Engines - start fresh or buy a runner?
Discussion
recently stripped the engine down for a rebuild. Now when I bought the car I was told a stack of lies about it being a 1293cc, stage 3 head and a big cam. Turns out that its just a standard bore 1275cc on a standard head thats been skimmed beyond belief and a mental 286 cam!!!!!!
So I took all the parts over to the guys at MED Engineering in Leicester to inspect it they basically said;
The heads fit for the skip.
The piston rings had that much play in them they looked like you could holahoop them round the pistons.
The crank needs a reground.
+ side is the block, gearbox and rods are good.
So my conundrum is, do I spend say 500 notes on getting a running 1275 from somewhere like fleabay and run the risk of getting another rotter or would it be best with starting fresh with what I have and get the crank ground, new rings and finding a 12G940 head? and the peice of mind I'm starting over again.
If I rebuild what I have, I can also add 1 3/4" carb, swifttune SW5 cam and high lift rockers I already have laying around.
Thoughts welcome.
Cheers.
So I took all the parts over to the guys at MED Engineering in Leicester to inspect it they basically said;
The heads fit for the skip.
The piston rings had that much play in them they looked like you could holahoop them round the pistons.
The crank needs a reground.
+ side is the block, gearbox and rods are good.
So my conundrum is, do I spend say 500 notes on getting a running 1275 from somewhere like fleabay and run the risk of getting another rotter or would it be best with starting fresh with what I have and get the crank ground, new rings and finding a 12G940 head? and the peice of mind I'm starting over again.
If I rebuild what I have, I can also add 1 3/4" carb, swifttune SW5 cam and high lift rockers I already have laying around.
Thoughts welcome.
Cheers.
i would start a fresh, how warn are the bores? if they are ok (which i suspect not if the rings are that bad) you could re ring it, i picked up a second hand crank last year for £40 which was perfect, i belive a rough price for getting one reground is circa £100.
best bet is to keep an eye out on ebay and for sale sections in mini forums and see if there are any secondhand engine bits/short engines about
what is up with the head?
best bet is to keep an eye out on ebay and for sale sections in mini forums and see if there are any secondhand engine bits/short engines about
what is up with the head?
nick1275 said:
i would start a fresh, how warn are the bores? if they are ok (which i suspect not if the rings are that bad) you could re ring it, i picked up a second hand crank last year for £40 which was perfect, i belive a rough price for getting one reground is circa £100.
best bet is to keep an eye out on ebay and for sale sections in mini forums and see if there are any secondhand engine bits/short engines about
what is up with the head?
Im not that up with my engine lingo, just going off what the guy at MED mentioned.best bet is to keep an eye out on ebay and for sale sections in mini forums and see if there are any secondhand engine bits/short engines about
what is up with the head?
The head has been skimmed to within a inch of its life, that and the ports been DIY grinded and attempt to be polished with a dremel, that coupled with the 286 cam would produce so much compression that it wouldn't come in till around 4k? and run like a bag of spanners anything under that.
He said that the bores where ok and the block looked pretty stong. Ive not looked over the piston heads much at the moment for pitting but im sure they are ok for a re-ring.
If you can re-build what you have at least you will know what you end up with, but do price it all up first. Also work out what you want Power or just a stock 1275 etc. 286 is a sports cam but if set up not to bad for the road. The 296 I ran was a bit hard for every day use but a lot of fun.
Thanks for all the advise guys. 
I have decided to re build what ive got just for peace of mind, of course the more power the better but on a small budget I guess I'll go for as much as I can get.
So what I'm thinking too start off with:
Use the standard 1275cc block, re-ring the pistons, re-grind the crank, standard 12G940 head or if I can get hold of one thats been worked on, my swiftune SW5 cam with new cam followers, SU 1 3/4" carb and some high lift rockers?
Anyone got any ideas what that would make? isn't a totally standard 1275cc around 65bhp.
I have decided to re build what ive got just for peace of mind, of course the more power the better but on a small budget I guess I'll go for as much as I can get.
So what I'm thinking too start off with:
Use the standard 1275cc block, re-ring the pistons, re-grind the crank, standard 12G940 head or if I can get hold of one thats been worked on, my swiftune SW5 cam with new cam followers, SU 1 3/4" carb and some high lift rockers?
Anyone got any ideas what that would make? isn't a totally standard 1275cc around 65bhp.
