam with a straight-cut close ratio gearbox and a low final drive, with high CR and very good head will be great for 0 - 60 on a rally test, but will confine the cruising speed to about 60 mph on any sort of main road or motorway.

[josh.evans]

A 276 should be ideal then. I built an A+ to that sort of spec at 1275 cc and it gave 92 bhp at 5800 on the rollers a while back. Was good in traffic too and as the revs were not really needed to go over 6000 rpm it didn't need a centre main bearing strap. I set the CR to 10.5:1 and the head was a Rob Walker Engineering one which is good. I always recommend Rob Walker for cylinder head work and for machining if you are within reach of Witney, Oxon.

Was that from a standard 1275 bore?

[Cooperman]

A 276 should be ideal then. I built an A+ to that sort of spec at 1275 cc and it gave 92 bhp at 5800 on the rollers a while back. Was good in traffic too and as the revs were not really needed to go over 6000 rpm it didn't need a centre main bearing strap. I set the CR to 10.5:1 and the head was a Rob Walker Engineering one which is good. I always recommend Rob Walker for cylinder head work and for machining if you are within reach of Witney, Oxon.

Was that from a standard 1275 bore?

Yes it was.It was a very low-mileage A+ 1275 block which had just 5000 miles from new. I re-built it to give more output, but left the bores unchanged at 1275, which really is all you need if the engine is built accurately. Too many people go for big-bore engines which are rthen not bilt in a professional and optimum manner and wonder why they don't go better. I always say start at 1275 if he bore is still good, then go up in +0.020" incremants until youn reach +0.060, i.e. 1330 cc, then sleeve back to 1275 at next necessary re-bore. that way the block will last 'forever', not be scrap like a 1380 block will when re-boring is needed. Blocks are going to be more and more costly to buy in the future as the 1380 boys scrap them.

[josh.evans]

A 276 should be ideal then. I built an A+ to that sort of spec at 1275 cc and it gave 92 bhp at 5800 on the rollers a while back. Was good in traffic too and as the revs were not really needed to go over 6000 rpm it didn't need a centre main bearing strap. I set the CR to 10.5:1 and the head was a Rob Walker Engineering one which is good. I always recommend Rob Walker for cylinder head work and for machining if you are within reach of Witney, Oxon.

Was that from a standard 1275 bore?

Yes it was.It was a very low-mileage A+ 1275 block which had just 5000 miles from new. I re-built it to give more output, but left the bores unchanged at 1275, which really is all you need if the engine is built accurately. Too many people go for big-bore engines which are rthen not bilt in a professional and optimum manner and wonder why they don't go better. I always say start at 1275 if he bore is still good, then go up in +0.020" incremants until youn reach +0.060, i.e. 1330 cc, then sleeve back to 1275 at next necessary re-bore. that way the block will last 'forever', not be scrap like a 1380 block will when re-boring is needed. Blocks are going to be more and more costly to buy in the future as the 1380 boys scrap them.

Thats very true this year engine and blocks seem to me more and more expensive and its hard to find a good one that hasnt been fidled with.

[danrock101]

I think you would be better off upgrading the head and leaving the cam if it's the mini sport stage 3 head you've got, it's probably the weakest part of your engine in terms of power

[mini-geek]

I think you would be better off upgrading the head and leaving the cam if it's the mini sport stage 3 head you've got, it's probably the weakest part of your engine in terms of power

What the...? did you just make that up in your head? how many engines have you built?

[Cooperman]

I think you would be better off upgrading the head and leaving the cam if it's the mini sport stage 3 head you've got, it's probably the weakest part of your engine in terms of power

What the...? did you just make that up in your head? how many engines have you built?

As keeps on being said on here (who listens?), the expressions Stage 'this or that' means little in reality as different vendors mean different things. What is needed is to know that it's a fully gas-flowed head with whatever size valves and combustion chamber sizes. Then it actually means something. After all, this is a technical part of the forum and sales expressions have little meaning. It is a bit worrying that one company's Stage 3 may be compared with anothers similarly described offering when, in reality, the tech specs are quite different. Let's try to give the correct specifications so that those of us who build a lot of engines can give best advice and try not to use this 'Stage B***s**t' business. Sorry to be blunt about this, but many of us do try to help, so help us to help as well, please.
If the valves are, say, 35.6 mm inlets with, say, 30.5 mm exhausts and the CR is c.10:1 or slightly higher, then a 276 cam would, IMHO, be just what you need to make a super engine which you'll enjoy driving. Build quality is so important too, so do a trial build before final assembly and check everything is good, especially accurate cam timing at, ideally, 2 deg advanced from recommended to allow for initial timing chain stretch.
Good luck with the build project.

[mini-geek]

not sure what your getting at there... but I'm simply saying what head I had a Minisport stg 3 head if I just said stg3 head then that would be stupid but I didn't do that.

anyway MS head spec is 37 in and 29 out mine has since been fitted with rimflow inlet valves this is an engine thats built and giving good figs just not delivering the power how I want it I'm not wanting to change the head untill next winter when it will be a 7 port but the MS head is quite good ok its not a MED race head or what ever but nor was it £600