Respect to you for being an imp doctor and keeping them alive! You make it look super easy Andy. I have two engines in the garage. An 875cc and a 998cc. The 875cc doesnt look in the best shape as was left to the elements. Ill be joining your waiting list soon as would like to get the 1967 Davrian imp sorted (which hasnt seen the roads for 30 years lol). Excellent video as usual 10/10
Thanks for the kind words, i am very lucky to have a job i enjoy and be able to share my exploits so easily through youtube ! Davrian imp sounds awesome, we need them all out racing👍
A high speed misfire may or may not be traced to a wide spark gap on the spark plug. I did some work to study this. As the engine speed increases there is less time for the ignition system to build up the charge for the spark. If the gap is too wide and there is not enough charge, no spark. Too narrow is equally bad if not worse. The electrode gap itself should be flat and absolutely parallel. The actual gap may depend on the time constant of the ignition system, and the compression ratio pushing molecules closer together (the 10kV per cm is only true for dry air at 1 atm). Assuming you have electronic ignition it is usually 0.70mm (note that second zero, it means to within 0.005mm).
We found that so many coils wouldn’t give consistent sparks at high comp and revs… in the end we switched to USA-made flamethrower coils, which having been built for V8 motors running to 6000rpm could ‘keep up’ with our 911 6-cyl engines at 7500…. Also, getting decent points which didn’t float at high revs was a constant challenge: new-old-stock Bosch points were the dream fix. Great to see so much thought going into developing these great engines….. good work.
My uncle had an Imp and I always looked forward to going for a drive in it, man it really was a little pocket rocket, still get a tear in my eye when I think about it
Another excellent video Andy. Finally got around to fitting my ‘Will Parry’ manifold. Engine now much more willing. Just needs a rolling road session to optimise the fuel and ignition maps.
I REALLY had some important things to do, yet - even though an 'A' series / Dave Vizard fan whose done detailed engine mods of my own, I found this detailed explanation of this engine captivating. You really describe technical issues well.
WOW! That was interesting. Never realised the Imp motor was still being raced anywhere. I'm glad you mentioned the theoretical and dynamic compression (even if just in passing) For the last 30 yrs or more I've been telling people theoretical (static) CR is actually pretty meaningless as cam events give completely different numbers. I 99% did motorcycle engines and as long as cranking compression wasn't over 215psi I knew they would be okay. I remember reading an article in the early 70's when Hillman Imp engines were being used for sidecar racing (before 600cc limit was introduced). There was a mention they were also being used in some powerboat class (South Africa or Australia) making around 130bhp due to being run much cooler on lake/river water (didn't go over 80 deg C as they were not a sealed system) 115 bhp today is pretty phenomenal for what is basically a very simple motor designed for easy of build not performance
First video I've watch of yours Andy, impressed with your no-nonsense, organised and clear talk through with no waffle. I've never had an Imp, but they do intrigue me. My dear granny had one in the late 70's, early 80's.... doubt it's still around, given how bad she was a driving, if you opened that engine & box up, it'd be 99% filings 😂
Thanks, yes you would be surprised how resilient to abuse the units are ! type the reg no on the hillman imp facebook page, if it still exists someone on there will know about it !
@@thehillmanator My pleasure! ...well if the Imps internals could cope with her 'if you can't find it, grind it' approach then I'm sure NASA probably acquired Hillman's engineering technology! I have a feeling hers was gold/brown, but the problem is, the car was always on a private plate, so unless someone has the full history, it might be hard to find. No way I could find the original reg plate now. Interestingly, my grandfather sold the car to a dealer, forgetting to remove the plate and by the time he'd got back to the dealer, he'd sold it and the family plate (one of a series of 3) was never seen again. That is, until I was watching Harry reviewing the Silverstone auctions in 2021, he stumbled across a black Porsche GT3 and I literally fell off my chair because there the plate was! 15:43 into this vid... czcams.com/video/FZktOWcVeeA/video.html Now I can't seem to erase the idea of my granny drifting a bad boy GT3 around the lanes!!
My first car at 16 then on the road at 17, cooked it after about three years. Singer Chamois in deep blue with the white stripe down the side. 85mph on a downhill run with the doors rattling in the frames. I enjoyed your content and have subscribed, cheers.
