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TR2/3/3A very high idle, timing perfect


Senior Member
hi everyone. something to swing by everyone, maybe someone has some guesses.

My TR3a has a really, really high idle. Unfortunately I cannot tell you the RPM's as that gauge is broken (sending it somewhere to be refurb'd after the New Year). But it's definitely running very high.

The timing is perfect. Everyone on this forum helped me with that about a month or so again... it's perfect. I have both carbs sync'd. I believe the gas mixture is right where it needs to be.

Any ideas? If I adjust the timing to bring it "down" a little bit, the car runs like garbage. No power, pinging and ticking everywhere. When i have the timing set perfect, it runs great. But the idle is so high.

One thing I did notice though... the butterflies on each carb. They are synced, but both of the adjustment screws are completely out. If I screw them in even just a little bit, the idle goes through the roof. So I have them both backed all the way out.

Any other adjustment ideas I might be missing? The car runs perfectly. Great power, sounds awesome... super happy about it. Just a very high idle. I feel like I might be missing something, but there's only so much I can think of.

Anyways... thanks a ton for a year's worth of help with my rebuild. No way I would have gotten it done without this forum. Hope everyone has an awesome New Year!


Jedi Trainee
Country flag
Look down the throat of the carbs to make sure the butterflies are closed when the engine is off. If not, you may have to adjust your linkage to make it happen.


Great Pumpkin - R.I.P
I would try disconnecting the linkage at the front carb, first. If that lets it idle down, then you know the linkage is misadjusted or binding. Then try snapping the throttle shut (open it and let it slam shut). If that makes it idle down, you're probably looking at a worn throttle shaft allowing the butterflies to drag against the bottom of the throat. If it still idles high, I'd look for a vacuum leak next. (One way is to spray carb cleaner or WD40 around likely sites. If the engine note changes, you've found a leak.)

If all else fails, someone may not have gotten the throttle plates properly centered to the bore, or installed backwards. If that is the case, you'll have to remove the carbs to fix it (and should replace the throttle plate screws).


Jedi Warrior
Country flag
I second Randall's suggestion of checking the centering of the throttle disc. Also, if the throttle shafts have been replaced, it is possible that the hole for the throttle top was not drilled in the correct spot. This would prevent the throttle disc from completely closing.


Jedi Trainee
You mention the idle adjustment on each carb, but you didn't mention the fast idle screw for the choke. Check it to make sure it's not in too far.


Country flag
It kinda depends on how fast of idle 1200---1500? Do you have a tune up tach on a dwell meter? I usually suspect a vacuum leak like an intake manifold gasket or throttle shafts and yes perhaps the idle screw on the choke is set high. The best timing is set by driving and I find that the timing is usually a little advanced, so for me when I turn the timing back the engines does bog down. I find a balance between the timing marks and a good idle. Too much dwell will make the engine idle a little fast also. In my experience if you can get an idle of 800, you are doing well.


Freshman Member
Country flag
Good suggestions so far.... I was having a similar problem and finally solved it by adjusting the float valve on one of the carbs.
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