TRnorm Posted February 12, 2015 Report Share Posted February 12, 2015 I need to learn a little about the cam arrangement on a pair of SUs - not so how much about how it works, but how to specify the correct cam. How did I get to this point? Well, when I started this project my basket case had Strombergs, and I wanted SUs. I found a pair with waxstats et al (off a saloon I guess) and sent them to Burlin to be refurbished, changed from waxstats and they returned all beautifully polished and mounted up on my TR manifold. I said they were for a TR4 but not sure if that was enough. Since firing up last August I've suffered from overly rich mixture and a reluctance to start on occasions. The latter I have finally realised is that with the choke out there is no engagement of the cam to increase the air flow (I guess the linkage etc is different to the TR). Simple really - the snail action of the cam is very very shallow - and as usual it was my son who fathomed it out! So the question is....Is there any reference literature that explains What is What, or alternatively, What degree of lift to the throttle should I be looking for with the choke say pulled fully out. Worst comes to the worst I could make up an appropriate pair of cams if I had this info. As usual, any advice much appreciated. Norman Quote Link to post Share on other sites
RogerH Posted February 12, 2015 Report Share Posted February 12, 2015 Hi Norm, see item 55 http://www.moss-europe.co.uk/shop-by-model/triumph/tr2-4a/fuel-system-induction-controls/carburettors-manifolds/carburettors-air-cleaners-h6-su.html There should be an adjuster screw that gives the amount of throttle opening you may want. However, what is to stop you opening the throttle slightly with your foot. I appreciate this will not help tick over when warming up. Roger Quote Link to post Share on other sites
TRnorm Posted February 12, 2015 Author Report Share Posted February 12, 2015 Thanks Roger, You're spot-on - once we realised, we opened the throttle partially when warming up on the choke, but I would like to get it sorted in a better way. I can't picture my set-up at the moment but I'll get down to the car tomorrow and hunt for Item 55! Norman Quote Link to post Share on other sites
JFerg Posted February 13, 2015 Report Share Posted February 13, 2015 I'd go back to Burlen and simply ask them; they know. Recently I bought a brand new carburettor from them for a pre-war motorcycle. It arrived set perfectly. I bolted it on, the bike started and idled sweetly; idle speed, idle mixture set perfectly. That was no accident. So whilst I've never had cause to ask a question of them, I'm sure that in your circumstance as a customer with an issue, they will know the answer. cheers, JFerg Quote Link to post Share on other sites
TRnorm Posted February 15, 2015 Author Report Share Posted February 15, 2015 I guess I didn't say it was 20 years ago when they did the rebuild but your're right, they should know. But first I think I need to get clear in my head exactly how the choke mechanism on my set-up is working (or not as this case is). So that's today's job. I thought that after 20 years and now on the road it would be plain sailing but I realise this is where the serious fettling begins! Norman Quote Link to post Share on other sites
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