Twin Carburettors HS8 - mixture won't adjust

6

692000tc

New Member
As I'm about to become a member of P6ROC, I'm taking the liberty to post a question.
I have a 69 2000 TC, with HS8 carburettors (I believe). Some time ago I bought Gunsons colortune, and it works very well. My problem is that my front carburettor won't produce the blue flame that I want to see. The rear carb is working ok. Guess they need an overhaul, but what is wrong, from a technical view?
And, by the way, how can I use the gunson carbalancer. The pins to the air filter box is making it impossible to get an airtight connection.
Maybe som bad english here, but hey, I usually write Norwegian..............

Rgds Petter
 
With the carb balancer you have two simple options - either file a groove in one edge of the outer plastic disk- just enough to clear the filter mounting stud (if you are careful this will not affect the function at all) or if you prefer make a ring of plasticine around the carb intakes and press the balancer against that, slightly offset to avoid the stud.

Make sure that the crankcase and rocker cover breather pipes are sound and the flame trap is clean - these make a difference , as does the vacuum pipe to the servo and the advance return pipe and its elbows.

Check to see that the choke cable is free and that both mixture levers return to touch the stop screws when the choke is pushed fully in. Try moving the mixture levers by hand , is the jet moving up & down freely seen/felt under the carb - if it sticks WD40 and manual movement up & down "may" free it.

Balancing these carbs in my experience is a long slow fiddly and frustrating job - which can be done by an amateur - but eliminate everything else that might affect the carburation before you start twiddling those screws.... it doesnt take much error to end up with an undriveable car.
 
Hello Petter,
Your English is a zillion times better than my Norwegian!
Do you have a workshop manual? The Haynes manual says you need a piece of rubber tubing 2" diameter and 1 and 1/8" long to clear the studs (they use a Crypton "Synchrotech" device for balancing but a Gunsons carbalancer will do the job)
I like bullroarer's idea of plastercine! - Guess bluetack would do the same job. Alternatively use a piece of windscreen washer tubing to listen to the intake roar and balance the carbs by sound - It's easier than you think and very accurate!
I guess that the colourtune is showing a rich mixture (orange flame) on the front carb' which could be caused by a number of things, including leaking float chamber needle valve, damaged float, incorrect float adjustment, sticking or out-of-adjustment choke linkage, general needle/jet wear.
Hope that some of this helps.
Regards, John.
 
Is'nt it wonderful when the hints you get solves your problem? My problem with the front carb was caused by a sticking jet under my front carb. So after some adjustment i've managed to get the right mixture on both carburetters.

Petter :)
 
Carb balancer with little red floating balls:
I selected a microwavable bowl of the same internal diameter as an air filter. I drilled and used a jigsaw to cut a hole in the bottom as big as I could without the balance falling through. I used contact cement to glue the balanceer to the bottom of the bowl. Now, the balancer just slaps on each carb in an airtight fashion.

Another useful tool is the Gunson's CO Meter. I bought one as we have an annual emission control test. For the past 2 years I have been recording data so that now I know the CO reading to pass the test. The accuracy is great. Just by changing the needles from AAB to AAM I was able to reduce the CO output on the meter.

I also have a Colourtune and used it initially tgo set the carbs. The CO Meter is used for a quicker preparation before the test.

Eric
:)
 
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