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Old 22nd November 2020, 15:27
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Mister Towed Mister Towed is offline
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Of sorts.

The story so far is that, before continuing with the bodywork I wanted to make sure that I had the engine running as it's much easier to access everything with no bodywork in the way.

As with all things Kit/Classic Car, it sounded so simple - Take an old Triumph Herald 13/60 engine that the seller showed me running so I knew it was a good one.

Modify to Mk3 Spitfire spec with a rebuilt, high compression head and a Piper 270 cam. Add a pair of rebuilt HS2 SU's and an electric fuel pump. Wire up to a new battery. Ignition on. Press starter and run engine for 20 minutes at 2500rpm to break in the new camshaft.

Only it didn't quite pan out like that. The engine turned and turned but there was no hint of it firing.

I double checked the cam timing - full lift on no.1 inlet valve at 108 degrees atdc as per Piper's spec. Check.

Valve clearances set as per Piper's spec. Check.

Compression checked on all cylinders with my compression tester, which I believe may have been manufactured in the land of China*. Check.

*A cheap piece of crap which, once I'd spent an hour trying to get the connectors to hold together under pressure showed 45psi in all four cylinders. Eek! A quick check of my Midget, which runs fine and returns 40+mpg showed exactly the same result, so it's clearly a faulty gauge. Phew.

New plugs properly gapped. Check.

Nice fat spark from each plug on turnover. Check.

Firing order 1-3-4-2 anti-clockwise. Check.

Ignition timing set to 6 degrees btdc. Check.

Carburettors rebuilt with new SU service kit. Check.

Fuel getting to carburettors. Check.

But the engine just wouldn't start.

So, I double checked everything again and decided that the only thing I couldn't check was whether the fuel was getting from the carburettors into the engine (anyone know a way to check that?).

As an experiment, yesterday afternoon I tried squirting some fuel directly into the intakes and turning the engine over again. It didn't start, but it did cough on one or two cylinders, which was encouraging, as it confirmed my suspicion that it was a fuelling issue.

So, this morning I removed the HS4 carburettors and manifold from my Midget's engine and bolted them up to the Speedster's motor.

All hoses and other connections double checked, ignition on, press the starter and...

Sorry, forgot to show you how I set up the cooling system with an old Renault header tank, so thought I'd share this pic with you.

Ahh yes, the engine.

After about two revolutions on the starter IT FIRED!

I quickly ran it up to about 2500rpm and held it there with a bolt mechanism I'd cobbled together. I also switched on the electric fan so it wouldn't overheat, eased off the choke and adjusted the revs.

As I've already said, I needed to run it for twenty minutes at quite high revs to avoid ruining the reprofiled cam, and it behaved itself impeccably, running really smoothly and sounding awesome. No clattery bug engine for my Speedster!

I was so happy I did a little dance.

After just under ten minutes I noticed that the coolant in the expansion tank had risen to near the cap, then scalding hot coolant started gushing out of the overflow on the radiator, then about a minute later I got a 360 degree shower of boiling coolant from the cap on the expansion tank.

Damn, it was boiling over so I had to shut it down.

As soon as the engine stopped running I realised what the problem was as I couldn't hear the electric fan running. A quick check of its power supply - zero voltage, a fuse must have blown somewhere in the loom.

A few seconds later I connected the fan up to another live wire and got it running. After topping up the coolant, ignition on and a press of the starter saw it fire instantly, but running it up to 2500rpm again almost immediately resulted in a shower of fluid cascading upwards from somewhere near the distributor. Damn.

It wasn't coolant this time, but oil, and I got covered in it. I looked like Red Adair after capping a gusher (google him if you're too young to remember).

On closer inspection with the engine off, the oil pressure switch housing has a take off for an oil pressure gauge, which had been capped by a previous owner with a length of plastic tube with a bolt screwed in the end. That tube had become brittle and been ejected by the oil pressure from the engine, spraying about a litre of oil all over me, the engine and chassis and all over the inside of the garage door that was open above my head.

So, to avoid that happening again I softened a new length of plastic tube with a heat gun and pressed it over the 'Christmas Tree' barbs on the take-off tube. Once that had cooled I wound a bolt into the other end, then applied some heat shrink tube over the whole thing and shrunk it down with the heat gun to lock it all in place.

After a nice cup of tea and a quick top up of the oil, I started the motor up again and it ran perfectly for a full twenty minutes at 2500rpm without overheating or losing any oil.

Success! Even if I did have one hell of a clean up job to do on the chassis, the inside of the garage door and me.

So, something's wrong with my HS2 carburettors and I'm thinking of using something else instead, maybe a single 45 DCOE. Has anyone tried one of those?

At least I now know that the engine works and I'm both delighted and relieved in equal measure.
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