No. Dieseling is when the engine continues running for a few seconds after the key is turned off. That is usually caused by lean mixture and/or incorrect ignition timing causing hot running. Drive any car from the early '70s…
Regards,
Ray L.
forgive my ignorance, what’s overrun?
Coasting down from high RPM in gear, throttles closed.
Regards,
Ray L.
So, not experiencing normal engine braking.
I have three Colortunes, used simultaneously. For optimum results you do need to do a little seat-of-the-pants fine tuning after setup as Ray says, but I’ve found they do a decent job of getting the mixtures close.
We got into this discussion back in ‘14. The conversation got to be a little more animated when the reference to Colortune in the manual pictured came up.
Essentially, the author recommended jacking up the rear wheels and having an accomplice simultaneously apply the throttle and the brakes (in gear, of course) whIle you fiddle with the mixture. 
What could possibly go wrong there? 
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Good word choice… ‘assistant’ wouldn’t quite cover it.
Choose carefully – someone who is a beneficiary on your whole life policy may be less than ideal.
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Roger- do you have a triple SU or dual ZS carb setup? On my dual ZS setup I’ve installed adjustable jets in the carbs and lambda sensors in each of the exhaust downpipes. Since there is a 1:1 correlation between carb and exhaust pipe I can tune each carb at idle and then monitor the air/fuel mixture during driving to see what fine tuning would be beneficial. I’ve yet to fire it up but theoretically it should work like a champ.
I think subsequent editions to the manual omitted such sage advice, perhaps after a mishap or two?
I should mention that optimising the mixtures across all three carbs with the Colortunes took some fiddling before replacing the carbs with a rebuilt set with new spindles, bushings and butterflies. If you have any air leakage at all you end up chasing your tail, but that goes for any approach you take.
I have a copy of the book the recommends the ColourTune, the helper, and the brakes. I never read that part of it before. They suggest checking mixture at 2000, 3000, and 4000 RPM, under load! You could not pay me to do that. Imagine what that does to the life of the rear brakes…
Regards,
Ray L.
Have the SU setup. Mallory dual point distributor
Set timing to 28 degrees advance . engine has headers and hotter cams. While setting up the carbs I set the carb air flow with a hose
Set the mixture by lifting the pistons
Keep checking the tailpipe sound and within 4 adjustments hit a perfect even exhaust note.
That just sounded perfect. Drove the car and it couldn’t run sweeter. Gas millage seems much better. And when backing up no smell from the exhaust. Not going to use the color tune
Because it runs to nice as is.
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If it aint broke… Sounds like you’ve got it running nicely!
I also am about to get around to setting my SU carbs - the car seems to run well, strong, no pinging in limited drives up hills, etc. But I was always wondering about the strong exhaust smell (even after warmup), which I attributed to no emissions controls.
If Roger’s experience holds true in my case, then proper tuning may reduce or perhaps even eliminate the strong exhaust odor. One reason I dragged my feet on carb adjustment is that I don’t want to mess with something if it works fine, but if pungent exhaust is a sign things aren’t that good, then I have no hesitation to dive in and try to improve things…
Dave
Doug, How do you read the LAMBDA sensors and how do you monitor them while driving?
The sensor lines go through an unused hole in the firewall and the readout can be temporarily installed anywhere below the dash or really anywhere you can see it. 12 Vdc from your favorite switched fuse with some available current.
Results that I got were worth the effort.
I first set the points and then timed the engine.
Then followed the Bentley manual to the T.
Make sure you disconnect the enriching levers.
Using the hose to listen to the hiss in the carbs worked a treat. Ill never use the uni syn again
All has to be working correctly in order to adjust the carbs as the manual states.
Just took the car for a 25 mile run and it ran joyously. Idles at 500 rpm. And runs cool.
Worth the effort
I would believe that a lot of carb issues are caused by the enriching levers not being adjusted correctly. Becuse they are hard to get at. My engine now starts immediately and idles at 1000 rpm with the dash board chock lever half out
Never did that before.
I thought the saying was that " You can’t be too rich or too lean"
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Doug
The Innovate system when used with adjustable jets works great. As Ray points out you set it when under load. I set mine by driving it up a long up hill grade and watching #s. My fear is always that it is running too lean, and in the process destroyed a few O2 sensors from running too rich.
Glenn