2 replies to this topic

[Deceptacon]

Hey,I have twin HS2's running on my 1990 BRG and they are totally out of wack. The car dies at idle without any revs, yet misfires and hesitates under acceleration. Dashpots fully topped up, and new points, condensor etc. on their way to me.

Basically, I want to get the mixture setup somewaht better than it currently is, and I'm going to use colourtune. Obviously, with a single carb, it is quite an easy process, but it has never bin covered for twin carbs. I read somewhere that you would need two colourtune plugs(I think it was on here?) but no instructions followed.Any idea guys?

After this I will hopefully purchase a timing gun and get the timing better as well as valve clearances.If yu're wondering, there are no rolling roads where I am!

Cheers

[minidaves]

yes can be done with two colour tunes, or just one infact, basically start from scratch set the twin carbs up with jets in same place and throtle linkages working together with idles set the same, and work through it adjusting each bit at a time

takes me about 1hr but then they are sweet

dave

[Dan]

but no instructions followed.Any idea guys?

Well oddly enough the instructions come with the Colour Tune, repeating them here seems a little pointless. For twin carbs, fit one Colour Tune plug to a cylinder fed by each carb and tune as normal, tuning both carbs a bit at a time so it never gets very far out of balance as Dave says above. I'm sure this is covered in the instructions too but It's been a long while since I saw one now.
Tuning with one Colour Tune will be trickier but as Dave also says is possible. You have to do the majority of tuning to the first carb, assuming the two to be similar and making the same amount of adjustment to each having first used a vernier to check the jet heights of each are matched and that all the linkages are correctly balanced. Then start checking each against each other once they are roughly tuned, you will have to stop and start the engine several times at this point. Swapping the plug over and doing a bit to each carb at a time. If you try to fully tune one carb at a time it will go wrong as the tuning of that one won't be right anyway and the engine will be running badly unbalanced which is not good for it. That's why it's easier with two plugs.