Some project photos

[Alan Smith]

I know how much people here like looking at photos so having just got around to setting up a photobucket account I thought I'd share a few. More fabrication than machining strictly they show a sequence in the manufacturing of an inlet manifold to allow the mounting of motorcycle flat slide carbs on my sports car.



This is the back plate cut out of 0.250" tooling plate.



This is the mandrel, carved out of a lump of ally. I turned down some ally tube to appropriate i/d and o/d, annealed it, greased up the mandrel and pressed it into the tube. A gentle dressing over with appropriate hammers and the tube took on the shape of the mandrel.



This was a trial weld onto an offcut of tooling plate.



Bringing the shaped inlet runners/spigots together with the back plate on a steel jig ready for welding.

More photos to follow.

[Alan Smith]

The carbs mounted.




And the vehicle in question, although in fact this photo was taken before the M/C carbs were put on.

[Spin Doctor]

The carbs mounted.




And the vehicle in question, although in fact this photo was taken before the M/C carbs were put on.

Is that an original or a copy of the Lotus 7. Caterham perhaps?

http://en.wikipedia.org/wiki/Lotus_Seven#Replicas

A Super 7 for the 21st Century

http://www.arielatom.com/?gclid=CKTu...FRa_WAodpim6Sw

[speedsport]

I hope you will also tell us all about getting the carbs jetted correctly.

[A.K. Boomer]

Nice work Allen, class act fabrication, good looking welds.

Are those vacuum operated slides? if so thats good stuff, they cover the range very well, its carburation in about its most efficient form... Im guessing they are because I see where a shaft leads ahead of the slide, so it most prob. has a typical butterfly plate for controll and then the slides take over by sensing engine load and RPM and butterfly pos. ?

[Fasttrack]

Yeah what year is that? Wasn't caterham bought out by lotus in the early 90's? I dunno i could be way off ...

[Alan Smith]

Yes it's a Caterham. An HPC (High Performance Car) with a Swindon(Racing Engines) 218 Vauxhall 2.0XE engine. Caterham Cars bought the manufacturing rights from Lotus in the early '70s. We just (September 6th) celebrated the 50th anniversary of the marque, not bad for a car that can still out accelarate Porches and Ferraris!!

I have to confess that the welding is not mine. I'd dearly love to have tig but it's way out of my budget with a queue of other desired toys taking presidence. I'm fortunate to have a specialist welding shop fairly close at hand and the guys that run it are keen bikers and sympathetic to my nutty ideas.

The slides are cable operated, not the CD (constant depression) vacuum type. Very simple, but beautifully made and can give precise metering. Setting them up was a bit of fun. The guys at the rolling road I use were not really familiar with this type of carburator so we had to hunt around to find a motorcycle tuner to come and give a hand. Once we all got together we got it set up in a couple of hours. RR printout is below.



Bear in mind this car weighs about 600Kgs, 201 BHP really shifts it!

[topct]

Those carbs work better with an airbox in front of them. The distance from the air horns to the slide is very short so something to quiet the air in front of them is a power maker. Or longer horns at least. Those little short ones are made to be inside the air cleaner box.

Nice job.

[sidegrinder]

Those look similar to some Keihn FCR (39mm) carbs I had on my Ducati 900SP back in the day. Some days I sure miss that bike...

[Alan Smith]

Those air trumpets are what came with the carbs for M/cycle applications. I made up some much longer aluminium air trumpets and had some spacers waterjet cut out of 1" ally plate. I think that gives an inlet tract length of 14.5" to the back of the inlet valve, great for a good torque curve.

The carbs are Keihin FCR 41s, as I said above , beautifully made.

One other job that had to be done was getting a new throttle spindle made up. This had to be farmed out as I don't have a mill or anything capable of precise drilling/allignment.

Talking of airboxes, this winters project will be an airbox. As run at the moment there is a foam Pipercross sausage filter which is outside of the bonnet (hood). The induction roar is horrendous when giving it beans and I'm sure contributing to my increasing deafness, so this box will hopefully attenuate the noise and will take air from a remote air filter from within the engine bay. Hopefully I can direct a stream of cool air in the filters direction.