Focus Your money on the cylinder head. The SW5 is a great hotroad cam with agressive profile, big valve lift, but short duration. Peak power below 6K. Will pull from idle. Dont need the high lift rockers (can even be too hard on valve train). Ask Swiftune what valves springs they recommend. CR 9.5:1 (no more with this short cam).
Power will come from the head
. Dont need to overwork it, std MG Merto size valves are ok, with 3 angle seat cut, and some slight porting (especialy on the exhaust side). If You can afford, buy rimflows - at least exhausts.
Use the other "normal" gofaster bits like KN filter with stubstack, RC40, LCB etc.
At the end get it all set up on a good dyno.
Good luck!
Power will come from the head
. Dont need to overwork it, std MG Merto size valves are ok, with 3 angle seat cut, and some slight porting (especialy on the exhaust side). If You can afford, buy rimflows - at least exhausts.Use the other "normal" gofaster bits like KN filter with stubstack, RC40, LCB etc.
At the end get it all set up on a good dyno.
Good luck!
I am pretty sure a standard late A+ 1275 gives about 50Bhp? or did when new.
With a claimed 89n/m torque!!
As i know someone with 1!!
I hope he/we will be working on it soon to push it up a bit, +15Bhp to similar to a cooper would be good.
Also found this on tmf:
lowest bhp 1275 53 bhp fitted to mini between 1991-1996 engine no 12A2DF75/6
With a claimed 89n/m torque!!
As i know someone with 1!!
I hope he/we will be working on it soon to push it up a bit, +15Bhp to similar to a cooper would be good.
Also found this on tmf:
lowest bhp 1275 53 bhp fitted to mini between 1991-1996 engine no 12A2DF75/6
camelotr said:
Focus Your money on the cylinder head. The SW5 is a great hotroad cam with agressive profile, big valve lift, but short duration. Peak power below 6K. Will pull from idle. Dont need the high lift rockers (can even be too hard on valve train). Ask Swiftune what valves springs they recommend. CR 9.5:1 (no more with this short cam).
Power will come from the head. Dont need to overwork it, std MG Merto size valves are ok, with 3 angle seat cut, and some slight porting (especialy on the exhaust side). If You can afford, buy rimflows - at least exhausts.
Use the other "normal" gofaster bits like KN filter with stubstack, RC40, LCB etc.
At the end get it all set up on a good dyno.
Good luck!
Good info thanks for that.Power will come from the head
. Dont need to overwork it, std MG Merto size valves are ok, with 3 angle seat cut, and some slight porting (especialy on the exhaust side). If You can afford, buy rimflows - at least exhausts.Use the other "normal" gofaster bits like KN filter with stubstack, RC40, LCB etc.
At the end get it all set up on a good dyno.
Good luck!
I've sween so many second hand engines which have been bought as 'in good running order when removed' put into Minis. In many, indeed probably most cases, they have problems from the beginning and after just a short while need a full re-build.
If you want a Mini with a bit more power than standard as well, that puts more dynamic loads into the engine, so a unit in top condition is really advised.
Of course, your budget is important, but if you buy a complete engine which the seller says is in good condition (well, he would say that, wouldn't he!) for, say, £200, collect it, fit it to the gearbox with the necessary new gaskets, etc, then fit it in the car, you will be well hacked-off if it rattles, smokes or just won't at all run well.
If you are willing to learn how to build an engine yourself, with help from all of us lovely people on here, then all it will cost you will be the parts and machining costs plus a few good tools if you don't already have them. You will need a socket set and a torque wrench plus some good hand tools.
You could, for example, bore to 1330 cc (+0.060"), but a set of 21253-60 pistons, get the crank ground and the block decked, pistons fitted onto rods, clean up the head with new guides and valve seats re-faced and head face skimmed, new oil pump, new cam followers, new timing chain and water pump, new main, big-end and thrust bearings plus all gaskets for around £600. Labour is zero and, bingo, you'll have a completely new engine which will last a good while. You can pick up a bare 12G940 head casting for around £30 and you'll need a set of valves and guides. Someone on here will have a bare good head casting - I may well have one lying around if it would help.
Go on, go for it, you know it makes sense.
If you want a Mini with a bit more power than standard as well, that puts more dynamic loads into the engine, so a unit in top condition is really advised.