Similar here except a Hillman Imp Californian (same shape as the Chamois but just 2 headlamps, single carb etc.) It was a bit of a heap, but I had a lot of fun with it and learnt a bit about car maintenance through it.
Interesting,I used to race a 850 Imp in the early 70’s, I would change my carrier and followers every three races or the followers would have a tendency to tip and break due to so much of the carrier being machined away for cam clearance. A great car,I did have the 850 lap record at Aintree in 72.
I remember building Imp engines with 12.5:1 compression ratio 50years ago, without problems, so these days I can't imagine 14.1:1 would give much trouble.
Another great vid mate. Just watched this one with Maisie, she was absolutely fascinated! She says all the things I've been telling her make more sense now - I should have shown her JonesieTV sooner!!
@@thehillmanator What? No pintos? I hope there will be at least some proper engines? I'll put it to her when the time comes, but she may want something more advanced than working on water pump engines all the time...
Little gem from Coventry Climax. It's a shame that the development of the car itself was rushed, but the engine was a peach compared to the competition at the time. Obviously, a 5 bearing crank would have been better.
Higher compression engines are more efficient, you have to be careful with ignition and cam timing; more can lap will add exhaust gas recirculation to cool combustion and make it work.
Had a bit of fun with imps back in the day. My mates dad welded up a tubed alloy frame with two seats and big wide wheels. We had to put tractor weights on the front to steer. It was scary to drive at speed.. It left a mk1 eascort rs2000 for dead. I cant mind if it was 4 Honda or Kawasaki carbs but you could wheelie in first and second. It got cut up after a horrific accident.
Last of the Coventry Climax line , a tiny screaming all ally lump that started life a driving a Godiva fire pump, as in the 1930,s Coventry Climax cut their teeth souping up side valve Austin 7 engines for affordable entry level competition racing, some fitted with a blower burning 87 octane aviation petrol.
That's a very clean-sounding run on the dyno there. Also, I know economy isn't the prime concern in this application, but the 14:1 compression ratio should make it very economical to drive on the road.
It is. It's been standard for a couple of years - if you drive a Mazda or a Toyota. Mazda's SkyActiv 2.0 and 2.5 liter engines user 14.1:1 compression ratio. Toyota also uses those engines in hybrid cars (Corolla, Prius, Rav4, Camry...) Mazda went a bit further with SkyActive X gas engine that uses 16.3:1 compression ratio (and it doesn't need sparkplugs to operate at certain circumstances). Currently, only Mazda and Toyota use engines with this extreme ratios in production cars.
yes thermal efficiency is something i need to learn more about, modern cars running high compression ratios have a massive advantage as they tend to be direct chamber fuel injection, so i guess if you can control the point of injection you have good control over when the burn starts!
@@Jamesibbotson875 Haha! I know What you mean. When I'd spent about £1000 on the 1275 engine of my Allegro estate, back when £1000 was a lot of money, I got through a pair of front tyres in only about two weeks. It was such fun.
Can you run it on E85? Well, if its says pumpfuel in the rulebook and you can buy it from a pump.. E85 stands up to more compression and ignition as its higher octane, but lower on energy so needs about 30% more of it. Just an idea. Nothing to be upset about (for eldery people! As they tend to hate it..?)
Had an Imp 875 in rhe 70's after my Mini 850. A much better car in my opinion. They had a reputation for overheating and being hard to work on. Not so for mine. I reshimmed the cam, changed the clutch plate and thrust bearing, serviced it and even changed the baulk rings in the transaxle. Engine easy to get out and get apart. Mini was a lumpy bumpy rattly rustbox!
23:18 Does the car have a mapped ignition or is it using mechanical advance? The distributor appears to have a magnetic pickup seen at 18:00. Some classic car racing rules say you must keep the original points and/or mechanical advance system, so no ECU permitted. What are the rules for ignition systems in this classic/historic racing class?
I had this problem regulation in the French Maxi-Mille series in 2002. The race 1040 had electronic ignition and we had to change it en route to Nogaro with the car on the trailer! I'd never seen this circuit and the car had stock road gearbox, and was totally untested, but still times 7th out of 32 starters....it showed great promise, but had to be retired in the race due to the damned scroll joint letting oil mist get to the left rear tyre....
