Our Elva sports racer arrived battered, broken and missing the original drivetrain: no intake manifolds, no Weber side-draft carbs, no charging system, no header, no exhaust system.
Again, we had plenty of work to do.
Coventry Engines: A Racer’s Favorite
Elva originally equipped our Mk VI with a Coventry Climax engine, a racer’s favorite for generations. The story dates back a hundred years, with the Coventry company first making powerplants for light cars, tractors, fire pumps, generators and the like.
After World War II, Harry Mundy (previously of Alvis, ERA, Morris and BRM) and Walter Hassan (previously of Bentley, ERA and Jaguar) were brought in and, by 1950, had designed a lightweight, all-alloy, overhead-cam engine for portable fire pump use. This engine, dubbed the FW for Featherweight, caught racers’ attention thanks to its lightness, durability, and high output relative to its displacement.
Soon after, Coventry–now called Coventry Climax–increased displacement from 1020cc to 1098cc and modified the engine for automotive use, and greats like Stirling Moss and Lotus’ Colin Chapman started running it. The designation was tweaked, too, becoming FWA–the A signified automotive use. A 1460cc version, the FWB, was released soon after.
In addition to receiving new names, these FWA and FWB engines also replaced the cast cranks with forged units that could handle higher engine speeds–about 6000 rpm or so. The intake and exhaust ports were enlarged, too, for better breathing.
These engines also featured mounting points for a charging system as well as an oil filter. They also received oil pans designed for automotive use.
Our Elva came into our lives with a Coventry Climax engine, and although it was a simple machine, we decided to bring in an expert for its rebuild. So we carried it up to Ted Wenz and his crew at Savannah Race Engineering.
Ted inspected our engine and reported back: Our engine was in nearly perfect condition. But that didn’t matter because we had a FW pump engine, not the correct FWA automotive engine. Cue the sad trombone.
One bit of good news, though: Our car came with a new-in-the-box race cam plus a five-bearing cradle. Both are correct for an Elva race engine.
Building a Period-Correct Engine
1. Ted Wenz of Savannah Race Engineering–the company is now owned by fellow vintage racer Andy Greene–inspected our Coventry Climax engine. It looked great, but it wasn’t the right one for our application. We had a pump engine, not a race car engine.
2. Even our original engine block was in good shape, but without an oil filter housing and just 1020cc of displacement, it wouldn’t do us much good.
3. The pump engine’s alloy head and valves were also in good condition, but the valves were too small for race applications.
4., 5. One good bit of news: Our project came with a brand-new race cam and the required five-bearing cam holder. The pump engines came with three-bearing cam holders that aren’t suited for high-rpm use.
6. Lots of legwork turned up the correct FWA engine, which was rebuilt top and bottom to original specs.
7., 8. Since we were replacing the original mechanical fuel pump with an electrical model, we had to fabricate a block-off plate.
Comments
wspohn
SuperDork
5/3/22 11:23 a.m.
Unless you happen across an FPF engine for sale, you could always try a Rally Imp engine -
https://www.imps4ever.info/development/engine-development.html Pretty reliable and you can get quite good power out of them. And you could always tell yourself you were competing for Index of Performance....(they were getting around 100 bhp out of them).
I haven't priced what the correct engine for the car would cost today but it is probably pretty substantial. In the old days when I started racing I turned down a bobtail Cooper Climax for around $2000 - this was back when they were just 'old used up race cars'. 
Heck, I should have been trying to buy every 4 cam Porsche engine I could find when they cost what in retrospect was a ridiculously low price - best automotive investment I can think of.
I'm surprised you didn't have hte FWP block modified. It's essentially the same block as the FWA, albeit with smaller liners. To convert an FWP block all you have to do is punch two holes in the side of the block for the oil line fittings and bore it to take the bigger liners. From what I recall you can even go to the FWB sized liner to make it an FWE if you stick with the stock FWA crank. I've even been told with modern rods, you can fit the FWB crank to the FWP/A blocks to make it FWB size.
I assume the reason for sourcing an FWA was the crank and other bits (oil pump, probably had later FWB type rods, etc).
I do have a question about the cylinder head in the picture, the last FWA cylinder head I had, had the dynamo mount cast into it. The head in the pic looks like it's a bolt on piece. Is the head really and FWA head or is it a modified late FWP head (with the casting on the side for the dynamo mount)?
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