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There was a previous thread on a 3 that had a high idle and was running rich. I wonder if that person ever tracked down the problem? I have a 3 with a mild street cam and header....runs fine except for a high idle(around 1200 rpm). I've opened the valve gap up to .016(they were at the stock .010) and that seems to have helped. The SU's are set up pretty good and performance is fine...except for the sooty plugs which would indcate a rich condition. Without mucking about too much with the carbs could I just lean out the mixture one or two flats to see if I can get the light tan plug colour that I should have? Any suggestions? Karl
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TR2/3/3A TR3..Black sooty plugs?
- Thread starter karls59tr
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PeterK
Yoda
Offline
Yes. Just put a dab of paint on one flat on each carb (for reference) then turn in (clockwise looking up or anti from the top) a couple of flats. Blow off the plugs with brake cleaner and compressed air, then retest.
Plugs 1 and 2 for the front carb and 3 and 4 the rear carb.
ColourTune is great (so I'm told) but I've never needed one to get that turkey turn brown color from a good running carb setup.
Also check the normal stuff like choke on, etc.
Ignition must be spot on and engine must be up to temp to tune also.
Plugs 1 and 2 for the front carb and 3 and 4 the rear carb.
ColourTune is great (so I'm told) but I've never needed one to get that turkey turn brown color from a good running carb setup.
Also check the normal stuff like choke on, etc.
Ignition must be spot on and engine must be up to temp to tune also.
prb51
Luke Skywalker
Offline
I do a plug check on a hot run without idle by finding a long clear road and run it at speed then cut the ignition, coast and pull off and check the plugs.
You may be rich at idle and ok/lean at speed.
I'd like to get a color tune myself and suspect that's a good tool to use.
You may be rich at idle and ok/lean at speed.
I'd like to get a color tune myself and suspect that's a good tool to use.
TR3driver
Great Pumpkin - R.I.P
Offline
IMO plug cuts are much more accurate than a Colortune, because the plug cuts reflect the mixture under load & speed rather than at idle. Especially with a hot cam, the idle mixture may go way rich while leaving the cruise/power mixture too lean.
I fought overheating problems for several years on a TR3A, that turned out to idle rich (because of worn jets). When I set the idle mixture, it forced the cruise mixture so lean that the engine would overheat (as well as be down on power).
Note that when reading plugs, it's important to look at the tip near the electrode. Since our gasoline is no longer leaded, the shell may stay black for a long time after a single episode of too much choke. (Leaded fuel used to leave a lot of white lead oxide on the plugs & tailpipe, but unleaded leaves much less deposit & it's not white.)
Besides, "lift the piston" is just as accurate as a Colortune, and doesn't require all that mucking about to use.
I fought overheating problems for several years on a TR3A, that turned out to idle rich (because of worn jets). When I set the idle mixture, it forced the cruise mixture so lean that the engine would overheat (as well as be down on power).
Note that when reading plugs, it's important to look at the tip near the electrode. Since our gasoline is no longer leaded, the shell may stay black for a long time after a single episode of too much choke. (Leaded fuel used to leave a lot of white lead oxide on the plugs & tailpipe, but unleaded leaves much less deposit & it's not white.)
Besides, "lift the piston" is just as accurate as a Colortune, and doesn't require all that mucking about to use.
PeterK
Yoda
Offline
You have to own or borrow a ColourTune to use it and that means you have to order it and wait for it to
arrive on your doorstep.
By that time, I'd have it dialed in and already been on a few drives. I'm sure that the tool is good but when you don't have one, I try it the "old" way, usually works too.
arrive on your doorstep.
By that time, I'd have it dialed in and already been on a few drives. I'm sure that the tool is good but when you don't have one, I try it the "old" way, usually works too.
