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| Smoking!! |
Keith was the first europeen to to break 9s for the 1/4mile with a 8.93 run
got this info from a thread on the Triumph Rat forum
After our successful season in 1975 Mick Hand, Angus McPhail and myself decided that due to the poor handling of the old bike which kept trying to throw me off we would build a new bike for the 1976 season.
We had already used the 76mm short stroke crank in the original bike after the eight second engine grenaded itself at Aintree caused by a broken rocker and all the boost going into one cylinder. The stock used Triumph alloy rods gave up the ghost and there wasn’t much of the motor left.
We also decide that for the new season we would need a more reliable blower than the Shorrocks C75B which was being run far above its safe limit trying to get more power.
So Gordon Allen of Allen Engineering made the EN40B billet crank and steel rods to Angus’ spec. Being made from a 6” billet instead of 7” meant the centre flywheel, which is a complete circle runs in an elliptical fashion in the cases to obtain the balance factor. For fine tuning there is a 1” screwed in bung that can be wound in or out to get balance. The crank is very rigid and can run to 9000 rpm without any problems and is very smooth.
The three of us were invited down to Weslake Engineering in Ryde for a look round and they kindly donated a cylinder head and barrels off an 850 motor for our use. They also supplied some RR56 alloy piston blanks.
Mick machined up the pistons to 79mm an aquired MTP quality rings for them. These combined with the 76mm stroke of the crank resulted in a capacity of I believe 748cc’s.
Being as the Weslake motor used the same points of origin for the cams as the old Triumph motor it meant the push rods leant outwards on the new motor instead of inwards as the Triumph.
After initial runs the Weslake head proved to be weak in the casting behind the valve seats for 80% nitro and subsequently Pete Davies of Puma Engineering fitted steel skulls in the head with the valves cut directly into the skull avoiding any more loose valve seats. We also fitted Cosworth DFV exhaust valves which are a lot better quality than the originals but being slightly shorter meant some small hardened valve caps are used to make the length up and keep the operating angle of the rockers correct.
Angus beefed up the original 6T crankcases and mounted the crank on a 50mm diameter Ena needle roller bearing on the drive side and back to back ball bearings on the timing side.
The cams are stock EN3134 items running standard Triumph 34/55 and 55/34 timing. The final drive sprocket is mounted on the end of the crank and is not splined but drives through eight Allen bolts which pass through the blower pulley and sprocket into the crank.
Bert Hopkinson, a friend of Mick was commissioned to produce the two speed gearbox and Ag decided it should mount fore and aft in the frame to avoid the twisting effect generated by the Norton box mounting top and bottom.
I obtained a Wade 900cc cabin blower from Freddie Cooper which basically is just an air pump so for us to put a fair amount of fuel through it Mick removed the labyrinth seals and installed neoprene oil seals in their place plus originally the shafts were only “stump” shafts. Mick removed them from the rotors and machined the rotors deeper to accept stronger, longer shafts. With this setup the blower revs to 12000 rpm without fuss and produces 30 lbs of boost. It actually made 33 lbs but we made a new pulley to bring the boost down to 30 psi.
A magnesium Jaguar size back wheel was donated by Minilite and Mick made up a wheel carrier to adapt it to a bike. Angus obtained some Ford 10SE con rods and cut the tops of so the clamp end could be adapted to carry the rear wheel spindle giving maximum rigidity to the assembly.
That meant with the motor, gearbox and rear wheel we were ready to produce a frame. Mick made up all the fittings and engine mounts and Angus brought the whole thing together in his workshop over one weekend.
I bought a set of MP forks and a Honda tls front wheel and the rolling chassis was finished.
Ag made up the exhaust pipes and for ignition we ran the old polar induction Lucas magneto off original bike
We also decide that for the new season we would need a more reliable blower than the Shorrocks C75B which was being run far above its safe limit trying to get more power.
So Gordon Allen of Allen Engineering made the EN40B billet crank and steel rods to Angus’ spec. Being made from a 6” billet instead of 7” meant the centre flywheel, which is a complete circle runs in an elliptical fashion in the cases to obtain the balance factor. For fine tuning there is a 1” screwed in bung that can be wound in or out to get balance. The crank is very rigid and can run to 9000 rpm without any problems and is very smooth.
The three of us were invited down to Weslake Engineering in Ryde for a look round and they kindly donated a cylinder head and barrels off an 850 motor for our use. They also supplied some RR56 alloy piston blanks.
Mick machined up the pistons to 79mm an aquired MTP quality rings for them. These combined with the 76mm stroke of the crank resulted in a capacity of I believe 748cc’s.
Being as the Weslake motor used the same points of origin for the cams as the old Triumph motor it meant the push rods leant outwards on the new motor instead of inwards as the Triumph.
After initial runs the Weslake head proved to be weak in the casting behind the valve seats for 80% nitro and subsequently Pete Davies of Puma Engineering fitted steel skulls in the head with the valves cut directly into the skull avoiding any more loose valve seats. We also fitted Cosworth DFV exhaust valves which are a lot better quality than the originals but being slightly shorter meant some small hardened valve caps are used to make the length up and keep the operating angle of the rockers correct.
Angus beefed up the original 6T crankcases and mounted the crank on a 50mm diameter Ena needle roller bearing on the drive side and back to back ball bearings on the timing side.
The cams are stock EN3134 items running standard Triumph 34/55 and 55/34 timing. The final drive sprocket is mounted on the end of the crank and is not splined but drives through eight Allen bolts which pass through the blower pulley and sprocket into the crank.
Bert Hopkinson, a friend of Mick was commissioned to produce the two speed gearbox and Ag decided it should mount fore and aft in the frame to avoid the twisting effect generated by the Norton box mounting top and bottom.
I obtained a Wade 900cc cabin blower from Freddie Cooper which basically is just an air pump so for us to put a fair amount of fuel through it Mick removed the labyrinth seals and installed neoprene oil seals in their place plus originally the shafts were only “stump” shafts. Mick removed them from the rotors and machined the rotors deeper to accept stronger, longer shafts. With this setup the blower revs to 12000 rpm without fuss and produces 30 lbs of boost. It actually made 33 lbs but we made a new pulley to bring the boost down to 30 psi.
A magnesium Jaguar size back wheel was donated by Minilite and Mick made up a wheel carrier to adapt it to a bike. Angus obtained some Ford 10SE con rods and cut the tops of so the clamp end could be adapted to carry the rear wheel spindle giving maximum rigidity to the assembly.
That meant with the motor, gearbox and rear wheel we were ready to produce a frame. Mick made up all the fittings and engine mounts and Angus brought the whole thing together in his workshop over one weekend.
I bought a set of MP forks and a Honda tls front wheel and the rolling chassis was finished.
Ag made up the exhaust pipes and for ignition we ran the old polar induction Lucas magneto off original bike
. 
Here is a short interview with Keith Parnell on the Eurodragster.com website
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