I read so many threads here and on other boards about engine dieseling, there were a lot of questions and suggestions but rarely did the person with the problem come back to the thread with what worked to fix it.
I almost started a thread here several times this last year but in the end figured it out from research.
I have a 76 K10 350 with vortec heads, it has a mild torque cam with around 9:1 and 8,000 miles since the rebuild. I have a new hei, edelbrock intake and 1405 carb etc.
It has dieseled the whole 8,000 miles but runs very strong despite, so in desperation I made an ignition cut off switch on my dash and killed it in gear. I hated shutting off my truck only for it to spit and sputter for 5-10 seconds(Uncle Buck lol).
I tried everything I read online, I looked for vac leaks, installed a FPR at 4.5#, a step colder plugs, lowered idle speed, readjusted floats, higher octane fuel etc. and nothing helped.
I was at Orielly's and an employee I have known 2 years to be good with old cars suggested I retard my timing. He said if its to far advanced it will run hot and can caused dieseling.
So I went from 12btdc to 10 and when that didn't work to 8 which still didn't help. I toyed with the idea of 4btdc which is factory spec in many manuals but gave up and just started cutting it off in gear again.
Last week I started getting fed up again, it dieseled so bad that sometimes when I cut it off in gear it still tried to run causing the truck to lurch forward! So I did more research and saw a guy suggest calling edelbrock tech, he said they helped him fix his problem which ended up being a carb issue.
The tech guy said he didnt think it was a carb issue but related to my timing. He said the exact opposite of what the Oriellys guy said, I needed to ADVANCE my timing to between 12-14 and that it would run better and cooler.
Which made sense to me because the truck was always faster at 12btdc, so out came the timing light and I bumped the timing to 14, readjusted my idle to 600 and put some 91 octane in for good measure and NO MORE DIESELING!!!!
Only been setup like this for a few days but I ran it around the city and highway on Sat. and had no problems with it. I also floored it which I rarely do and it SCREAMED, I was shocked at how hard it took off when the secondaries opened up.
Hope this helps others in the future with the same problem who are as frustrated by the lack of conclusion on threads as I was.
1
