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2 inch SUs choke?

Posted: Thu Mar 10, 2016 11:40 pm
by tom16v
I have a pair of HS8 carbs that I was planning to fit to my Sprint when I fit the rebuilt engine. I think they are from a Jag and would have had some kind of auto choke mechanism separate from the carbs, as there is no provision for a manual choke mechanism.

Those that have fitted these carbs... How have you overcome this issue?

Any pictures would be great please! :D

Thanks in advance

Tom.

Re: 2 inch SUs choke?

Posted: Fri Mar 11, 2016 3:50 am
by gmsclassics
viewtopic.php?f=4&t=19042

I was faced with the same issue some years back, but never got past running with the choke only operating on the rear carb. That did enable me to start the car, but it did run very lumpy until warm. Okay for a track car but too annoying for a car to be used on the road.

I ended up switching to standard carbs and converting the car to auto, but I did get a response by email with photos from someone who had made the relevant parts needed and he supplied photos and a diagram. If you pm me your email I'll happily forward that on to you.

Geoff

Re: 2 inch SUs choke?

Posted: Fri Mar 11, 2016 8:07 pm
by GrahamFountain
You can, or at least could, get all the bits from Burlen Fuels. I've had a set of HS8s I've been considering using and which have been hanging around several sheds for at least 15 year. They're a bit mucky now. They were originally intended for a TR7 Sprint, and I understand they'll fit without fouling the bonnet. I believe they'd need the dashpot shortening on the front one on a Doly, or a bit of a bulge in the bonnet.

At the time, I could only get the throttle lever plate that takes the screw to increase idle speed for one end, the back carb. So, while that will lift the throttle on both carbs, it'll lift the idle on the back carb more than the front, because of the slack in the throttle spindle mechanism.

Here's a picture of the lever plates without the screw that follow the cam on the choke lever plate and without any of the external springs (need a pair of needles too).

Image

The choke cable connection is on the front carb, and operates the rear through a choke spindle. As I remember, there's no reason it couldn't go on the back one instead.

It's also possible that Burlen now have the mirror image of the throttle lever plate for the front carb, as the front choke one has the cam on it. That would mean you could adjust the idle increase on the two carbs separately.

Graham

Re: 2 inch SUs choke?

Posted: Fri Mar 11, 2016 8:20 pm
by GrahamFountain
Went and had a trawl about the throttle plate for the front carb, and there're front and back carb ones in this kit http://www.scparts.co.uk/sc_en/manual-c ... 50938.html.

Bit expensive I thought, though.

Graham

Re: 2 inch SUs choke?

Posted: Fri Mar 11, 2016 11:38 pm
by tom16v
Thanks very much for the info chaps.

I think all I will need is one set of the throttle and choke levers. I think I will contact SC parts and see whether they will sell me these parts separately once I have gone through everything else carefully to make sure all is well.

Cheers

Tom.

Re: 2 inch SUs choke?

Posted: Sat Mar 12, 2016 10:19 am
by GrahamFountain
Tom, If you get a price on a front carb throttle plate lever that is threaded for the choke-cam follower screw, please would you let us know.

Graham