dtn_bolt_on

Downton Bolt On Kits

© Barry Hawkins / MK1-performance-conversions.co.uk Do not copy or duplicate without writen permission

Each of the "Bolt on kits developed by Downton went through the same careful development process, this is described by long time Downton employee Mr Barry Hawkins.

A Downton, Bolt-on:

Always carefully overseen by Daniel Richmond.

When a new BMC model came out, say a new 'A' series, Downton would take the engine apart and if the car was going to remain as a demonstrator the crankshaft/flywheel assembly would be balanced, the engine would have the head faced to increase the compression, say 10-1 then ground and ported by George toth and the valves would have their heads machined in the machine shop.

George would also skilfully reseat the valves. The head would then go to Fred Stokes for careful calibration (with pipet and parrafin oil) then onward for assembling, at which time all Downton heads had the end top face stamped by Fred with comp ratio and referance number.

Jim Penton (foreman welder) would have the car and by trial and error carefully workout the shape for a three branch exhaust manifold then onto the rest of the exhaust system (silencers where bought in from Burgess silencers in Leicester). All the bolt-on Downton kits used BMC cast aluminium inlet manifolds. George in the head shop ground them out to match the inlet ports on the head and they had location pins fitted. For the competition engines Jim would produce an inlet manifold in tube for Robin Fearon, who would then fit linkages and say for example, twin H4 SU carbs, heat shields and aircleaners.

The distributors where usually changed for non vac types.

All this process would take a couple of weeks, sometimes the guy's would stay on into the evening until the job was done with Daniel carefully watching every move.

The car would then all be put back together and Daniel would try the car with the foreman machanic on our test route complete with fifth wheel for speed accuracy. This was always a touchy time, Daniel had a good ear and a fine touch with engines, so nothing would ever get by unless it was absolutly correct.

Eventually all the bits would come off again and jigs made and and if necessary an aluminium inlet manifold cast (an outside company job).

The completed new kit would then be fitted and again go through a full Daniel test and again Daniel would be up and down the test route time and time again each time testing various SU needles etc. Not until he was fully satisfied did we all relax a little.

At the end of this prosses I would get all the parts together and do the costing and make the specification sheets up. Daniel and Bunty alway trusted me with this side of the business.

Downton never cheated as far as performance figures were concerned.

Please note over my time at Downton some of these jobs where done by differet people (apart form the very much liked Fred Stokes who was older than the rest of us) so every time you look at a real Downton head you will know it was Fred that put those numbers on the end of it

Downton Brochure Archive

A selection of brochures for Downton "Bolt on" conversions

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