Print

[Alan Drover]

On my way to the pub lunchtime (the dog insists on going) at the nearby Shell station was a hot rod. I could see only the right hand bank of the flat head Ford V8 but the head was ally with 8 spark plugs and the visible distributor had  a multitude of leads coming from it. The exhaust manifold was a 3 branch so I reckon the middle 2 exhaust ports were siamesed. The owner told me it was a racing twin spark conversion and it was supercharged and nitrous oxide injection. That would  give the yoofs in their backfiring electronically controlled junk something to think about. W hen he drove off I hoped he would give it full welly but he didn't.
Further along the way to the pub I saw a Series 1. I gave an enthusiastic thumbs up and got a responsive wave from the driver.

[Craig T]

My sisters partner is mad about hotrods. He has a 1932ish three window coupe with a 351 Ford Cleveland, 3 speed auto engine and box in it. Rear axle is a Ford 9" but the front is a cast beam axle with a transverse leaf spring. Chassis is a somewhat flexible twin U-channel affair.

I have seen those twin spark heads around on flatheads but not too common. You can kind of see what they were thinking though in the picture below as the combustion chamber is a funny shape, you now get one plug over the top of the piston as before but another over the valve area. Must make it ignite a bit faster right?

And you are correct, the centre exhaust runners that are cast into the block are shared on the centre cylinders. Makes the flathead sound a bit different to other V8's but not a unpleasant sound like the TVR V8 that had a flat plane crank. That sounded like two rattily Ford 4 cylinders fighting to run against each other!

[Alan Drover]

Thanks for that Craig. Interesting combustion chamber layout. The rod I saw had a manual box.

[w3526602]

I always understood that pre-war Rolls Royce and Bentley engines had double ignition ... two plugs per cylinder.

I'm less confident about them having two magnetos, or two coils, or one coil and one magneto. It's been probably forty or fifty years since I even thought about it.

I have a vague memory of sitting in a Tiger Moth ... goggles, leather helmet, and sitting on a parachute, listening to my school's Art Teacher saying to the bloke who was going to swing the prop .... SWITCHES OFF  .... SUCKING IN ... SWITCHES ON ... CONTACT .... CHOCKS AWAY.

Note .... SWITCHES was in the plural, which might indicate dual ignition.

Croydon Aerodrome was described as not having a runway, although memory says there was certainly some concrete, and I think it was TRANSAIR who used to zig-zag their DC3s, between the tall street lamps on the road outside the "lido", on the street opposite.

When I was about 7, I and a gang of similar lads, watched a (presumably) DC3 fly low overhead, and crash into the trees near the top of Sanderstead Hill. The national newspapers reported that the 90 passengers werre all killed.

602

Probably 1954 or 1955, Croydon Aerodrome

[Peter Holden]

Rolls Royce Merlin engines all had twin ignition systems including twin magnetos

Peter

[w3526602]

Hi,

The faster you turn a magneto, the bigger the spark.

I don't know if it's related, but I once had to do some work on an RAF Coventry Climax trailer fire pump. I was puzzled by the (assumed) mechanical advance system appearing to twist the wrong way.

Somebody better informed than myself told me that it was an "impulse" starter.  As the engine reached TDC, the magneto shaft "jumped" forward a few degrees, causing a bigger spark where and when it was needed. No need to frantically hand crank the engine.

Whatever, it was still a b***** to start. Not my problem! We had returned the pump to a maintenance unit (RAF Stafford, probably) I was given a Standard Vanguard, at RAF Faldingworth (North of Lincoln), told to collect my tool kit, and go and bring everything up to scratch.  I wonder why they always picked on my for those sorts of jobs?

Not a problem .... they even sent me to RAF Biggin Hill (only 20 minutes from Mum's, so I could live at home) for 6 weeks, to prepare stored vehicles for the Battle of Britain Air Show. It was on my way home from Biggin Hill, that I came across the 12 year old lad who had been strangled by a pervert, and left for dead. That gave me another week at home, as I was needed to give evidence at the initial court hearing at Bromley Crown Court.

The boy's eyeballs were completely blood-shot, so it had been a close thing.  I was not aware, at the time, of the significance of that.

The Sergeant at New Addington police station asked what he could do for me.

"Somebody duffed up the kid, and nicked his bike!"

"What happened son?"

"Somebody strangled me, and stole my bike!"

"Did they now? Come into the back office!"

The Perv had previous. The boy knew his first name, and birthday. The police arrested him that evening. He was in the middle of painting his bike a different colour. The boy's bike was found hidden in the woods.

"ATTEMPTED MURDER?  Thank God! I thought I'd killed him!"

602