Using colour tune ?

[arriva1]

Have Weber twin choke setup and just fitted pcv system but require to adjust mixture correctly ?
At first after fitting pcv car was cutting out while driving but as per instructions with kit said that mixture would need adjusting.
Did this in 1/4 turns and finally got car to run and sounds very well again but can't be sure mixture is correct ?
Am aware of " colourtune " but adjusting with this what spark plug do I take out on each side for adjustment ?
Trev

[arriva1]

this is current photo with pcv kit installed : DSCN1612.jpg

[jleyton]

To use colourtune you only need to check one cylinder per carb.

On the Stag each carb feeds the middle two cylinders on one side and the front and rear on the opposite sides so you can use the colourtune in, for example, cylinders 1 & 2 or 3 & 4 etc.

Cheers

Julian

[arriva1]

Julian,
so only need to use the one cylinder on either side ie 7 on one side and 8 on other ? ignore all others ?

Trev

[Hettiherald]

the webber set up is of a fixed jet design, the only adjustment you can make is for the tickover setting.
If you need to adjust the mixture for running speeds, you have to change the jets. As long as the car ticks over ok, there should be no need for any further adjustment.
Dave

[RNF]

Julian Trev has the "Weber Twin Choke" not the Strombergs. The setup you have the manifold will feed equally each bank. Just install the colortune in the #1 cyl (doesn't matter really).

The Stromberg twin carb setup (stock setup) one carb feeds 4 cyl's (#1, 2, 7, 8) and the other carb feeds 4 cyl's (3, 4, 5, 6). You can follow the runners. Anyways, it's a non-issue with the Weber

[arriva1]

says with weber active breather kit instructions after fitment : Important note : due to additional air flow the idle mixture will normally need to be enriched.
Before I done that car kept cutting out.
Trev

[jakesmig]

As Dave says, the weber is a fixed jet, so if you need to check the settings it is best done on a rolling road then a set of jets can be matched to the needs. It's a black art needing knowledge of fuel and air jets.

Set your desired tickover rpm then use the colourtune to set the mixture for that setting. If you later reduce the revs you will need to enrich the mixture slightly, conversely if you raise the revs you lean the mixture slightly, sounds odd but at low revs, therefore low air flow, the fuel doesn't atomise efficiently therefore needs enriched to compensate.

John.

[flying farmer]

I have always found on carb idle mixture settings (at least for the Holley I had fitted) that the easiest way to set up the idle is to enrich the mixture to the fastest tickover speed. This will be the maximum power mixture which will be too high for MOT purposes, so then you weaken the mixture again until the idle speed shows the first signs of dropping, then turn it back towards rich just a fraction.

This should give a steady idle and good emissions.

This actually works for the idle mixture on my old style flap type efi system too!

Neil

[jleyton]

Doh - totally missed the 'Weber' - sorry

Cheers

Julian

[KOY 23]

Julian.
You are right. The Weber sold on this forum uses the standard manifold and an adaptor plate into which the 2 chokes feed into the seperate halves of the manifold, just like the Strommies. There are only 3 adjustments; idle speed and mixture for each choke.
No doubt the supplier has checked the mixture fully across the range to ensure jetting is correct with PCV valve.

[Staggard]

Julian.
You are right. The Weber sold on this forum uses the standard manifold and an adaptor plate into which the 2 chokes feed into the seperate halves of the manifold, just like the Strommies. There are only 3 adjustments; idle speed and mixture for each choke.
No doubt the supplier has checked the mixture fully across the range to ensure jetting is correct with PCV valve.

That's the way I see it as well. My only question is John is that a Politically Correct Valve

[arriva1]

As mentioned have adjusted mixture on both sides with Weber after fitting pcv ( as was stalling while trying to run car, was fine at idle ) and car sounds great and runs super great now but just wish to know if mixture can be checked and adjusted with colourtune or just take car to MOT station and see what emissions are like ( what should emissions be ? ) , other is to check plug conditions I guess ?
Trev

DSCN1612.jpg

[jakesmig]

As far as I know, emission tests on cars to mid 70's is purely visual, if it smokes too much it fails

[milothedog]

As far as I know, emission tests on cars to mid 70's is purely visual, if it smokes too much it fails

Up until Aug 75 IIRC