Strange Engine Problem
Discussion
I was building a 1997 MPI engine on Saturday for a chap in our village who asked for my help.
He had a peculiar problem in that the crank was damaged and we don't know what caused it. Crank was scored, but cleaned up at -0.020" on the mains and -0.010" 0n the big ends.
Then we found that the housing for the cam centre bearing was oversize as machined from new. This we cured by using Loctite 641 to bond the new bearing in place.
On doing the final assembly of crank into block, it was very tight on the centre main when torqued up accurately. First I re-checked the end float - correct at 0.002". I checked for a bent crank, but it was fine. Then I checked the newly ground diameters - all absolutely spot-on. Then I swapped the bearing shells around, but it was still tight on the centre main, so the bearing shells were all OK.
We cured the problem by lightly linishing the steel backing on the bearing shells until the crank spun nicely with our fingers. It seems the centre main was too small from new, and I now suspect that the initial cause of the crank/bearing damage was just this, although i can't imagine Rover assembly-line workers caring too much. So the block had been factory machined with an oversize cam bearing housing and an undersize main bearing housing - bloody wonderful!
With hindsight I should, maybe, have just used a light hone on the centre main bearing housing and cap, but I think it was safer to linish the bearing shells.
Has anyone else ever had this happen, as in 40+ years of building 'A-Series' engines it's never happened to me before?
He had a peculiar problem in that the crank was damaged and we don't know what caused it. Crank was scored, but cleaned up at -0.020" on the mains and -0.010" 0n the big ends.
Then we found that the housing for the cam centre bearing was oversize as machined from new. This we cured by using Loctite 641 to bond the new bearing in place.
On doing the final assembly of crank into block, it was very tight on the centre main when torqued up accurately. First I re-checked the end float - correct at 0.002". I checked for a bent crank, but it was fine. Then I checked the newly ground diameters - all absolutely spot-on. Then I swapped the bearing shells around, but it was still tight on the centre main, so the bearing shells were all OK.
We cured the problem by lightly linishing the steel backing on the bearing shells until the crank spun nicely with our fingers. It seems the centre main was too small from new, and I now suspect that the initial cause of the crank/bearing damage was just this, although i can't imagine Rover assembly-line workers caring too much. So the block had been factory machined with an oversize cam bearing housing and an undersize main bearing housing - bloody wonderful!
With hindsight I should, maybe, have just used a light hone on the centre main bearing housing and cap, but I think it was safer to linish the bearing shells.
Has anyone else ever had this happen, as in 40+ years of building 'A-Series' engines it's never happened to me before?
You can get a tight crank if the thrust beaings are not set correctly. I've had standard thrusts come up tight due, I think, to crank tolerances. All you do then is to linish the backface of one pair of thrusts until you get 0.002" float.
I once was asked to rebuild a 1275 engine with excess end-float. the guy said he and his friend had only re-built it a few months previously, but the crank had 0.015" float. They had put the thrust bearings in the wrong way round. i.e. with the steel backing against the crank faces. Result: one damaged crank and a need to machine down +0.030" oversize thrusts after re-grinding the thrust faces of the crank. That's fine, except that you can no longer get thrusts at 0.030", the biggest oversize now available is +0.003". Still, everyone has to learn and they won't be doing that again.
However, that crank problem I started off this thread with is very strange, as is the oversize cam bearing housing. Rover crap quality control, or am I being unkind?
I once was asked to rebuild a 1275 engine with excess end-float. the guy said he and his friend had only re-built it a few months previously, but the crank had 0.015" float. They had put the thrust bearings in the wrong way round. i.e. with the steel backing against the crank faces. Result: one damaged crank and a need to machine down +0.030" oversize thrusts after re-grinding the thrust faces of the crank. That's fine, except that you can no longer get thrusts at 0.030", the biggest oversize now available is +0.003". Still, everyone has to learn and they won't be doing that again.
However, that crank problem I started off this thread with is very strange, as is the oversize cam bearing housing. Rover crap quality control, or am I being unkind?
Cooperman said:
However, that crank problem I started off this thread with is very strange, as is the oversize cam bearing housing. Rover crap quality control, or am I being unkind?
Not unkind at all - I think implying that Rover had any sort of quality control whatsoever is probably being very generous
Accuracy of manufacture was never a BMC-British Leyland-Austin-Morris-Rover strong point, was it.
I am building a 1098 engine for an Historic Rally Sprite (Frog Eye) and I have an original crank. The difference in crank throw is 0.006" between 1 and 3, and that's within the tolerances for 1963-ish. Of course, for a full race engine I would normally get a specialist machine shop to 'stroke & index' the crank to remove all errors to within 0.0005" (half a thou), but that's really not cheap and can cost £300 to get it absolutely correct. It's been done on my 1964 historic rally car, but unless you are going to be using over 7000 rpm it's probably not worth the added cost. Is does make a smoother engine, but probably not much power gain, so worthwhile only on full competition engines.
These tolerances are a factor which has to be considered in all 'A-Series' builds if one is to get a good engine.