Of course, your budget is important, but if you buy a complete engine which the seller says is in good condition (well, he would say that, wouldn't he!) for, say, £200, collect it, fit it to the gearbox with the necessary new gaskets, etc, then fit it in the car, you will be well hacked-off if it rattles, smokes or just won't at all run well.
If you are willing to learn how to build an engine yourself, with help from all of us lovely people on here, then all it will cost you will be the parts and machining costs plus a few good tools if you don't already have them. You will need a socket set and a torque wrench plus some good hand tools.
You could, for example, bore to 1330 cc (+0.060"), but a set of 21253-60 pistons, get the crank ground and the block decked, pistons fitted onto rods, clean up the head with new guides and valve seats re-faced and head face skimmed, new oil pump, new cam followers, new timing chain and water pump, new main, big-end and thrust bearings plus all gaskets for around £600. Labour is zero and, bingo, you'll have a completely new engine which will last a good while. You can pick up a bare 12G940 head casting for around £30 and you'll need a set of valves and guides. Someone on here will have a bare good head casting - I may well have one lying around if it would help.
Go on, go for it, you know it makes sense.
The best head is the MG Metro head as it has larger inlet valves, 35.6 mm as opposed to 33.5 mm, which an advantage if you want to fit a better cam and carb.
The inlet valves can be made larger, but it normally involves having a new valve seat insert fitted for unleaded. If that is required it can be better to start with an earlier leaded head as then it is being machined for inserts for the first time without any issues.
Good luck with the build. Come back on here if you need a full build sequence or any other advice.
We are all here to help.
The inlet valves can be made larger, but it normally involves having a new valve seat insert fitted for unleaded. If that is required it can be better to start with an earlier leaded head as then it is being machined for inserts for the first time without any issues.
Good luck with the build. Come back on here if you need a full build sequence or any other advice.
We are all here to help.
Cooperman said:
If you are willing to learn how to build an engine yourself, with help from all of us lovely people on here, then all it will cost you will be the parts and machining costs plus a few good tools if you don't already have them.
Careful Peter - you could be talking yourself out of a job here! I've already got the head done for the new engine and now I'm almost finished this:
So, yes Pixel-snapper - build your own new engine (and I need to follow my own advice!
)I picked up a NOS OEM Gold seal head from fleabay, £28.00 (+10 delivary).
I took it along with two other modified 12g940 heads to Bill Richards enquiring about a porting/gas flowing service. He was less then polite about my supposedly modified heads'.... but went wild over the Gold Seal one. He had a good look with an endoscope and applied a couple of strange looking tools and declared it to be the basis of a excellent engine.
Fleabay and miniworld do throw up a few cheap ones, but most of the "ported" ones are warped... If you can get a NOS one and work forward from there it seems the best. Even a standard casting would be better in the long run.
Saving up to have you "head ported" is about as manly as it gets.......
p(n.b anyone got a link about Gold/Silver/Seal engines??? I know very little)
I took it along with two other modified 12g940 heads to Bill Richards enquiring about a porting/gas flowing service. He was less then polite about my supposedly modified heads'.... but went wild over the Gold Seal one. He had a good look with an endoscope and applied a couple of strange looking tools and declared it to be the basis of a excellent engine.
Fleabay and miniworld do throw up a few cheap ones, but most of the "ported" ones are warped... If you can get a NOS one and work forward from there it seems the best. Even a standard casting would be better in the long run.
Saving up to have you "head ported" is about as manly as it gets.......
p(n.b anyone got a link about Gold/Silver/Seal engines??? I know very little)
'Gold-Seal' engines were factory (i.e. BMC) re-conditioned engines for which you exchanged your original green painted engine. They were 'as-new' in every respect and carried the full manufacturer's warranty of 12 months or 12000 miles, whichever came first. I fitted one to an 850 I had back in 1964, before I had the confidence to do my own rebuilding.
I think, but I'm not absolutely sure, that 'Silver-seal' were also factory reconditioned but not to the same absolutely new standard.
I think, but I'm not absolutely sure, that 'Silver-seal' were also factory reconditioned but not to the same absolutely new standard.
As far as I know, Gold Seals were complete units ready to fit, and Silver seals were only short blocks delivered to garages where they fitted the old head/gearbox etc.
Although to make things more complicated, I have a gold colored "8G" early 850ccm where the head and the gearbox is green, soo must be from the old unit. Who knows?
Although to make things more complicated, I have a gold colored "8G" early 850ccm where the head and the gearbox is green, soo must be from the old unit. Who knows?
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