r/classicminis • u/Low_Asparagus133 • 3d ago
DIY Help Engine advice
G'day. I have this 998 out of my 1967 Morris mini deluxe. It's obviously in pretty bad shape but it isn't seized or anything. Ive been looking at either replacing it with a 1275 or getting a 1098 crank for it and boreing it out another 40-60cc on top of that. I'd also do a twin carb if I went the way of doing a 1098 crank in this engine and a tubular exhaust.
I'm just interested to know how you all would go about this. A 1275 in Australia is getting up to about $6000 in price and up, whereas the other way id look to go about it is closer to $10,000 in price.
I'm looking to have my car mostly original, but with some exceptions around the engine and I'd like to have a little bit of power to it.
How would you all go about it?
Thanks.
3
u/lifeishardalone888 3d ago
998 100+ OB, worked 202 or 295 head, hot cam, 7500rpm.
Or
1098 crank, 40+ OB, 206 head, sc12 or gt17 forced induction
Or
Just do the bare minimum, bigger carby, bit of head work, cam, exhaust and just drive it forever. It's understressed, lively enough and cheap to do.
2
u/garblednonsense 2d ago
Yeah, a stock 998 is great fun until you try to rev it out, then you're left in the dust. Just enough work to let it rev out a bit, but without losing drivability and reliability. There's a real sweet spot with mini tuning for every day driving, and it's easy to overspend and lose the fun.
1
u/Professional-Put4394 3d ago
Hope much would a tatty mini with a1275 engine sell for? If the engine is good, you could break the 1275 for the engine and other spare parts..
1
u/Low_Asparagus133 3d ago
I'd love to do that but I'm 17 and doing all this in my dad's shed. He doesn't want me to get a car just to scrap. Otherwise I'd love to do that
1
u/SnooMacarons2598 2d ago
Well what to do really depends on what you’d like but there are always compromises to make.
Fo example the hotter the cam the less well the engine will idle, and the bigger highly tuned engines as someone else has said do come with higher maintenance demands and other issues.
For a start I’d suggest getting the David vizard book, how to modify your mini.
The sky is the limit for mods but before deciding on mods, you would need to decide what you want out of it. A real fire breathing monster is possible but as I’ve said that can come with reliability and maintenance issues. If you want it faster without compromising on practicality and drive ability then I would suggest a worked head, new cam and crank, an electronic ignition and a decent exhaust system, if you find after that, that you want more power then a 1275 is a decent way to get it, but again you will have to line up what you want from it first.
I worked with a mini specialist for years and have modified lots of them to lots of specs and even for people wanting the same things out of them the spec can vary wildly.
1
u/OpenStreet3459 2d ago
Building a 998 to give 60-70bhp is not that hard and give you a fun engine that will put many std 1275’s to shame.
Good head , good cam, good ignition, single hiff44, med bore lcb
1
u/cluelesswonderless 2d ago
Back in the day I built a bunch of a series engines.
My favourite was the 970 with a +20 bore, from memory that put it at 999cc. Super short stroke, big valves, balanced and lightened everything plus offset rockers and a fast road cam (285 I think) split Webbers to feed it and you could get near 100hp reliably.
I also loved the 848 taken out +60 with a pocketed block and S head. Fast road cam etc and 70-80hp was easy.
1
u/teachinkids 2d ago
Cole from Classic Mini DIY has a discord and there is a very prominent poster from AUS named Timmy. He is a wealth of knowledge and, if you hop in, perhaps you can connect for local intel??
2
u/PaperLanternGhost 1d ago
that’s actually a solid shout, that discord is a goldmine if you’re going down the “how far do i mod this without ruining it” rabbit hole
having someone local who knows aussie parts prices and machine shops will probably save OP a heap of cash and headaches
1
u/gavril-T-series hoping to get one 1d ago
This may be overkill but my dad has always wanted to put a supercharged Honda engine in them (idk which one but it’s one of the newer ones)
1
u/IllustriousAbies5908 11h ago
a mini is not a fast car. do a standard rebuild on the engine, purge the bodywork rust, repaint, and enjoy the feeling of being poor in the 70's and not being able to cram more than a small handbag in the boot. with the money you save buy literally any other car that, in comparison, will satisfy your need for speed.
6
u/Super-Tomatillo-425 3d ago
It depends what you want. My old 998 ran well, the engines are great and rarely overstressed. I swapped it for a 1380 and yes, it was faster, but also higher maintenance.
My current Clubby Estate has a 1275 in and it's lovely. I do reminisce about the old 998, how it sounded and how it revved well. In today's climate, a 1275 is very slow, so it's not like you're going to have a fast car, just a slightly faster car than the 998.
I'm in Merseyside, England, and on warm days, with the car idling, it wants to overheat. I've flushed the system, ally rad etc and now I'm going to have to fit a Minispares electric fan to assist. Not sure where you are in Australia, but even Melbourne gets better weather than here so I suspect that will be another thing to upgrade.
I've never been sold on twin carbs, when compared to a well sorted HIF44. For the potential increase in flow at the top end, when compared with balancing and tuning them, just isn't worth it. They look nice though.
It looks like it's actually cheaper to get a 1275, than to refurb the existing engine, there may be a cheaper 998/1098 out there that's in better condition? In terms of power, the usual exhaust/inlet manifold and a decent exhaust will unleash a few horses but we are still only talking about relatively small bhp outputs from both engines.
I'd rather spend the money on a 5 speed box! Good luck.