One thing I am always amazed at is the poor quality of some engine builds I see and the prices charged. I'm thinking of semi-retiring and spending 3 days a week on 'A-Series' and Ford 'Kent' engine rebuilds to a high standard. The question is, is there enough of this type of work to keep me busy?
I am building a 1098 engine for an Historic Rally Sprite (Frog Eye) and I have an original crank. The difference in crank throw is 0.006" between 1 and 3, and that's within the tolerances for 1963-ish. Of course, for a full race engine I would normally get a specialist machine shop to 'stroke & index' the crank to remove all errors to within 0.0005" (half a thou), but that's really not cheap and can cost £300 to get it absolutely correct. It's been done on my 1964 historic rally car, but unless you are going to be using over 7000 rpm it's probably not worth the added cost. Is does make a smoother engine, but probably not much power gain, so worthwhile only on full competition engines.
These tolerances are a factor which has to be considered in all 'A-Series' builds if one is to get a good engine.
One thing I am always amazed at is the poor quality of some engine builds I see and the prices charged. I'm thinking of semi-retiring and spending 3 days a week on 'A-Series' and Ford 'Kent' engine rebuilds to a high standard. The question is, is there enough of this type of work to keep me busy?
Cooperman said:
I'm thinking of semi-retiring and spending 3 days a week on 'A-Series' and Ford 'Kent' engine rebuilds to a high standard. The question is, is there enough of this type of work to keep me busy?
Sounds like a Good Plan, especially if you are able to be flexible with your 'day job' hours and take up any slack times in the engine work.
Out of Interest, how many hours would you expect to spend on an engine assembly?
name said:
The question is, is there enough of this type of work to keep me busy?
Ah - the $64k question !
The problem as I see it is that everyone wants the best they can get, and complains about poor workmanship etc.
BUT
no-one wants to pay more than the lowest quote they can get, regardless of quality or service.
Seeing as how it's 'semi-retirement' why not just try it and see how it goes?
Your track record, if I may call it that, should be a good selling point. Why don't you send out some flyers to gauge the interest?
I would like to say yes, but I fear the answer is no.
A couple of very good friends of mine prepped and raced minis in the British Touring Car Championship way back when. They were considered the top engine builder of the time with others like Jon Mowatt and Glyn Swift.
They are still going looking after historic touring cars and they build the occasional Mini engine. One thing they say is if the first question you ask is ‘How much will it cost?’ they wont even bother. They only use the best components, spending time to insure the whole engine is perfect. Which normally results in a bill twice or three times what you would find from Minispares, but the results speak for themselves.
IMHO it would seem people want a ‘cheap bang’ pay the bare minimum to get the most value BHP/£, which of course there is nothing wrong with. I just conceder going that little further, just to get that little extra.
A couple of very good friends of mine prepped and raced minis in the British Touring Car Championship way back when. They were considered the top engine builder of the time with others like Jon Mowatt and Glyn Swift.
They are still going looking after historic touring cars and they build the occasional Mini engine. One thing they say is if the first question you ask is ‘How much will it cost?’ they wont even bother. They only use the best components, spending time to insure the whole engine is perfect. Which normally results in a bill twice or three times what you would find from Minispares, but the results speak for themselves.
IMHO it would seem people want a ‘cheap bang’ pay the bare minimum to get the most value BHP/£, which of course there is nothing wrong with. I just conceder going that little further, just to get that little extra.
name said:
....going that little further, just to get that little extra
This is the nub of it isn't it.
You'll never compete on price with the big players like Minispares et al.
You have to offer a higher quality product - but will the market see it as a sufficiently better product, to sustain the higher cost?
Unfortunatly I suspect it's a very small niche market and I doubt it would be commercially viable - but as a part time, paying 'hobby' it could work.
Agree with above, to a great extent, folks read a bhp figure on a leaflet, believe it, see how cheap the product is then spend their cash.
In all honesty how many drivers can feel the difference between 1 or 2 bhp. It's the flexibility and useability that you can feel and a dyno doesn't really show you that, at least not in the pub where the bhp figures come out. (Is that bar torque?)
On the othr hand however, when I built my Caterham in 1990, I looked around for a built up engine to keep th car registered as a new car. There ws all sort of quotes from the likes of Aldon, Chamberlain, Vulcan I think, Holbay andloads of others, all with fancy prices. Spoke to Scholar who were building Formula Ford engines at that time. Their answer was "what do you need a verier timing system for once we have set up the engine, what do you need a high press oil pump for etc etc. Their price was remarkably good considering their reputation andboy did that engine work. Fast reliable pulled from most revs etcetc.
So sometimes a cheaper build is worth it.
That dosn't really help Peter, does it?
Sorry about any typos, sore finger from an accident with a saw and a bit of wood!
In all honesty how many drivers can feel the difference between 1 or 2 bhp. It's the flexibility and useability that you can feel and a dyno doesn't really show you that, at least not in the pub where the bhp figures come out. (Is that bar torque?)
