16 replies to this topic

[Neon]

Been to get a 998 today to rebuild over the winter. Mines done 85000 miles so i've got it in anticipation of something going wrong. My initial idea was to get it rebored as part of the rebuild, but i found out it has only done 20 - 30000 miles. If the bores are fine, is it worth oversizing it? and will i really notice the difference of a 1275 head, because i'd get it pocketed whilst being rebored.

Cheers

[fikus01]

theres no replacement for displacement!! having it overbored will give u more torque and power but with a small cc lump you are limited!!

if you are having it bored out then u mite as well have the block pocketed if u intend to fit a 940 head!

personally id stick with the smaller cc heads if u can find one tho i have heard big stories of bhp from a 998 with a 1275 head!!!

[Neon]

personally id stick with the smaller cc heads if u can find one tho i have heard big stories of bhp from a 998 with a 1275 head!!!

What do you mean by this? Stick with the 998 head, or go for the 940?

[fikus01]

i dont like the use of a 1275 head on a 998!! just feels like the ports and valves are too big, most limiting factor a 998 has is the cam!! with the smaller valves and ports you get greater airspeed and inertia so the drivability and low down torque will be better!! you may lose a small amount of power at 4500rpm and above but if u dont use that rev range u wont miss it!!

a cooper head has the 1275 port sizez and slightly bigger valves than a 998 but u wont need the block machining and u can fit it later if u want to!! once u have the block machined for the 1275 head you're stuck with it!!

[Guess-Works.com]

Only consider the rebore if the ring gap is over, if not save some money and save for a 1275...

[Neon]

I've just taken the head off and the pistons and bores look immaculate. A wee bit of carbon build up but nothing that a wire brush wont fix.
Almost seems a shame to get it rebored, so is it worth the money for the extra power i'll get?
I'm still going to strip it right down, put a new cam in and rebuild with new bearings. So ... rebore or not?

[miniboo]

depends what you want from the engine.

if you just want a replacement for your worn out one just whack itin as is and it will be fine

then maybe use your worn out one for a rebore or something like that.

if it aint broke dont fix it i say!!

[jam2005]

If you can afford it go for a 1275cc. The amount of cash you will spend on the 998cc for small amounts of extra bhp isnt worth it imo

[Neon]

Right, been having a think this afternoon and seeing as its only done 30,000miles and the bores are fine, i think i'm gonna leave it alone, decoke the head and put an uprated cam in.
Can anyone tell me what final drive this engine would have in it ~1980 (E reg i think)?

[miniboo]

do you know what car it came out of?

was it a metro or mini?

[Neon]

mini

[miniboo]

what model?

mayfair city city e etc etc

[Neon]

Haven't got a clue i'm afraid. Is there any way of telling without stripping the 'box?

[Lund]

Haven't got a clue i'm afraid. Is there any way of telling without stripping the 'box?

Do you know the registration plate (numberplate) of the Mini it came out of???

[Neon]

No sorry. Just got told its from an E reg. Basically, I want to make it 3.44 so what is involved in doing this?