Engine Tune (1) 09/07/04
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There are two parts to general engine tuning. These being air fuel mixture and balance. Its best and easier to do both at the same time using some simple and relativley in expensive tools. These being a carb balance which I suggest the Morgon CarbTune II and a 14mm ColorTune. The CarbTune allows you to check the vacuum of all carbs while engine is running to ensure equal air/fuel amounts are drawn into the cylinders. The ColorTune is essentailly a spark plug with a clear top to allow you to see the colour of the detonation within the cylinder. Both of these were obtained from www.carbtune.com.

I need to document this much better with more pics

Using ColorTune to set mixture
Yellow = Rich
Blue = Perfect
White = Weak

Go for a drive as normal to get the engine to tempertature.
Fit ColorTune in place of spark plug.
Ensure tickover is around 900 rpm, If not adjust the idle screw
Start her up and look at/adjust the colour on tickover (Should be blue but the Lotus Turbo engine its better to have a slight gold tinge). You may need to idle to ensure 900rpm is kept.
Slowly raise the rev's to 2k and check/adjust again (Should be blue).
Again increase to 3k (Blue) and back down.
Finally Increase revs rapidly and release. (This should add a gold hint and then change to blue).

Using CarbTune to syncronise carbs
Ensure Engine at temperature.
Close but do not grunge all air bleed screws.
Remove vacuum test screws and fit CarbTune. One guage per carb barrel.
Start her up and look at the level. You are aiming to have them all level.
Start on one carb (2 barrels) and using the bleed screw or the higher barrel open it until the pair are level. Note the actual value or the other two levels are not important.
Move to the second carb and again using the bleed screw for the higher of its pair adjust until both are level. Althogh again not necessary the value as the first pair.
Adjust the connecting bar (near throttle cable) so both pairs are now level.

A view of the carb showning the points you need to adjust.

Yellow = Fuel/Mixture. (One per barrel)
Red = Vacuum test. (One per barrel)
Blue = Bleed screw. (One per barrel)
Green = Idle screw. (Only One)
I removed my rear plug to check condidtion. This does have a slight build up of white deposites and shows signs of running a bit weak. The black is caused by running with the choke on while stationary.
I had some oil down in the plug hole but could not find any sign of its source so put it down to spillage when topping up the oil.
ColourTune Fitted in place of spark plug.

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