@@thehillmanator thanks for reply and that makes sense to me. Let people get rid of the sometimes unreliable points and condenser where spare parts might be in short supply for some older cars. But I don't think ECUs and digital mapped timing belong in classic/historic classes.
It's over 100bhp per litre, which used to be considered good for an atmo engine on CB ignition....and with only one cam! I have an 1800 Rover block here which gave 213bhp on Emerald's dyno but they reckoned it'd have gone to 225 if I hadn't forgotten to put the right fuel pump on it. The pump was for 120bhp...... Things have moved on....and having another cam and fuel injection is part of it.
They ran more hp back in the day, we stick to 8500rpm to try and keep the parts inside the engine 🤣 i have been told numerous times by ex racer 10 k was normal!!
? Where are the proper block main bearing supports would not trust that above 8Krmp at all I would have expected more than that out of a 1040 our old 998 made 125 but then it had all the bottom end done .
The nut and stud type block strengthening kit seems to work very well, all Ian Carters engines were done this way. The blocks do look more substantial i have to agree👍
@@thehillmanator Wow! 1040CC with dual twin barrel 45mm carbs. That's amazing. I'm running twin dual barrel 'baby' Dellorto 32mm DHLBs with 28mm chokes on my bored and stroked (73mm x 82mm) 1375CC Honda Civic EB3 street engine in my 78 Civic.
@@betacam235 Andy is running 45s on the engine above. The Webers and the Dells are essentially the same carbs. The Dells came out 10 years later and have a few improvements, like easier access to the jets. Must be a pretty narrow power band running those bigger carbs.
@@RestorationWatch I like the dellOrtos. Had a pair on a Ford Twincam in an old Caterham, and I now have 40 on an MG Metro 1275 in a 63 year old Berkeley T60 3 wheeler which should be fun assuming I manage to get it on French plates....difficult as some crim in UK stole its ID (chassis number and reg number) put it on one of the 2,000,000 'stolen' V5cs and kindly registered it in France in 2011, so mine (on GENUINE docs) was refused as "It's already registered here". I'll get there in the end, it's only 2 years so far..... I agree the dellOrto is an improved Weber DCOE.
But this 14.1:1 compression ratio is supposed to be way to much. A lot of pinking and similar unfriendly things. How come this is working out. Or is the 14.1 : 1 ratio a miscalculation?? Or will this compression ratio a new step of Imp competition engine??
hi no miscalculation, definitely pushing the fuel to the limit, engine ran very little ignition advance and also rich to keep things cool, wouldn’t do another that high, very little gains.
Respect to you for being an imp doctor and keeping them alive!
You make it look super easy Andy.
I have two engines in the garage. An 875cc and a 998cc. The 875cc doesnt look in the best shape as was left to the elements. Ill be joining your waiting list soon as would like to get the 1967 Davrian imp sorted (which hasnt seen the roads for 30 years lol).
Excellent video as usual 10/10
Thanks for the kind words, i am very lucky to have a job i enjoy and be able to share my exploits so easily through youtube !
Davrian imp sounds awesome, we need them all out racing👍
A high speed misfire may or may not be traced to a wide spark gap on the spark plug. I did some work to study this. As the engine speed increases there is less time for the ignition system to build up the charge for the spark. If the gap is too wide and there is not enough charge, no spark. Too narrow is equally bad if not worse. The electrode gap itself should be flat and absolutely parallel. The actual gap may depend on the time constant of the ignition system, and the compression ratio pushing molecules closer together (the 10kV per cm is only true for dry air at 1 atm). Assuming you have electronic ignition it is usually 0.70mm (note that second zero, it means to within 0.005mm).
We found that so many coils wouldn’t give consistent sparks at high comp and revs… in the end we switched to USA-made flamethrower coils, which having been built for V8 motors running to 6000rpm could ‘keep up’ with our 911 6-cyl engines at 7500…. Also, getting decent points which didn’t float at high revs was a constant challenge: new-old-stock Bosch points were the dream fix. Great to see so much thought going into developing these great engines….. good work.
