Motor Diesels

[novaracer1]

Hi all,

Why does my motor diesel badly sometimes and sometimes it doesn't? Just got back from a nice cruise and shut the car off and holy crap, smoke coming out of the carbs like crazy as it's dieseling. Other then that it runs pretty good.

Thanks

[Nova_Power4]

combustion chambers red hot??
knocky fuel and highcompression???
worst l'v ever seen was a GTO deisleing itself to death every time lasted good 30seconds even had the coil unpluged never did figure it out tho

[novaracer1]

combustion chambers red hot??
knocky fuel and highcompression???
worst l'v ever seen was a GTO deisleing itself to death every time lasted good 30seconds even had the coil unpluged never did figure it out tho

The little tiny bit of fuel that was in there from last summer was ran almost out and I put fresh in.Compression is about 11.5:1
Combustion chambers? I don't think they are hot. the car ran at 180* all day today. Don't really know if that has anything to do with that, but none the less, should I go to a colder spark plug?

The thing that sucks is that it doesn't do it all the time.

And, of course, it only happens when another car guy is watching.:rolleyes::rolleyes:

[Nova_Power4]

how bad is it>?>?
like a 2-3second blamp blamp blummmmm
or knock thud knock thud knock thud thud vroumph

my 403sbc did it on occasion but it was because it was heated right up after beating on it about 220F itd be a 2-3second run on

[novaracer1]

how bad is it>?>?
like a 2-3second blamp blamp blummmmm
or knock thud knock thud knock thud thud vroumph

my 403sbc did it on occasion but it was because it was heated right up after beating on it about 220F itd be a 2-3second run on

LOL... Now there's some diognostic jargen for ya. The second one.

[tvnl]

If your idle mixture is on the lean side richening it a bit will help. Also a high idle speed will contribute to the problem. What is your timing at idle? If it's above 15 or so you can mess with your advance curve to try and lower it some but still have the total you want buy alowing more mechanical advance. Could be bad gas that has lost some octane also.

[Nova_Guy]

This isn't a cure; but if you make a habit of shutting the car off in gear it will help stop it from happening.

[Mike Goble]

The dieseling is typically caused by the throttle blades being open too far.

Increase the initial timing so you can close the throttle blades.

[novaracer1]

Thanks guys, I will try these ideas.

[aron69nova]

This isn't a cure; but if you make a habit of shutting the car off in gear it will help stop it from happening.

works every time.

[DrDenny's 69 Rat]

My car has 11.5:1, idles at 950 RPM and runs 17* initial. Mine will only do it when it's around 200*. Like Mike said, too much throttle,"Increase the initial timing so you can close the throttle blades. I just shut it off in gear about 750 RPM. Better than what it is doing and sounds like. It pretty much runs 180-190*(180* stat) I just do it as habit to prevent those moments.

How can timing have anything to do with it, when there is no spark?:rolleyes:

[tvnl]

Deiseling occurs when the combustion chamber has something in it (spark plug electrode, sharp edge on a piston, chunk of carbon...)that is hot enough to light the air/fuel mixture without a spark when the gasses are compressed. There is no actual spark happening.