Dashpot Oil Question
Total posts: 1368
Last post: Jul 20, 2023 Member since:Jul 15, 2008
|
Cars in Garage: 0
Photos: 117 WorkBench Posts: 1 |
|
Total posts: 4134
Last post: Oct 13, 2020 Member since:Oct 8, 2011
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
|
Total posts: 1368
Last post: Jul 20, 2023 Member since:Jul 15, 2008
|
Cars in Garage: 0
Photos: 117 WorkBench Posts: 1 |
|
Total posts: 7048
Last post: Jan 29, 2024 Member since:May 23, 2002
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
|
"Retired: No Job, No Money, Wife and I! Will travel anywhere for Minis"
Total posts: 1368
Last post: Jul 20, 2023 Member since:Jul 15, 2008
|
Cars in Garage: 0
Photos: 117 WorkBench Posts: 1 |
|
Total posts: 3862
Last post: Dec 2, 2019 Member since:Apr 26, 2005
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
|
Total posts: 1368
Last post: Jul 20, 2023 Member since:Jul 15, 2008
|
Cars in Garage: 0
Photos: 117 WorkBench Posts: 1 |
|
Years ago when I bought my first GPS unit I changed the default voice from "American Guy" to "British Gal." Although some of her terms were a little hard to interpret; parkway for highway, throughway for boulevard, etc., I found her voice charming... until I rented a car in Washington DC and she said "You are about to enter a roundabout. Please enter in a counter-cyclonic direction." Wait, what?! That was the end of British Gal.
Total posts: 1368
Last post: Jul 20, 2023 Member since:Jul 15, 2008
|
Cars in Garage: 0
Photos: 117 WorkBench Posts: 1 |
|
Total posts: 9528
Last post: Mar 27, 2024 Member since:Aug 14, 2002
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
|
.
"Hang on a minute lads....I've got a great idea."
Total posts: 834
Last post: Mar 7, 2023 Member since:Aug 15, 2002
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
|
Total posts: 1368
Last post: Jul 20, 2023 Member since:Jul 15, 2008
|
Cars in Garage: 0
Photos: 117 WorkBench Posts: 1 |
|
I was pretty systematic. Not my usual MO. As a result I think I have it narrowed down—at least as best I can w/o a dyno.
Dashpot oil: thinner viscosity allows it to rise faster, allowing more air and less fuel during acceleration (leans it out). Thicker does the opposite.
That's what I was looking for. I'll start with slightly thicker oil as the initial hesitation seems to me to be a slightly over-rich condition. Not going to mess with a different needle. The needles were selected by my engine builder as were the settings on my 123 dizzy. Gonna leave well enough alone. This flat spot I'm experiencing is really rather minor. Thanks for everyone's help. Will advise.
Total posts: 3749
Last post: Mar 26, 2024 Member since:Jun 23, 2000
|
Cars in Garage: 1
Photos: 201 WorkBench Posts: 0 |
|
I admit it is a lot easier looking at a lambda reading when adjusting the idle setting. My current issue is that with distributor less ignition, my idle is hunting slightly which makes the lift pin check method non-functional.
Although today in the 105 F heat, there was little hunting at the stop signs.
Terry
Total posts: 10232
Last post: Mar 26, 2024 Member since:Mar 24, 1999
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
|
Total posts: 3749
Last post: Mar 26, 2024 Member since:Jun 23, 2000
|
Cars in Garage: 1
Photos: 201 WorkBench Posts: 0 |
|
What change would be expected in lambda when lifting?
Terry
Total posts: 8382
Last post: Jan 13, 2022 Member since:Feb 7, 2006
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
|
If you think your needle may be on the weak side to test it loosen up the needle and move it up into the piston slightly so the needle will be running slightly richer then take a look at needle charts mintylamb.co.uk is a decent one to use.
You could also test it with the choke slightly out to see if that improves things.
If you have the newer swinging needles they self center.
As pointed out by Alex and Norm you may need to get a wide band sensor or a session on a rolling road.
If in doubt, flat out. Colin Mc Rae MBE 1968-2007.
Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.
Total posts: 654
Last post: Dec 20, 2017 Member since:Sep 24, 2011
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
|
Dashpot oil: thinner viscosity allows it to rise faster, allowing more air and less fuel during acceleration (leans it out). Thicker does the opposite.
Needle tuning: the needle has 1/8" increments of diameter change, allowing you to fine tune WHERE in the throttle stroke you richen or lean the mixture.
Ignition timing: adjusting the mechanical advance by spring strength or by weight shape moves the spark advance up or down the rpm range, helping the engine use the fuel it gets most efficiently.
N
Total posts: 10232
Last post: Mar 26, 2024 Member since:Mar 24, 1999
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
|
Total posts: 1368
Last post: Jul 20, 2023 Member since:Jul 15, 2008
|
Cars in Garage: 0
Photos: 117 WorkBench Posts: 1 |
|
I’ve synced and adjusted my twin SUs and I think I’ve finally got them dialed in. The motor idles well, pulls strong and the plugs look great. There’s just… one… little… thing. I’m getting a slight hesitation—a flat spot, so to speak, right at the bottom of each shift under light throttle pressure. Most people unfamiliar with my car probably wouldn’t even notice. The hesitation lasts only a split second and doesn’t occur at all under hard acceleration. Perhaps I’m noticing now only because the carbs are truly in tune, mixture-wise.
Seems to me I read somewhere that this kind of flat spot is most likely related to the dashpot oil. I can’t recall if I should try increasing or decreasing the viscosity. Which is it? Thanks!