barronj
Bronco Guru
- Joined
- Jun 6, 2009
- Messages
- 1,859
Well, the truck generally runs like a scalded ass ape when I'm driving, but at shut-off, it tends to diesel. Lately, it's been doing it really bad. It doesn't do it when cold, only when up to temps (190, never hotter, always constant (mechanical gauge)). I will admit that my fuel line (rubber) runs from the DS to the PS, laying across the intake manifold (clear fuel filter mid stream), and a fuel pressure gauge lays on my passenger side valve cover. Not sure if these hoses are getting too hot & "boiling" the gas or creating substantial pressures to push them in to the manifold where they're consumed.
All new motor, low 9:1 compression range, aluminum headed 351.
There was 3 month old summer gas in the tank (87), I've since driven 1/2 of that off, added higher octane (93) and some octane booster, hoping this would fix it, but it has yet to.
Timing is at 10 degrees, down from 12 in an effort to curb the dieseling. Some argue that too much timing can cause it, so changing timing to see result is a quick event. It seems to run fantastic at 12.
I took the carb off tonight to see if the primaries weren't all the way closed, and they weren't. The screw that I turned to fix it was the fast idle set screw, the one that the fast idle cam establishes itself off of. I'm going to assume that my fast idle will be lower now, not sure how low. It was the only thing I could positively say was keeping the butterflies open, and backing off 1 full turn got them closed. Will this fix it?
Although the heads were new when installed, along w/ a fresh bottom end, it did run extremely rich for a while, and all the plugs would be black from idling. I've since dialed the carb back 3 stages leaner on the cruise mode & 1 leaner on the power mode. I would have to look at the step-up springs & metering rods to tell you exactly what's in it. Plugs now look normal (off-white, tan) when pulled after idling. Not sure what a WOT cut-off would yield on the ceramic, but that's another day.
I could run some sea-foam or a dribble a large cup of water through the carb & see what happens after.
Anyone have a solid, works every time fix, short of putting a holley on there?
All new motor, low 9:1 compression range, aluminum headed 351.
There was 3 month old summer gas in the tank (87), I've since driven 1/2 of that off, added higher octane (93) and some octane booster, hoping this would fix it, but it has yet to.
Timing is at 10 degrees, down from 12 in an effort to curb the dieseling. Some argue that too much timing can cause it, so changing timing to see result is a quick event. It seems to run fantastic at 12.
I took the carb off tonight to see if the primaries weren't all the way closed, and they weren't. The screw that I turned to fix it was the fast idle set screw, the one that the fast idle cam establishes itself off of. I'm going to assume that my fast idle will be lower now, not sure how low. It was the only thing I could positively say was keeping the butterflies open, and backing off 1 full turn got them closed. Will this fix it?
Although the heads were new when installed, along w/ a fresh bottom end, it did run extremely rich for a while, and all the plugs would be black from idling. I've since dialed the carb back 3 stages leaner on the cruise mode & 1 leaner on the power mode. I would have to look at the step-up springs & metering rods to tell you exactly what's in it. Plugs now look normal (off-white, tan) when pulled after idling. Not sure what a WOT cut-off would yield on the ceramic, but that's another day.
I could run some sea-foam or a dribble a large cup of water through the carb & see what happens after.
Anyone have a solid, works every time fix, short of putting a holley on there?
![0000049.jpg](http://i164.photobucket.com/albums/u27/cbarronj/0000049.jpg)
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