9 replies to this topic

[mini-mad-mark]

Hi all,

I've been offered a 998 A+ bottom end with 500 miles only and was wondering if I could get some std 1098 pistons and add my 1098 crank and rods to make a 1098 A+ - I've been offered a 12G295 in good condition to go with it (already machined to suit 1098 compression pistons) and also offered an MG metro cam so hoping to screw together something with a bit more urge than std with a slightly lightened flywheel.

 

What does anyone think?

 

Will a (1098) A series crank fit an A+ block? - I plan to use the A+ box as well from the 998

 

 

Cheers, Mark

 

[ACDodd]

Yes it will fit. You need to regrind t he crank in the normal way if there journal are out of tolerance.

Ac

[mini-mad-mark]

Cheers - what about the overall spec/idea - do you think it will be OK as a whole with the head/cam

 

I did see that I need to use the transfer gears from the A+ set up to work with the A+ box

 

 

Regards, Mark

[ACDodd]

I would fit a more modern cam, something like, SW5, KENT 246, BP255 or my own ACD - RT cam.

Ac

[mini-mad-mark]

Cheers again - Trying to do it on a budget hence the scrounged parts list but it seemed that the 1098cc might give me a bit more torque for my "estate" ( a state !) if I could get pistons cheaply enough.

 

The 998 is very low mileage - maybe I could go for a reworked 12G202 head (from the 1098) with the flat top pistons and stick to 998cc

(The 12G295 as modified would be way too high CR with those pistons)

 

or if the budget is super tight maybe just use the 998 as is although I guess the cam won't work (well) without some sort of head change/work 

 

I'm still considering the budget at the moment  - damn those budgets 

 

Regards, Mark

[Spider]

I did a similar spec engine, on an A+ block many years ago for my girlfriend (now wife). It went really well and most people thought it was a 1275. It was a HUGE improvement overall over the 998, much more drivable all round but was considerably more thirsty.

 

 if I could get some std 1098 pistons

 

 

If buying pistons, the next +0.020" oversize will cost the same. Have the block bored to suit. It would be seriously false economy to fit standard pistons back in to a worn (even if low milage) bore, especially as it is now a 998, with a shorter stroke to part of the bore is worn and part of it that the 1098 will use is unused.

 

The chances of the bore being at an optimal size to suit the new pistons are less than my chances of winning tonight's $40M Lotto.

[carbon]

Mark,

 

If it's such a low mileage 998 then could be better (and cheaper) to upgrade this unit. The 998 can be made to give very respectable power, and the MG Metro cam would work well in either 998 or 1098.

 

Do you mean 500 miles since a rebuild, or a factory unit with only 500 miles on it?

[limby2000]

Hi Mark , i put 1098 crank and pistons in my 998 build, also had 12g295 head which i had skimmed 80 thou. The only issue i had was my big end bolt,s were fouling on my gearbox casing, although mine is auto so casing is different. Be careful that the 1098 rings will travel into bore space that was unused by the 998 piston travel, so you may need to hone that area.

[mini-mad-mark]

Great feedback!

 

The 998 was a brand new Rover short engine that a mate of mine fitted to his mini and then it had a noise (which turned out to be nothing specific but possibly idler gear noise)  so he changed to another engine - this 998 engine is virtually just run in with only 500 miles or so

 

I am considering the 998 as is, as I know it can do good things but I think the torque is what I need with the estate (its actually a project on here - the minus maxi)

 

Alternatively (if the budget allows) I might go for a re-bore on the 1100 A block (+.030 as mini spares have some cheap piston sets at that size!) and I have an electronic dizzy to suit A (not A+) and then add the 12G295 which has already been skimmed to suit th 1098 CR and also add the MG metro cam to see how that goes.

 

 

The 1275 is dead - long live the 1275!!  - I remember when I bought an Allegro 1275  engine for 25 quid and changed the diff over (3 quid for gaskets).......if only it was that easy now!

[carbon]

If it's an almost new Rover 998 short engine then I would keep it as is - don't touch the crank or pistons. But use MG Metro cam and also a well modified head that does not require the block to be pocketed.

 

If you really want a 1098 then there are plenty of well used small bore blocks around that need a rebore and rebuild, should not cost more than £100 or so for the base unit.

 

Minisport have just put NOS 998 units on their website, but these are the best part of £4K...

Edited by carbon, 24 August 2016 - 04:59 PM.