What a lovely little engine.

Helped to strip one of these last night. It came with a basket case project and hasn't run in years. Being all alloy and not having leaked a great deal of oil it was a furry mess outside, but we suspected it might be a good one so went ahead anyway.
All the ancillaries came off and this included a nice oil takeoff head for a cooler and a twin choke weber on a manifold. Good so far.

Up onto the bench and the rocker cover came off. Lovely and clean inside with the cam looking very fresh with no visible wear. Can't identify it yet, but we found a vernier pulley. This engine obviously has been built for a purpose.

Next off was the head which much against expectations came off without issues. They are supposed to weld themselves to the head studs. This one just came straight off.

Turned the head over. Bit of furring on the casting where some valves had been opened, but not bad - and another result. It's a big valve head.

This is looking quite good.

Onto the bottom end and out with the verniers again to check the bore.

It's a 998cc
You really don't expect this, in all probability, it would have been an 875cc.

Truned the block over and off with the sump. A lowly pressed steel affair that does not sit at all well with all of those nice alloy castings.

Off it comes and what do we find ?
First of all, I really did not know that an Imp bottom end was a 3 main bearing job. Remember, these will rev to 8000rpm easily. Not a lot compared to a bike, but this is an engine with its roots in the 1950s (British Trident - over to you here for expert knowledge).

Anyway, what else do we find. Machining marks on the crank journals and webs and drilling and polishing to the conrods. Off with the flywheel and drilling to the reverse of the flywheel. So it has had the bottom end lightened and blanced as an assembly which is another very welcome find.

Off with the mains and out with the crank.
Front main bearing actually forms part of the crankcase and the crank is set deep within the crankcase. This was another nice touch for me. It must add to the stifness of the bottom end.

And there we were left with a bare block which the wind was trying to blow away as it was so light.

I don't imagine any of you will be contemplating an Imp engine any time soon, but I for one was always curious about these famously revy little engines and it was real treat to get inside one for a poke about. Especially one which has seen some attention on the past.
We reckon it's good enough to just clean up and reassemble.

Cheers

JF

might be a good engine for the new single seater too. The do seem to be quite popular, I still see quite a few Imps driving around up here.

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Originally posted by zilspeed

And there we were left with a bare block which the wind was trying to blow away as it was so light.

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Yes indeed there was the Coventry Climax connection.

They are indeed lovely little units, keeping me happy in R40 for many years. It is very difficult to believe that the engines were out there in the 60's. Here's my (now sold) Clan (now doing something with a chap in Scotland),
http://uk.youtube.com/watch?v=uWoLpDMZFts
I'd even buy it back now, which says it all.

The engines themselves are incredible, yep, that 3 bearing crank will take a pounding. You can stroke them, add a spacer on the block, get it up to 1120cc etc., etc., only problem is cost. A 998 on an R20 cam, snorting through 40's is a great classic combination. It's just way outclassed now compared to other powerplants of that size, but still a great historic toy.

If I remember correctly they were even used on forces fire barrows to run a water pump for fire fighting, very powerful pump which would pick a person up holding the hose with a 3/4" branch on the end, great fun would be had inching the revs up and seeing the shocked look on the hose mans face as he realised that he was starting to fly.

Regards

Bob

yep - you remember correctly - there was a shed load of climax engine pumps on the bay last year.

quote:

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Originally posted by motorcycle_mayhem
They are indeed lovely little units, keeping me happy in R40 for many years. It is very difficult to believe that the engines were out there in the 60's. Here's my (now sold) Clan (now doing something with a chap in Scotland),
http://uk.youtube.com/watch?v=uWoLpDMZFts
I'd even buy it back now, which says it all.

The engines themselves are incredible, yep, that 3 bearing crank will take a pounding. You can stroke them, add a spacer on the block, get it up to 1120cc etc., etc., only problem is cost. A 998 on an R20 cam, snorting through 40's is a great classic combination. It's just way outclassed now compared to other powerplants of that size, but still a great historic toy.

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quote:

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Originally posted by zilspeed

quote:

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Originally posted by motorcycle_mayhem
They are indeed lovely little units, keeping me happy in R40 for many years. It is very difficult to believe that the engines were out there in the 60's. Here's my (now sold) Clan (now doing something with a chap in Scotland),
http://uk.youtube.com/watch?v=uWoLpDMZFts
I'd even buy it back now, which says it all.

The engines themselves are incredible, yep, that 3 bearing crank will take a pounding. You can stroke them, add a spacer on the block, get it up to 1120cc etc., etc., only problem is cost. A 998 on an R20 cam, snorting through 40's is a great classic combination. It's just way outclassed now compared to other powerplants of that size, but still a great historic toy.

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Was your Clan on throttle bodies ?

It's just that I know soemone up here who has / had a yellow Clan on throttle bodies and minilites.

Incdentally, there is a Clan relevance regarding the Imp engine I was helping with.

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That's the car I was talking about Doug. There's a surprise ;-)


The one on the video under this one on youtube.
Only with Ian Longford driving it.
(Although strangely, he didn't manage to lock up the front wheels into the top corner for a change.)

I think the Clan was more suited to Joe than the Phantom - which is for sale again......

VAKattack!
Yep, it's a beautifully put together car (I did it). I still have the moulds for the front end, the roof and floor (I had to add the bulge to get 6'2" in plus helmet). The crossmember, too, was all my own construction. The car broke across the floor when it landed after going seriously airborne (I hit a bank and launched the thing).
Didn't realise it'd been sold on, if it does come up again, let me know. I have a partially built GSXR1000 subframe to slot it the rear. Only sold it (sob..!) because with so many other cars around the house, just no room.

The origin of the Imp engine was the same fire pump engine that became the Coventry Climax engine that powered Jim Clark to World Championship.

quote:

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Originally posted by motorcycle_mayhem
VAKattack!
Yep, it's a beautifully put together car (I did it). I still have the moulds for the front end, the roof and floor (I had to add the bulge to get 6'2" in plus helmet). The crossmember, too, was all my own construction. The car broke across the floor when it landed after going seriously airborne (I hit a bank and launched the thing).
Didn't realise it'd been sold on, if it does come up again, let me know. I have a partially built GSXR1000 subframe to slot it the rear. Only sold it (sob..!) because with so many other cars around the house, just no room.

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What does he have now Doug ?

The Elan is with Derek Hastings is it not ?

God Grief - was Joe still racing a Clan till last year?? I remember reading about him 20 years ago in a rather battle-scarred grey/blue one which he'd managed to keep running on less what i spend on ciggies in a year..

The Climax/Imp engine is one of those classic engines overshadowed by the likes of the crossflow - despite the fact it weighed sod all. Replaced in the fire pumps by Reliant 850's (the stalwart of the 750MC for many years) - another all alloy lump (there's a pic somewhere with a sales director holding a fully dressed Reliant lump at waist height with ease...)

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The origin of the Imp engine was the same fire pump engine that became the Coventry Climax engine that powered Jim Clark to World Championship

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Complete history of the company and engines here
http://en.wikipedia.org/wiki/Coventry_Climax

I had a Coventry Climax firepump with the FWB 1460cc version of the engine

Sold it to a guy who was going to use it in a historic Lotus single seater.