TR2/3/3A SUs Running Rich

[NutmegCT]

Glad you're finding some success.

Say, didn't you write in the first post that turning in the adjuster a couple of flats didn't change the performance?

I don't understand why your 750rpm idle changed to 1200.

Hopefully you did check that the pistons drop smoothly, verifying the needles are centered.

Keep us posted!
Tom M.

 

[Roys]

leaning out the mixture(to a point) raises the idle

 

[NutmegCT]

Thanks Roy. Didn't realize it would almost double the idle speed.

 

[karls59tr]

While we are on the subject. In spark plug terminology.... the last time I did plug checks the insulator tips,center electrodes,ground electrodes and threads were the light tan color that is supposed to indicate everything is firing as it should. Curiously the gasket and seats have black,fluffy carbon deposits. Wonder what would cause that not that it appears to be problem?

 

[frankfast]

Thanks Roy. Didn't realize it would almost double the idle speed.

The car was previously idling at 800 RPM so turning the mixture screw raised it 400RPM.

To answer a previous question, a 1/2 turn of the mixture screw is more than turning a couple of flats and apparently made a difference. It probably can go a bit more.

Also my first plug checks involved a bit of idling whereas the last plug checks I tried to avoid idling as much as possible.

I still believe that these carbs are rich at idle even when they are dialed in correctly.

 

[TR3driver]

They are supposed to idle just a smidgen rich, something like 5% CO IIRC. But not enough to cause any symptoms visible without a CO meter (like rough idle or smoke in exhaust).

If you can't get them that lean, or if leaning out the idle makes the cruise mixture go too lean; then you've most likely got worn jets and/or needles. Could be other things, like a leaking upper gland or a float valve that doesn't close fully. I think we've already mentioned not having the jet return against the mixture nut after releasing the choke, too.