225 v6 "dieseling"

[garage gnome]

Lately, my 225 v6 has been "dieseling" after I shut it off. It hasn't done it before. I have an HEI on it. I pulled out a plug and it looks like it was getting pretty hot. I have also ordered a carb rebuild kit (stock 2g) since it has been stumbling off idle and doesn't idle as well as it used to. What are some cures for this issue? My plug gap is .035". Should that be increased?

 

[3b a runnin]

I've had some issues with dieseling also. My 225 has a 4 barrel carb on it. I don't know the cure but using premium gas has stopped the problem.
Hopefully someone who knows more that me (almost anybody) will answer your question.

 

[Oldpappy]

Dieselling can have several causes, most commonly it is the timing may need to be advanced a little

What spark plugs are you using?

If using standard copper core plugs for a stock 225 you could try setting the gap wider, maybe up to .045

How long has the HEI distributor been on it?

My 225 has a breaker point ignition, so I am just throwing this out.

I noticed that Jeepsterman sells different plugs for the 225 V6 depending on whether it has a HEI ignition or breaker point ignition.

https://thejeepsterman.com/products...MI5MWo26--kgMVNEP_AR39uCZBEAQYASABEgLVPfD_BwE

 

[matt johnson]

I've had some issues with dieseling also. My 225 has a 4 barrel carb on it. I don't know the cure but using premium gas has stopped the problem.
Hopefully someone who knows more that me (almost anybody) will answer your question.

Exact same here. Timing checked, carb checked, dwell, etc. 225 completely stock. Put premium gas in it....
No issus since.

 

[garage gnome]

Dieselling can have several causes, most commonly it is the timing may need to be advanced a little

What spark plugs are you using?

If using standard copper core plugs for a stock 225 you could try setting the gap wider, maybe up to .045

How long has the HEI distributor been on it?

My 225 has a breaker point ignition, so I am just throwing this out.

I noticed that Jeepsterman sells different plugs for the 225 V6 depending on whether it has a HEI ignition or breaker point ignition.

https://thejeepsterman.com/products...MI5MWo26--kgMVNEP_AR39uCZBEAQYASABEgLVPfD_BwE

I am using stock plugs for it and the HEI has been on it since I put it together in 2020.

 

[matt johnson]

Ok, so Ayden just mentioned that regular gas had a higher obtane back in the day. So I googled it. Sure enough regular gas in 1971 was 91 - 94 octane .

 

[colojeepguy]

Ok, so Ayden just mentioned that regular gas had a higher obtane back in the day. So I googled it. Sure enough regular gas in 1971 was 91 - 94 octane .

I think that was a different method of calculating octane rating.

 

[PeteL]

Make sure the carb is shutting down freely and fully at idle. Check the dashpot function, cable range, choke linkage, etc.

A tiny bit of throttle plate opening will allow dieseling.

 

[Beach66Bum]

For me, my timing was a bit to far advanced, causing “dieseling”
Set back to 5*, problem solved.

For a hotter spark with HEI, you can open the gap up. Same when using Pertronix.

 

[53A1]

Stupid question but what is the water temp gauge reporting?

 

[3b a runnin]

Don't know about garage gnome, but mine is pretty consistent at 180*

 

[garage gnome]

Stupid question but what is the water temp gauge reporting?

Between 180 and 210 degrees. The operating range of the electric fan thermal switch.

 

[timgr]

Will your engine stall if you back out the idle stop completely?
It should.
You could apply the solution the manufacturers used and add an idle stop solenoid.
The pintle extends with the key on, and retracts with the key off.
Then the position of the energized solenoid sets the idle speed, and the closed throttle plate stops the engine.

 

[Ol Fogie]

For me, my timing was a bit to far advanced, causing “dieseling”
Set back to 5*, problem solved.

I am no wizard here but I think those little dark spots on the spark plug ceramic insulator is an indicator of too advanced timing too. They are a symptom of detonation even if you cannot hear it. which can also cause dieseling and spark knock associated with lower grade ethanol fuel?

 

[Kaiserjeeps]

Look up the plugs for a 1976 oddfire 231 V6 with the HEI. Or a later Buick 350 in a skylark with HEI. Make sure you put those plugs in and yes your gap can and should be opened up to gain the benefit of the HEI. And what PeteL said. Make sure your throttle plates are mostly closed at idle.

 

[53A1]

My Dauntless would diesel if it hit anything higher than 210 and I shut it down. I've since then solved my overheating problem. Problem gone.

 

[MeAgain]

Warm up yoir engine.
Run the engine at 2000 rpm.
Get a water hose and trickle a stream of water down the carb.
Increase volume of water until engine runs rough then add a bit more rpm's until engine smooths out.

Hold that flow and rpm's for a few minutes.

This was a common solution for cars in the 70's and 80's that experienced run on.

Maybe it will work. If not look elsewhere

 

[3b a runnin]

Warm up yoir engine.
Run the engine at 2000 rpm.
Get a water hose and trickle a stream of water down the carb.
Increase volume of water until engine runs rough then add a bit more rpm's until engine smooths out.

Hold that flow and rpm's for a few minutes.

This was a common solution for cars in the 70's and 80's that experienced run on.

Maybe it will work. If not look elsewhere

I have done that before, but not on this engine.

 

[WYOMIKE]

The following is in the FSM.

Mike

 

[garage gnome]

I'll try rebuilding the carb first because that has been giving me problems and I'll see what happens from there.