The 'E' Type Forum

I’ve just bought myself a 2nd hand Gunson Gas Tester. I’m going to see if it helps with optimising tuning the Webers. It measures %CO at idle. I’ll easily be able to see a balance between one exhaust pipe and the other, but does anyone know what the actual values for %CO should be?

I’ll be trying it later today, so I’ll report how I get on.

5%

I have used one for years and found it satisfactory. Make sure you warm it electrically for 5 minutes, and then zero it before inserting it in the exhaust. Also, clear everything every 2 minutes or so by running at 2000 rpm for 15 seconds. I aim for 5% CO : bear in mind that you need to alternate between exhaust pipes particularly when adjusting the middle carburetter

I purchased and used a Gastetster a couple of months ago. Dummy me, I still had trouble determining what the middle carb was doing so I added a Colortune. With the Colortune, I could be confident the center carb was close then focus mostly on the front/rear carb to get the Gastester results around 5% as Andrew said.

Gained about 2.5 mpg!

If anyone has a gastester they no longer want then I’m in the market for one.

I have a colour tune too, somewhere. I’ll have to find that and see if that helps with setting up in conjunction with the gas tester. I never had much success with it on its own.

I have a gunson colour tune. Set the car up on it exactly as per instruction, and it didn't run well at all. Trouble is, the E type likes to run richer than the colour tune suggests. So I set it such that it ran with a blue flame on no load, then richened up until it just went yellow. Ran fine then.