Aribert, Bob,
I can add a futher thought as to why you would not want to go down the path
of direct "header" output! If you are going to go to the trouble of making
holes in the header, you might as well fit an O2 sensor: this has the
distinct advantage of giving exact fuel/air ratio so you can dispense with
the Colortune altogether (although it is still a useful check of "which"
cylinder is not firing consistently every cycle).
There a number of good articles in the archives on O2 sensor fitting, and I
know that number of listers swear by them, since they are always "on" so
you can monitor the mixture under all road/throttle conditions.
The only thing that has put me off so far is the fact that I have a double
downpipe so I would need to fit 2 sensors, and I have a SS system, so would
need a welder able to weld, with more skill than me (not hard to find), the
sensor boss on SS pipe (more difficult!). I also read recently a message
from an MG owner (sorry ...) that mentioned that if the sensor is more than
8-12" from the cylinder head, that a 3-wire sensor would be needed ... the
heating effect from the burnt gases (needed to get accurate readings) might
not be sufficient at idle. Can't confirm but sounds sort of logical.
In the meantime, I use my Colortune which, used in conjunction with a
cheap-but-cheerful Gunson carb airflow meter, is as good as it gets until
you get up to CO2 meters. And any listers going down the Colortune path:
see if you can find someone visiting the UK to pick up one up for you - get
them to pick up both these items at 1/3 the cost of the big 3 at Halfords
(a national autoparts chain in the UK).
Tony Gordon
>>I have been told that if one looks at the exhaust flame immediately
after the
>>head one can use the flame color same as using the color tune system. I am
>>considering drilling small inspection/tuning holes in my headers and brazing
>>nuts over the holes so that I can plug the inspection holes with short bolts
>>when not in use. Will this work, what thinks the list?
>
>Two thoughts on the exhaust inspection ports:
> A. The flames you are hoping to see will reveal themselves with
>considerable gusto, and may present a noise and fire hazard within the
>engine compartment. Watch those eyebrows!
> B. opening up the ex. header will probably change the flow
>dynamics, ( ie reduced backpressure, no scavenging, etc.) and render you
>carb adjustments 'inaccurate' when the holes are plugged up again.
>
> If you want to get fancy, maybe installing a thermocouple in each
>ex. manifold port would reveal some useful info. You could measure the
>temps, and adjust the carbs- at least getting them to match-- however
>exactly what the correct temp is may have to be experimentally derived.
> regards,
>B Westerdale
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