Ian Cooper Posted September 30, 2020 Report Share Posted September 30, 2020 Hi, I need to ask a dumb question. My CD150s have the single 'cold start/choke' on the front carb, with connecting pipe to the rear carb, There is a 'press and twist' Summer/Winter screw but try as I might I cannot find a simple instruction for this two position screw, in the official workshop, Haynes workshop or GT6 handbook. My guess is push in and twist (90°) for 'Summer' and twist and release (out) for 'Winter' but it could be the opposite. I don't understand why this is not stated clearly anywhere, that I can find, and an explanation of what is actually happening, when operated, would be good? Any light would be helpful. Thanks Ian Link to comment Share on other sites More sharing options...
Jeffds1360 Posted October 1, 2020 Report Share Posted October 1, 2020 I have read somewhere that "horizontal" is winter and turn 90 degrees for summer. I understand that the action enriches the mixture when rapidly accelerating in winter. Does not affect general tuning. Hope that helps Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 1, 2020 Report Share Posted October 1, 2020 no the sprung and twist winter summer knurled brass thing is just a stop to reduce full choke use in summer push and turn it 90 deg and it pops back allows more choke cam travel for richer winter choking its a simple mechanical adjustable stop has no effect or connection with any mixture or base settings Pete Link to comment Share on other sites More sharing options...
Ian Cooper Posted October 1, 2020 Author Report Share Posted October 1, 2020 Hi. Thanks once again folks, pretty much what I guessed, just don't understand why there's no simple explanation in any documentation? Link to comment Share on other sites More sharing options...
Jeffds1360 Posted October 1, 2020 Report Share Posted October 1, 2020 From the Stromberg owners manual :- C) Winter and Summer Settings: Your new Stromberg 97 carburetor is supplied with the accelerator pump rod in the W (Winter) position on the throttle linkage. The S (Summer) and W settings partially determine the volume of enrichment fuel discharged into the venturi when the accelerator pump is rapidly depressed. The linkage will discharge greater enrichment in the W position. The correct setting should be determined by the driver to suit local operating conditions. If the vehicle tends to stumble on acceleration, try changing the rod to the other position, then try the acceleration test again. Link to comment Share on other sites More sharing options...
NonMember Posted October 1, 2020 Report Share Posted October 1, 2020 3 minutes ago, Jeffds1360 said: Your new Stromberg 97 carburetor And how does a "Stromberg 97" compare to a 150CDSE? 4 minutes ago, Jeffds1360 said: is supplied with the accelerator pump rod in the W (Winter) position on the throttle linkage. The CD series don't have an accelerator pump Link to comment Share on other sites More sharing options...
Jeffds1360 Posted October 1, 2020 Report Share Posted October 1, 2020 Oh well, I've dug a hole It was just something I read recently. Thought it might help. 🤷♂️ Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 1, 2020 Report Share Posted October 1, 2020 that is not for CD strombergs thats down drafts with an accelerator pump ie as below it is quite common on many makes of downdrafts the pump stroke has a rotating stroke stop ,(has two heights ) but thats not the case on any triumph down drafts and there is only the dashpot damper on a CD to enrich acceleration flat spots, no pumps heres a pic of a 97 its ailen to most UK cars the adjustment on this thing is from moving the pump rod ball joint not a nice UK twiddle and done idea Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 1, 2020 Report Share Posted October 1, 2020 From an online manual on CD and CDSE models: "Choke limiting spindle adjustment 0 winter setting, stop cross pin in horizontal slot in casting. Summer setting, depress spring loaded pin and turn 90°." So it seems you depress and turn for summer, as Ian says back in the first post. From this online manual: https://www.howacarworks.com/fuel-systems/adjusting-a-stromberg-carburettor "Some Strombergs have a two position screw to limit the use of the choke according to the season. It has a spring under its head. Set it with the spring compressed for summer and the tension released for winter (only necessary in freezing weather)" If I have one on any of my Strombergs, I've never seen it and furthermore never used it... 1 Link to comment Share on other sites More sharing options...
Ian Cooper Posted October 1, 2020 Author Report Share Posted October 1, 2020 Thanks Colin, now why didn't Triumph include that simple line in their docs?? Ian Link to comment Share on other sites More sharing options...
Iain T Posted October 1, 2020 Report Share Posted October 1, 2020 6 hours ago, Colin Lindsay said: If I have one on any of my Strombergs, I've never seen it and furthermore never used it... I have one on my front carb, possibly only on the CDS version? Iain Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 1, 2020 Report Share Posted October 1, 2020 it was common on later Rootes cars dont know when triumph added it more CDSE/CD3 era. shown on some gt6 at Burlen's Petehttp://zenithcarb.co.uk/carbspec/carburettor/spares/id/4042/ Link to comment Share on other sites More sharing options...
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