13 replies to this topic

[AbingdonST]

A friend of mine has a fully functioning Coventry-Climax pump unit in its cage and he was wondering is it worth more as a mobile pump unit or is it worth more as the engine on its own for the race car restorer, are the pump and race engines common to each other? Any thoughts or views welcomed.

[David McKinney]

Others will know more, but I believe there were considerable differences between the FW (featherweight) fire-pump engine and the FWA (featherweight automotive) car version

[Ray Bell]

I've forgotten the details, but someone once told me that there aren't enough differences to prevent the fire pump engine being used...

I should think that monetary value would be higher for automotive use, while the pump could be sold separately. Not that we're actually about money here.

[Bloggsworth]

The main engine is the same; I believe/was told that the differences were centred around the fit of the pistons and rings as the pump engine was required to run flat out from start up, hence its phenomenal oild consumption, made a Wankel look frugal. The ancilliaries were the biggest external difference.

The FW had a capacity of 1020cc, the FWA was 1098cc - Whether the FWA was a bored out FW I don't know, but someone here will......... I'm just starting the stop-watch!

[ed holly]

I am just working on a genuine FWA engine out of my Lotus Eleven right now. First time I've ever had one apart. I have pulled the 1020cc one and the 1460 one apart before, but not an 1100 one. This engine is not the original for 538, which was blown up, but another FWA out of another Lotus Eleven. It was rebuilt around 1969 and had only done a couple of meetings before the car was pulled apart in 1971.

If you consider the head as the top end and the rest as the bottom end from what I can see the differences are:-

1020 has no provision for an oil cooler/filter - the FWA 1100 gets over that by taking the pump outlet external to the block through a simple drilling with a male union supported by 2 bolts through the lower block case for an oil pipe from the oil pump and about 6 inches forward of that the same arrangement to take the now external oil supply back into the block and piped from there to the vertical gallery. By doing this you can then put whatever you like in the external section, strangely my engine just had a simple rubber hose joining the two unions so it ran without a filter in its last installation, but I did get an oil cooler with it, so it did run that at one stage. It will have a filter in the line when it goes back into the car.

Except for this the blocks look the same, not sure if you need to bore the block to fit the 1100 liners to replace the 1020 ones, but that would be a simple process for a machine shop.

Obviously the crank, rods, oil pump, pistons and liners all need to be changed in the conversion, the 1020 crank is the right throw but is only cast iron and I think would not last long if high revs were used. The FW1020 and FWB1460 that were built as firepump engines have small (2/3rds size) oil pump gears in a small and unuseable housing for auto work. The oil pump in its entirety needs to be changed to a full size auto type.

The liners in the FWA have little reliefs cut into the top section to allow for valve lift and the pistons have eyebrow pockets for the same reason.

The FWB block is a different casting and has a boss on the side to attach an external oil filter directly to the block itself. FWB blocks were of course the basis for the Elite engine using an FWA crank to get from 1460cc to 1213 cc and into the under 1300cc class. To convert an FWB to a road engine is quite a simple task compared with the earlier block.

The head for the 1020 is really not useable, the ports and valve sizes are quite small and it has no provision for mounting the generator. Some late 1020 heads may have had these items cast in, but the small valve sizes means a lot of fettling to get them to car specs. . However quite a percentage of heads from the FWB pump engines do have these items cast into them, and do use the FWA / FWB / FWE valve sizes.

Have attached a couple of photos showing how the FWA gets its oil supply external so that ancilliaries can be used.

It is quite ironic that this thread has started at this time, as I literally started work on the engine pulling it apart yesterday. and took a lot of photos of it as I am very interested in the very subject of the differences myself. I have to say though, that I may stand corrected in my views above, these are my observations and knowledge through what I have read, but I am no expert in these engines. It will be interesting to see what others say as time goes on.

Ed

Edited by ed holly, 09 May 2011 - 00:10.

[David Birchall]

Its been years since I had an FWA apart but what Ed says is as I remember it. Some of the firepumps were fitted with FWB engines and rumour has it, some had the forged crank...
About all you can use from the firepump for a racing engine is the block. You can make that block into a 1220cc of course. Lovely, simple engines to work on, you just have to make sure you get the shimming of the liners right. In the seventies I had shelves full of these engines and parts.

[Bloggsworth]

105 minutes for chapter and verse - Quite slow for TNF, but I suppose it was the middle of the night in the UK.... Off to rewind my stop-watch.

[cs3tcr]

I've converted a pump to a street use engine. The cast crank is ok to 6k, but anything above that and it goes bang. The oil pump on the firepump engine can be modified to take the taller FWA gears if you add a spacer plate (mine hasnt given any trouble so far). The fittings that go through the block can be made up by a reasonable machinist. As for the head, if you source a later pump head, it should have the cast in boss on the plug side of the head, but still requires a plate welded to the front to take the main dynamo mounting plate. But, as been stated, its got little tiny valves and restricted ports. Some people say to stay away from mod'ing the pump heads, some say they're the ones to use. All i know is i've lightly worked over the head on my motor and it makes enough power to keep up with traffic.

But to answer the question on whats useable from the pump motors... the block, timing cover, cam cover, cam carrier (if you want to retain the 3 bearing cam), tappets, shims, valve keepers (need slight machinging to accept Isky springs), jack shaft, water pump, water outlets/inlets, and some minor other items. To convert one properly you would need the following: FWB or higher spec con rods, FWA/B oil pump, FWA/B cylinder head (or a machine shop and lots of $$$ to convert your pump head), liners and pistons (FWA/B/E sizes), distributor, steel timing gear, crank pulley, forged crankshaft, engine backplate, rear main seal housing and seal, automotive use oil pan, oil line fittings/hoses/oil filter/oil cooler, plus other small odds and ends (center main cap strap etc).

[David Birchall]

I've converted a pump to a street use engine.

To install in a Lotus Eleven clone that he built-from scratch! Very nice job.

I would add that the three bearing cam carrier can be converted to five bearing by a reasonably competent machinist by making split bearing blocks out of aluminium, machining flat spots on the carrier at the appropriate spacing, and bolting the bearing blocks in place, machining bearing surfaces on the cam and drilling through to the oil passageway. Bearing inserts are not required-it works well.

[AbingdonST]

The problem as always appears to be that no one seems to know anything.......
I feel like I have just taken a night school class in FWA engine building. Outstanding knowledge Gentlemen, I think I will encourage him to retain it as a functioning pump unit, you never know, the way the climate is going it could be worth more as a pump than a race engine. It may one day save our toys from the advancing flood waters, now as a back up plan what did I do with that Guzzi.......

Edited by AbingdonST, 09 May 2011 - 16:58.

[Tuboscocca]

I can only recommend:

Des Hammill COVENTRY CLIMAX Racing Engines (Veloce 2004).
As he describes the various FW types, one can see the differences between the types and the development (not all of course)..

Best regards Michael

[AbingdonST]

I can only recommend:

Des Hammill COVENTRY CLIMAX Racing Engines (Veloce 2004).
As he describes the various FW types, one can see the differences between the types and the development (not all of course)..

Best regards Michael

Many thanks, will get my friend Simon to read it, then he can decide what is best for the motor. Still leaning toward retaining as a pump.

[cs3tcr]

Here's a brief slideshow of my pump motor, if anyone is interested:

Roderick's Coventry Climax slideshow

[raceannouncer2003]

Here's a brief slideshow of my pump motor, if anyone is interested:

Roderick's Coventry Climax slideshow

Well done! Will you be bringing it to the Historic races at Mission June 11-12?

Vince H.