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Old 07-05-22, 11:36 AM
Geoff Dowdle Geoff Dowdle is offline
Join Date: Jul 2008
Location: Sydney, Australia
Posts: 408


The carburettors fitted to your engine were originally fitted to an AC Ace or Aceca Bristol with 100D or 100D2 engine. The jettings for these and original Arnolt Solex (32BI) are similar.

B32PBI-6 Venturi /Choke 28mm,Main Jet 125, Air Correction 190,Pilot Jet 55, Pilot Air Bleed 1.0, Emulsion Tube 10, Needle Valve 1.5 ,Float Level 16mm , pump jet 95

32BI Venturi 28, Main Jet 135, Air Correction 240, Pilot Jet 50, Pilot Air Bleed 1.0, Emulsion Tube L24 (special), Needle valve 1.5 , Float Level 16mm
Pump Jet ( None fitted)

Your Arnolt 3052 in the early 70s was fitted for a while with a D or D2 engine
but was later replaced by the original BS1 Mk2/253. Have you checked the actual engine numbers stamped on the block close to the top starter motor bolt and on the head on two raised bosses on the distributor side.
Pls advise those engine numbers.

Over the years I have had two D2 engines fitted in a AC Ace and Bristol 400 .
For road use I could not get the engines to run correctly until I blocked the pump jets . The pumps on your Arnolt have been disconnected and I suggest you leave them like that .
From memory I increased the size of the main jets from 125 to either 130 or 135 and increased the air correction jets from 190 to about 210 .
I covered more than 60,000 miles in my 400 with that engine , which always ran strong and delivered 28 - 29 mpg touring at about 70 mph.

I also suggest you have the Arnolt dyno tuned or at least get the use of a mobile gas analyser to confirm if the engine is running rich or lean .
Over nearly 70 years most of these engines have been modified with different compression & valve timing and of course the fuel today is different to the 50's.

I hope this is of some help

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