You two make a good team! Thanks for the update its a very interesting engine
Thanks for putting this out there.. very informative and super cool
My uncle had an Imp and I always looked forward to going for a drive in it, man it really was a little pocket rocket, still get a tear in my eye when I think about it
Another excellent video Andy. Finally got around to fitting my ‘Will Parry’ manifold. Engine now much more willing. Just needs a rolling road session to optimise the fuel and ignition maps.
I REALLY had some important things to do, yet - even though an 'A' series / Dave Vizard fan whose done detailed engine mods of my own, I found this detailed explanation of this engine captivating. You really describe technical issues well.
Thank you, lots more to come 👍
Thanks Andy enjoyed that. Nice job.
Lovely video, Andy. Nice to see the gret work you do and how clean you keep the place! 🤣
Thank you, ha ha it’s a touch cluttered!
Interesting and informative as always.
amazing torque from an imp engine Andy, nice work
Outstanding Job Andy, Dyno cell as tidy as Bob`s.. Great Vid well done. Rodders
thanks rodders, hope you are all well? yes dyno is moderately tidier thank bobs you can actually park your brew cup !!!
WOW!
That was interesting.
Never realised the Imp motor was still being raced anywhere.
I'm glad you mentioned the theoretical and dynamic compression (even if just in passing)
For the last 30 yrs or more I've been telling people theoretical (static) CR is actually pretty meaningless as cam events give completely different numbers.
I 99% did motorcycle engines and as long as cranking compression wasn't over 215psi I knew they would be okay.
I remember reading an article in the early 70's when Hillman Imp engines were being used for sidecar racing (before 600cc limit was introduced).
There was a mention they were also being used in some powerboat class (South Africa or Australia) making around 130bhp due to being run much cooler on lake/river water (didn't go over 80 deg C as they were not a sealed system)
115 bhp today is pretty phenomenal for what is basically a very simple motor designed for easy of build not performance
It was designed to run the firepump at max revs all day so a great basis for a lightweight race engine. Mike Parkes seemed keen on it....
Thank you, yes that’s how i work out roughly where i am advance wise, everything works back from a cylinder pressure on cranking !!
First video I've watch of yours Andy, impressed with your no-nonsense, organised and clear talk through with no waffle. I've never had an Imp, but they do intrigue me. My dear granny had one in the late 70's, early 80's.... doubt it's still around, given how bad she was a driving, if you opened that engine & box up, it'd be 99% filings 😂
Thanks, yes you would be surprised how resilient to abuse the units are ! type the reg no on the hillman imp facebook page, if it still exists someone on there will know about it !
@@thehillmanator My pleasure! ...well if the Imps internals could cope with her 'if you can't find it, grind it' approach then I'm sure NASA probably acquired Hillman's engineering technology!
I have a feeling hers was gold/brown, but the problem is, the car was always on a private plate, so unless someone has the full history, it might be hard to find. No way I could find the original reg plate now.
Interestingly, my grandfather sold the car to a dealer, forgetting to remove the plate and by the time he'd got back to the dealer, he'd sold it and the family plate (one of a series of 3) was never seen again. That is, until I was watching Harry reviewing the Silverstone auctions in 2021, he stumbled across a black Porsche GT3 and I literally fell off my chair because there the plate was!
15:43 into this vid...
czcams.com/video/FZktOWcVeeA/video.html
Now I can't seem to erase the idea of my granny drifting a bad boy GT3 around the lanes!!
My first car at 16 then on the road at 17, cooked it after about three years. Singer Chamois in deep blue with the white stripe down the side. 85mph on a downhill run with the doors rattling in the frames. I enjoyed your content and have subscribed, cheers.
Similar here except a Hillman Imp Californian (same shape as the Chamois but just 2 headlamps, single carb etc.) It was a bit of a heap, but I had a lot of fun with it and learnt a bit about car maintenance through it.
mine too, i had painted a red stripe on a white imp delux, starsky and hutch style ! loved that car so much ❤️
This was interesting. tHanks for the video!
thanks, more to come 👍
Interesting,I used to race a 850 Imp in the early 70’s, I would change my carrier and followers every three races or the followers would have a tendency to tip and break due to so much of the carrier being machined away for cam clearance. A great car,I did have the 850 lap record at Aintree in 72.
