Dieseling after shutoff...

[TedW]

My engine has begun to diesel after shutoff, usually for one to five seconds.

Is this doing any damage?

What can be done to stop it?

The engine is new - 3,000 miles on it, with a new Ducellier distributor and a recently installed Pertronix electronic ignition. Everything is super-smooth (other than the dieseling). I run premium fuel.

Thanks in advance for your opinions and advice.

Ted

[yorker]

Double check your timing & your carb, are you using e10?

see here:
http://mgaguru.com/mgtech/engine/ro101.htm

[TedW]

BTW - It's a Weber carb.

[yorker]

How is the weber jetted? Out of the box many of them are jetted lean.
http://en.wikipedia.org/wiki/Dieseling

E10:http://en.wikipedia.org/wiki/E10_fuel

Most gas around here is E10 now since the other oxygenated fuels lthat used MTBE have been banned. Alcohol in your fuel could be contributing to the run on.

[TedW]

My mechanic (outstanding, by the way) explained the jet problem to me after he installed the carb.

Thanks for the Wiki links - very helpful.

Should I try 89 octane instead of 93 to see what happens?

[yorker]

What is your engine's compression?

If you can find fuel without alcohol then give it a try. Alter your timing and check your idle speed.

[Les Parker]

We've had good success with the fuel shut-off solenoid, RNF390. :-

http://www.roversnorth.com/store/searchadv.aspx?SearchTerm=RNH390&Issubmit=True (http://www.roversnorth.com/forums/../store/searchadv.aspx?SearchTerm=RNH390&Issubmit=True)

[TedW]

Compression is strong as the engine is new (not rebuilt or remanufactured). I don't know the #s off the top of my head.

[yorker]

Well I mean is it an 8:1 or 7:1 or have you bumped the compression by shaving the head or something? These engines were designed to practically burn kerosene originally and don't really require premium fuel.

[TedW]

Nothing special with the head except for a 2.5 cam.

[Jim-ME]

I'd think that you'd be better off to run 87 octane and set the timing accordingly. I can't believe that a Rover needs premium fuel.
Jim

[TedW]

However I could be reading the numbers wrong.