HS8 choke.

S

Steve C

Member
Just purchased a p6 2000tc and am having trouble with the choke, must stress i am very new to the HS8 tc set up, but the car will not start with the use of the choke at all, when i manage to get it running with out choke, it will run quite smoothly, however if i just touch the choke the engine just dies straight away??
I have removed the top of the carbs and looked in side, when the choke is pulled the jets do move down and back up when control is pushed back in.

not really sure what is going on, and advice would be great

Regards Steve
 
The HS8 carbs are quite difficult to tune. The chokes can be really awkward.

First I’d make sure they’re setup as per the manual. Make sure that the fast idle cam is moving the butterflies when the cable is pulled. Easiest if you have a friend pull the choke while you have your head stick under the bonnet. Also, make sure that the jets return to position under the carbs when the choke is pushed back in.

If those are doing what they should I’d check the carbs for wear in the spindles. with the car idling spray a little brake cleaner or easy start around where the butterfly spindles enter the carb bodies. If the idle speed changes chances are the spindles and spindle bushes are worn. If they are it’s almost impossible to get them tuned properly and should have the spindles and bushes replaced.
 
Thanks for the super quick response Ive just sold the v8 and had the carbs on that set up great, but as i said these just look so different, and trying to understand the manual, goes right over my head.

i have noted the first line of your post (the chokes can be really awkward)

pretty sure i have the mixture about correct, and it idles ok, as you suggest ive sprayed brake cleaner around the spindles and there is no change to the idle, once warmed up she drives very well, just the choke that i cant work out.

regards Steve.
 
Hey Steve,

So, with the chokes. The HS8's fitted to the TC are unique to both the TC and certain Jaguars. The difference being that they have a mixture adjustment screw next to the idle screw instead of the normal nut below the jet for other SUs. This means the choke mechanism also moves the jet via the same mechanism. The fast idle is adjusted by a screw that mates against the cam of the choke lever. You want a gap between the cam and the screw when the choke is pushed fully in. When the choke is just pulled out you should get the cams moving the screw and increasing idle. Speed should be around 1200 RPM. Then, as you pull the choke further out you should see both jets drop below the carbs (you may need a mirror or remove the air cleaner to see this.
Hope that helps.
 
Many thanks once again, with your help and advise I think I have found the problem, when i pull the choke out the jets do drop as they should, however i have now noticed that there are no fast idle screws fitted at all !!!!! as you know they are fitted on the side upside down, thus when the cam is moving nothing is bearing on it to increase the idle speed, thus the engine just stalls !! how the previous owner managed to run the car like that i will never know,
next problem is to try and find suitable screws.
Regards Steve.
 
Burlen Fuel Systems will be your friend, but call them rather than trying to identify the parts you need from the website. A choke return spring was missing from one of the HS8s on my TC, and it doesn't appear on the website's exploded parts diagram. However, Burlen were able to find the right part once I'd emailed them a pic of it from the factory P6 manual. When set up properly and not worn, the HS8s work very well and I love their ludicrous enormity.
 
Once again many thanks for the above advice, choke works well now, however trying to tune the carbs has not been straight forward,

i could get them set up and all seemed ok, then the car would start sounding like a tractor, with the exhaust spiting and back firing and generally running rough, no end of tweeking would sort it out,

now took the bell chambers off again and tried to reset them up, and noticed that the jet in the front carb was not returning correctly, ( every couple of times it would stick down), no wonder it sounded like a tractor.

I know this is not the correct action to carry out, but Ive now sprayed carb cleaner down the jet to no effect, and then in desperation sprayed wd 40 down the jet, working it up and down at the same time, and now it seems to be moving nice and free, not had time to re assemble and try, but time will tell

Regards Steve.
 
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