Brass sleeve the carrier
I remember building Imp engines with 12.5:1 compression ratio 50years ago, without problems, so these days I can't imagine 14.1:1 would give much trouble.
new sub...great content
Another great vid mate. Just watched this one with Maisie, she was absolutely fascinated! She says all the things I've been telling her make more sense now - I should have shown her JonesieTV sooner!!
thanks pal, she can have a job when old enough, but we won’t be having any pinto lumps in again 🤣🤣
@@thehillmanator What? No pintos? I hope there will be at least some proper engines? I'll put it to her when the time comes, but she may want something more advanced than working on water pump engines all the time...
Little gem from Coventry Climax. It's a shame that the development of the car itself was rushed, but the engine was a peach compared to the competition at the time. Obviously, a 5 bearing crank would have been better.
I have a five bearing imp engine apparently cast by the rootes competition department mid 1960’s, i will do a video at some point on it 👍
@@thehillmanator Wow!
@@thehillmanator I spoke with an older Imp tuner back in 2002 who had one, and knew a lot about them...Denis something...I've lost his details.
That dyno room is fascinating in itself.
🤣🤣 think i might do a basic explanation on as to how the dyno works 👍
@@thehillmanator Looking forward to it....(take your time). It will be fun watching. I always wonder how they calibrate those things.
"Imp diesel" 😂
Even I noticed those cracks in the stiffener plate before you mentioned them - never appreciated it's the resonance that causes it.
hope your well steven, regards to Pat, maybe see you at gold cup ?
Very informative again Andy, do you take AMEX?? :D
Seen a few of those imp engines melted with just the crank and rods lying in the engine bay 🙈 never owned an imp, pretty car and engine 👍🏻😎
Higher compression engines are more efficient, you have to be careful with ignition and cam timing; more can lap will add exhaust gas recirculation to cool combustion and make it work.
Thanks for the tips!
Had a bit of fun with imps back in the day. My mates dad welded up a tubed alloy frame with two seats and big wide wheels. We had to put tractor weights on the front to steer. It was scary to drive at speed.. It left a mk1 eascort rs2000 for dead. I cant mind if it was 4 Honda or Kawasaki carbs but you could wheelie in first and second. It got cut up after a horrific accident.
wow yea sounds like fun, shame these types of buggies don’t get made any more.
Last of the Coventry Climax line , a tiny screaming all ally lump that started life a driving a Godiva fire pump, as in the 1930,s Coventry Climax cut their teeth souping up side valve Austin 7 engines for affordable entry level competition racing, some fitted with a blower burning 87 octane aviation petrol.
That's a very clean-sounding run on the dyno there. Also, I know economy isn't the prime concern in this application, but the 14:1 compression ratio should make it very economical to drive on the road.
It is. It's been standard for a couple of years - if you drive a Mazda or a Toyota. Mazda's SkyActiv 2.0 and 2.5 liter engines user 14.1:1 compression ratio. Toyota also uses those engines in hybrid cars (Corolla, Prius, Rav4, Camry...) Mazda went a bit further with SkyActive X gas engine that uses 16.3:1 compression ratio (and it doesn't need sparkplugs to operate at certain circumstances).
Currently, only Mazda and Toyota use engines with this extreme ratios in production cars.
@@kitko33 Thanks for that extra info
yes thermal efficiency is something i need to learn more about, modern cars running high compression ratios have a massive advantage as they tend to be direct chamber fuel injection, so i guess if you can control the point of injection you have good control over when the burn starts!
I can promise it’s not great on fuel on the road! Might be my right foot causing that!😬😂
@@Jamesibbotson875 Haha! I know What you mean. When I'd spent about £1000 on the 1275 engine of my Allegro estate, back when £1000 was a lot of money, I got through a pair of front tyres in only about two weeks. It was such fun.
Can you run it on E85? Well, if its says pumpfuel in the rulebook and you can buy it from a pump.. E85 stands up to more compression and ignition as its higher octane, but lower on energy so needs about 30% more of it. Just an idea. Nothing to be upset about (for eldery people! As they tend to hate it..?)
It would be interesting to do a back to back run, see exactly how the power would be effected.