On the othr hand however, when I built my Caterham in 1990, I looked around for a built up engine to keep th car registered as a new car. There ws all sort of quotes from the likes of Aldon, Chamberlain, Vulcan I think, Holbay andloads of others, all with fancy prices. Spoke to Scholar who were building Formula Ford engines at that time. Their answer was "what do you need a verier timing system for once we have set up the engine, what do you need a high press oil pump for etc etc. Their price was remarkably good considering their reputation andboy did that engine work. Fast reliable pulled from most revs etcetc.
So sometimes a cheaper build is worth it.
That dosn't really help Peter, does it?
Sorry about any typos, sore finger from an accident with a saw and a bit of wood!
Thanks for that chaps.
It would really only be a hobby-job for retirement so I would only need to charge about £25 per hour. To build a Mini engine properly takes, on average, between 30 and 40 hours, including setting it up on the gearbox and re-building the head. Gas flowing the head takes it towards the 40 hour figure. Thus 1 or 2 engines a month would be fine.
I'm with you all on only using the best and always new parts, although some builders do go 'over the top' on the parts, on which they probably make a biggish mark-up.
Yes, vernier timing gears are unnecessary if you time-in with offset woodruff keys. That always saves a bit.
I was once asked 'how cheaply could you build a Cooper engine'. My answer was, "I can't, it's either built properly or not at all".
It would really only be a hobby-job for retirement so I would only need to charge about £25 per hour. To build a Mini engine properly takes, on average, between 30 and 40 hours, including setting it up on the gearbox and re-building the head. Gas flowing the head takes it towards the 40 hour figure. Thus 1 or 2 engines a month would be fine.
I'm with you all on only using the best and always new parts, although some builders do go 'over the top' on the parts, on which they probably make a biggish mark-up.
Yes, vernier timing gears are unnecessary if you time-in with offset woodruff keys. That always saves a bit.
I was once asked 'how cheaply could you build a Cooper engine'. My answer was, "I can't, it's either built properly or not at all".
Cooperman said:
It would really only be a hobby-job for retirement so I would only need to charge about £25 per hour.
I didn't get that when I was working for a national consultancy (although they charged me out at more than that)!
I certainly don't get that in my new role as village postie.
I don't charge anywhere near that in my new hobby job doing planning applications either (although my wife says I should charge more).
Goog luck though Peter, I'm sure your reputation will carry you through, you have already had a number of satisfied customers. Wish I could get as much satisfactionout of my jobs.
Tony H
skyedriver said:
It would really only be a hobby-job for retirement so I would only need to charge about £25 per hour.
I didn't get that when I was working for a national consultancy (although they charged me out at more than that)!
I certainly don't get that in my new role as village postie.
I don't charge anywhere near that in my new hobby job doing planning applications either (although my wife says I should charge more).
Goog luck though Peter, I'm sure your reputation will carry you through, you have already had a number of satisfied customers. Wish I could get as much satisfactionout of my jobs.
Tony H
only £25 an hour will surely see your business levels rocket, i'm looking for a nice engine at the moment and some of the quotes i've had for the spec I would like have literally taken my breath away!
4k and up...starting with people i've never heard of and going up to crazyness for the likes of swiftune (who incidentally aren't doing any private builds for a while, only race cars) so it sounds like for parts of £1600 and labour amounting to £1000 plus £500 to cover anything unseen eventualities you would get my business for sure!
Thanks for all the encouragement.
I'll post as to what I decide to do, if that's OK.
I wonder what is so special that these really expensive boys charge. True, they may have sophisticated flow benches, dynos, etc, but for a good fast road or rally engine the technology to get decent power is quite well established, the skill is in the application of the technology and the care in the build standard. My own Cooper 'S' gives about 115 flywheel bhp at 6200 on the rollers and it's self built. The only really extravagant thing is the 'stroked & indexed' crank and the balancing, both of which don't increase the power, just make it more smnooth, er, maybe. Those two items probably add about £600 to the bought out services, not the labour charge for the building.
I'll post as to what I decide to do, if that's OK.
I wonder what is so special that these really expensive boys charge. True, they may have sophisticated flow benches, dynos, etc, but for a good fast road or rally engine the technology to get decent power is quite well established, the skill is in the application of the technology and the care in the build standard. My own Cooper 'S' gives about 115 flywheel bhp at 6200 on the rollers and it's self built. The only really extravagant thing is the 'stroked & indexed' crank and the balancing, both of which don't increase the power, just make it more smnooth, er, maybe. Those two items probably add about £600 to the bought out services, not the labour charge for the building.
Cooperman said:
I wonder what is so special that these really expensive boys charge. True, they may have sophisticated flow benches, dynos, etc, but for a good fast road or rally engine the technology to get decent power is quite well established, the skill is in the application of the technology and the care in the build standard. .
Too true Peter, fancy machinery is useless without the technical knowhow. You can get a hell of a long way with technical and mechanical "feel"
Best of luck
ps have just up ed my charges for the next Planning Application
I have heard of this problem being caused by fitting bearing caps from a different engine, which obviously were not line bored to suit that engine, and cause the bearings to bind.
I have also heard of blocks that weren't line bored very accurately in the first place (worn tooling perhaps).
I have also heard of blocks that weren't line bored very accurately in the first place (worn tooling perhaps).
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