[&:] most likely youll find 4-6 deg of initial advance at a 750 rpm idle speed is your happy place with 36 total at 2500 rpm +- and up. 900 rpm as an idle speed will be too high unless it has a pretty wicked camshaft in it and with just 290 HP i dont think thats the case. the explosion, and thus hot bits o carbon, are there as long as the engine is running regardless of the timing being +- a degree or two on many occasions ive watched the engine rotate backwards when dieseling(wonder what the timing is then)?? timing is the introduction of the spark to the cylinder and when run on occurs we have already turned the ignition OFF (so how would timing have an effect)?? carb fuel mixture on both the idle circuit and primary will also effect dieseling by either being adjusted lean on the primary causing higher than normal cylinder temps making it more likely the carbon bits will be hot enough to act as a spark plug or too rich on the idle making it more likely to leave excess unburnt fuel in the cylinders at shut off. most of the basic tune up adjustments mentioned in this thread can have some effect on dieseling so make your adjustments and then let us know if its still happening. ALSO im not necessarily a huge fan of the manual choke as usually most people forget to pull the choke back off or leave it on too long and both conditions tend to carbon up the cylinders and well that leaves lots of little spots that can act as spark plugs. remember fire or explosions require three elements air, fuel and ignition source. do you have points type distributor or hei or aftermarket?? kurt

 

Accel Hei dist. The camshaft is not wicked, but definately a step up from stock. I believe they take a corvette cam and isnstall into a stock 350.

 

Kurt
Have you never seen an exhaust manifold glow cherry red on a stock or any engine? That is usaly due to timing being retarded. It is making the excessive heat. I had redneck friends that swore by timing their cars by ear. Every one of their cars dieseled. One was so funny it had to go on for near a minute. I checked it with my light and found the timing way off.
The fedral specs for a 4bbl 350 is 6 degrees and 00 rpm in drive on an automatic. 700 in neutral for a manual

 

You said you were an ASE master tech huh........ Well I was searching and found this since you would never believe what I say because I spent my money on getting educated and not a certificate. Read (3) F
http://www.mgaguru.com/mgtech/engine/ro101.htm
And acctualy I did not have to pay to learn any of the reasons for run on. I learned it in high school auto shop.

 

Carbon build up in the combustion chamber, and timing are the two likely causes. Are there many miles on your crate engine? There is another thing that can cause it if you have the right components. My 69 has an MSD ignition, and I also have an electric radiator fan that runs on keyed power. If I shut it down with the fan running, I get a diesel type of run-on. What is happening is when I kill the engine, the fan is still free wheeling and acts as a generator, feeds power back to the ignition and the engine still wants to run...momentarily. I have a kill switch so I can shut the fan off first, let it coast down, then shut the engine off and it's fine. Don't know if you have an electric fan or a high output ignition, but I thought it was worth mentioning.

 

[&:] kev79 hei's are great and are much less likely to create conditions that contribute to dieseling. Make the basic tune up adjustments and ill bet your problem goes away (idle speed, idle fuel mixture) mike this ASE Master has read F not 3f and if YOU read and understand the entirety of the section he is talking about the effects of advanced or retarded timing in a RUNNING engine, thats it. Opening sentence ( Spark timing advanced too far can cause pinging and detonation,) Not really sure why F is included as a section in this article as the author fails to draw a correlation between timing and run on, it does give one possible cause of red hot manifolds though. Am i missing some assembly of words that tie the two together in section F???? Remember its run on or dieseling were talking about. Section 3 is a subsection of E with F being its own separate point. The lettered points being the main points and numbered ones being subsections(should be switched around ) Section E, and its subsections( 1,2,3, Not F) is all about physical engine flaws being ignition sources and causing detonation and dieseling. So as ive stated engine timing itself will have no effect on run on or dieseling,, it may contribute to that which could cause hot spots but IS NOT a direct cause of our problem. if you continue with your theory then every engine part could contribute to poor combustion and carbon build up and thus an ignition source for the shut off engine. Maybe a little more of your money should have been spent in the reading, comprehension and where ideas and subjects get separated at. As for the red hot manifolds, ive seen plenty and most were not supposed to be(retarded timing, lean air fuel ratio) you want the heat in the cylinder not the exhaust. except for some high performance applications your **** shouldnt be red. If your gonna bother to find and quote scripture make sure it at least proves your point (even if your wrong) I would think the educated and articulate shouldnt have to pull non pertinent info from the internet to fail to prove there educated point

 

[&:] Camaro 69 good story that may serve as a reminder why its a good idea to use auxiliary circuits to power auxiliary items like fuel pumps, lights, nitrous and especially fans to avoid feedback problems and power demands through appropriately sized wires. If a relay had been used your problem would not have been, i think they are a very underused tool in the resto and udgrade hot rod arena. seen how many are in newer cars??? kurt

 

Kurt your good at posting a bunch of BS. Its a lot of hot air. You could be O.J.'s next dream team.
That person wrote about run on and what could cause it. That person listed ignition timing as one of the causes and the effect it has when it is out of spec to far. Yes I goofed and edited my post adding 3 to it but I was scrolling and wanted to make sure you saw the correct area I was pointing out. I should have just left the F in my original post.
Bottom line is if the ignition timing is off it can cause run on. It starts with the timing off and ends with run on. The effects it has in between are unimportant.I am sorry you do not understand my simple explainations. A person would think with the big brain on you it would be easy. But I guess not.

 

well at least your adament in your convictions. did OJ or anyone ever win a contentious point or legal argument by declaring the other side as full of BS and hot air??? ever see a computer controlled car run for more than a half second with timing so far out it caused dieseling ??? ok lets go old school how about a carbed model exactly how far out of adjustment do we need to go to get the undesired effect and honestly how well did this vehicle run in this state of maladjustment. im not a rocket scientist as im sure you'll attest to but i dont think even the great mike can argue that there are three elements that make things go boom air, fuel and ignition. Nope timing aint in there so ill ask again how exactly does the timed introduction of a spark (from an ignition system thats off read: not from the sparkplug and therefore no such thing as timing at this point) have any effect on an engine running backwards in most cases as i dont remember seeing many diesel in correct rotation and if they did it was from the FUEL AND AIR(not timing) it was still getting from improper tuning and or adjustments. please enlighten those of us with such inferior educations with an eloquent diatribe that would certainly highlight and showcase your superior intellect, on how exactly this happens and or has any effect. If nothing else please explain EXACTLY how your theory about timing works cause I, for one, am just not getting it, I dont think you have explained anything yet

 

I know you are not getting it. You most likely never will. I posted a link that expalained everything. It looked like it was clearly written and understandable. Look in your Chiltons or haynesin trouble shoot under run on and I bet you will see it say to check or adjust timing. I just looked in two of my manuals and it says among other things to check timing. Why would it be in print if it has nothing to do with run on. Read that link again. The whole page is about run on/ deiseling. You act like things are set in the stone in your head. That link had a great explaination but clearly you can not understand so there is no explaing things to you.