Had an Imp 875 in rhe 70's after my Mini 850. A much better car in my opinion. They had a reputation for overheating and being hard to work on. Not so for mine. I reshimmed the cam, changed the clutch plate and thrust bearing, serviced it and even changed the baulk rings in the transaxle. Engine easy to get out and get apart. Mini was a lumpy bumpy rattly rustbox!
hillman imps attract hands on engineers !!
23:18 Does the car have a mapped ignition or is it using mechanical advance? The distributor appears to have a magnetic pickup seen at 18:00. Some classic car racing rules say you must keep the original points and/or mechanical advance system, so no ECU permitted. What are the rules for ignition systems in this classic/historic racing class?
Advance has to be mechanical, electronics are purely for triggering the spark reliably.
I had this problem regulation in the French Maxi-Mille series in 2002. The race 1040 had electronic ignition and we had to change it en route to Nogaro with the car on the trailer!
I'd never seen this circuit and the car had stock road gearbox, and was totally untested, but still times 7th out of 32 starters....it showed great promise, but had to be retired in the race due to the damned scroll joint letting oil mist get to the left rear tyre....
@@thehillmanator thanks for reply and that makes sense to me. Let people get rid of the sometimes unreliable points and condenser where spare parts might be in short supply for some older cars. But I don't think ECUs and digital mapped timing belong in classic/historic classes.
110 bhp out of that size engine is brilliant.
It's over 100bhp per litre, which used to be considered good for an atmo engine on CB ignition....and with only one cam!
I have an 1800 Rover block here which gave 213bhp on Emerald's dyno but they reckoned it'd have gone to 225 if I hadn't forgotten to put the right fuel pump on it. The pump was for 120bhp......
Things have moved on....and having another cam and fuel injection is part of it.
They ran more hp back in the day, we stick to 8500rpm to try and keep the parts inside the engine 🤣 i have been told numerous times by ex racer 10 k was normal!!
Just get a Mazda's SkyActive engine - it comes with 14.1:1 compression ratio as standard :)
cool bet it’s got a plastic cam cover ?
is that 10mm spark plugs
Had a Hillman husky
i have a husky now for doing tip runs! very versatile vehicle 👍
? Where are the proper block main bearing supports would not trust that above 8Krmp at all I would have expected more than that out of a 1040 our old 998 made 125 but then it had all the bottom end done .
The nut and stud type block strengthening kit seems to work very well, all Ian Carters engines were done this way. The blocks do look more substantial i have to agree👍
Are they DHLBs? If so, 32s or 35s?
hi yes, 45mm dhla from a lotus 907 engine.
@@thehillmanator Wow! 1040CC with dual twin barrel 45mm carbs. That's amazing. I'm running twin dual barrel 'baby' Dellorto 32mm DHLBs with 28mm chokes on my bored and stroked (73mm x 82mm) 1375CC Honda Civic EB3 street engine in my 78 Civic.
@@RestorationWatch I have a race 1040 in a Davrian, with twin DCOE 40s....I'd think 45s would be a bit too much for it?
@@betacam235 Andy is running 45s on the engine above. The Webers and the Dells are essentially the same carbs. The Dells came out 10 years later and have a few improvements, like easier access to the jets. Must be a pretty narrow power band running those bigger carbs.
@@RestorationWatch I like the dellOrtos. Had a pair on a Ford Twincam in an old Caterham, and I now have 40 on an MG Metro 1275 in a 63 year old Berkeley T60 3 wheeler which should be fun assuming I manage to get it on French plates....difficult as some crim in UK stole its ID (chassis number and reg number) put it on one of the 2,000,000 'stolen' V5cs and kindly registered it in France in 2011, so mine (on GENUINE docs) was refused as "It's already registered here".
I'll get there in the end, it's only 2 years so far.....
I agree the dellOrto is an improved Weber DCOE.
But this 14.1:1 compression ratio is supposed to be way to much. A lot of pinking and similar unfriendly things. How come this is working out. Or is the 14.1 : 1 ratio a miscalculation??
Or will this compression ratio a new step of Imp competition engine??
hi no miscalculation, definitely pushing the fuel to the limit, engine ran very little ignition advance and also rich to keep things cool, wouldn’t do another that high, very little gains.
An occasional miss fire is not a valve spring.
Agreed, my muddle lips should have said top end miss fire.
Hand held cams sucks
bought a tripod 👍