Fast road / race 1098 - your thoughts please.

[bmcecosse]

Yes - if you can find one !! Not many about. Still no good with 998 pistons!

[RobThomas]

I've got 3 here in Cardiff. Want one for rebuild?

[bmcecosse]

Wow - these will be worth something on ebay!
Rob - for my interest - what rods are used in these engines ? Is it the Cooper S type rod - or the standard 1098 rod ?

[RobThomas]

Halfway. EN16 (I think) with 1275 size big end journals. As strong as 1275 Midget rods but not up to "S" AEG 521 rod spec.
I've asked for £50 for a pair of bottom half engines complete, for rebuild. First come, first served. Cardiff

01446 795489

[bmcecosse]

These used to be much sought after - but now the 1275 is a better bet. If it has 'S' type rods - it must have different pistons too - with press fit gudgeon pin in the rod ?

[RobThomas]

Late 1098 Midget pistons have floating gudgeon pins and circlips. One of these blocks has a pitted piston from eating a throttle butterfly screw but the other pistons could be re-used. They are higher compression, too.

I looked at skimming some 998 pistons down for making a 1098 but gave up in the end. Not enough crown thickness.

I have a 649 cam in my 220bhp MGC. Does very little below 2500 rpm but then flies. It is, however, 500cc per cylinder and has all of the other goodies. Engine rebuild cost over £5500 back in the mid 1990s. (Whole car for sale)
Mg Metro 1275 cam might be a good choice for a 1098.

[bmcecosse]

Excellent choice for 1098. My spare engine is sitting ready to go with MG cam fitted. However - the engine in the car is performing superbly (famous last words!!) - and until it gives problems I don't have the enthusiasm to change it. In the middle of engine change on Mini at the moment - so that keeps me busy enough!

[TwincamTurbo52]

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[bmcecosse]

NO - a 1098 will snap the crank if run over 6000 for any time at all. Don't do it! The MG cam is same inlet timing to the old Cooper 997 cam (2a948) but has longer exhaust valve period and is MUCH better for it! The 'famous' SW5 cam is actually very soft timing (but it does have good lift) - it's for a road going car that needs to pass MOT emissions test. I have just swapped my fully worked 295 head for a warmed over 940 and the car goes very much better - the bigger valves make all the difference. I'm still on a 38 HIF carb (on MG inlet) and it seems to be plenty! 44 might be better - but it's been claimed by the 1360 Mini!

[RobThomas]

bmcecosse. Just wondering....

Do you not mean "the (MINOR) 1098 will snap if...."

The Later Midget 1098 crank is a very different animal and requires a different block, strap and rods.

[bmcecosse]

Yes indeed - the later heavy duty cranks can take much more punishment. But these are few and far between - although we know you have a few in stock !!

[TwincamTurbo52]

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[bmcecosse]

Amazed at the revs you are getting with the 1098 - but facts is facts. yes - lightflywheel / crank damper / all nicely balanced is all going to help - but I'm still amazed !
Interesting results you say from the SW5 - I wonder why BMC/Rover didn't just do this - basically it's just a standard cam reground to give more lift. Instead they developed the MG cam (from the 997 Cooper cam 2A948) with extra exhaust timing. And indeed - most of the performance cams tend to hav longer ex timing - and Vizard indicates too this is the way to go - even with the 'reverse' Sprint cam with 320 exhaust and just 300 inlet timing. The poor valve area thing is solved with the 940 head - it's certainly much better than the highly modified 295 I took off - direct comparison - both similar CR around 10:1.

[TwincamTurbo52]

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[TwincamTurbo52]

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[bmcecosse]

All very well (in fact truly fantastic) - but probably rather short-lived!!
Enginetuner does the beemer head conversion.
I think the very first twin cam Mini engine was done about 40 years ago with a cut-down Jaguar head bolted on a 1275S block!

[TwincamTurbo52]

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[Pandora]

Guess what.... several years down the line, 2 A-series engined racing car projects,2nd child, and a house move later and I was searching for info whilst musing over engine thoughts for my current project, and I stumbled over this thread. Took me a few minutes to realise I started it!!!!

Current project is a 1000cc clubmans car, but most of the bits I had were sold with previous projects, so at the moment I have a 948 engine needing rebuild, flat top 'slipper' type pistons and a 295 head (bare casting)

Oh, and a 1 1/2" Reece Fish carb, just for fun / period charm!

Here's a few photos of the chassis as it is at the moment - I have a way to go.......

If anyone has any suitable parts available such as cam, lightened flywheel etc for reasonable money, or has an ideal (budget) spec for a 948 based 998 engine build, do please let me know

Al

[bmcecosse]

To build a 998 - you use a 1098 block with 948 crank, and Mini 998 pistons and rods.... The 1098 block gives you cam bearings - so you can run a decent cam - I thoroughly recommend a BMC 544 cam - pretty much what they call a 286 cam these days. And - use a 940 head (not the 295) - try to find a large inlet valve version for decent money. With GOOD carbs (I suggest 2 X 1.5" SU) on long manifolds, and an lcb you should be good for almost 90 bhp, but at v high revs of course!!

[Pandora]

Does the 1098 block need decked to take Mini Pistons/ rods?

I take it the 1098 to use is the ore common small Journal Crank rather than the 2"?

Don't supose anyone near Edinburgh has a decent 1098 block going spare? or a set of Metro 998 rods and Pistons?

Al