IDI at altitude??

[JwS]

I recently moved from the east coast (altitude 0) to salt lake city (altitude about 4500'), So I am dealing a bit with overfueling from the less dense air, it isn't a big deal at 4500, but when I climb up to 7000 and above, which is fairly common out here, I get the black smoke and the temp starts rising. So far I have been using the eyeball pyrometer on the exhaust and I back off to keep the smoke level reasonable, and the temp under controll. I am thinking of backing off the pump to compensate, It would be easier than watching the smoke and I am wondering if it is the better solution. Of course the down side is that when I go to low alt I will be down on power.
So does anyone have an opinion on this in general, an idea how far to adjust (so I don't have to open it too many times)?
I know a turbo would be the nice solution, but I am not gonna be able to afford that right now, oh well!
JwS

 

[ClassicIDI]

I live just on the other side of the rockies from ya so I know how you feel. I have never driven and IDI at sea level so I have no comparison but. I did turn my fuel pump up a while back and have had no problems. before my truck would not smoke no matter how hard I tried but after I turned the pump up it would smoke as soon as I put my foot in it and has waaay more power than before. I have a egt guage and empty I can not get the truck over 1200 but with a trailer in the mountains I have to watch that guage or it can get in the melt down range. if you can live with the smoke I would leave it be and get an egt guage. If not you can turn it down a little at a time to get a good comprimise. I turned mine up 1 1/2 turns for a reference.

 

[Agnem]

Turning the pump back is the same as taking your foot out of it. Just stick a piece of wood under your accelerator pedal.

 

[hoodshauler]

Just stick a piece of wood under your accelerator pedal.

hey now i have the patten on the wood blocks
Oh wait you said under the accelerator not on the clutch pedal.

 

[Exekiel69]

hey now i have the patten on the wood blocks
Oh wait you said under the accelerator not on the clutch pedal.

Here we go....

On topic, get a pyro and then see if You really need to turn the pump down.

 

[Diesel JD]

I agree a pyro is a real good idea, shoot for below 1150, maybe 1100 as a max safe temp no further than 3" from the manifold.

 

[Mont91]

Remember that black smoke is wasted fuel and contamination in the oil. To much over fueling reduces HP. A nice gray smoke is best under full load.

 

[JwS]

I let it smoke a little, and back off when it starts getting black. It is only really a problem above about 7000 ft or so.
Well I guess for now I will leave it as is, and use my good sense. Perhaps a pyrometer would be a good idea too.
I'd rather not screw with it, since it is a van I have to pull alot of covers and kind of crawl on top of the engine with mirrors and lights and stuff to get to the pump!
Thanks all.
JwS

 

[IHWillys]

Turning the pump back is the same as taking your foot out of it. Just stick a piece of wood under your accelerator pedal.

However, the amount of advance for a given amount of fuel will change with pump fuel rate changes. So 'turning the pump down' could be beneficial vs going lighter on the go pedal as it will change the timing advance for the same amount of fuel delivery.

Ken

 

[RLDSL]

Turn the fuel back a notch and advance the timing a little . Probably have to experiment a bit to get it feeling right.
I don't know why ford and stanadyne never figured this out on these things. ( well, I suppose that's what the pumps labeled 'high altitude ' are for ) Back in '84 Volvo started putting an altitude compensator on the bosch pumps on their diesels that performs that little task automatically when you get up to altitude. It does wonders ( driving the pre altitude compensator models at high altitude gives you a strong urge to get out and push )

Get a pyrometer on it to keep out of trouble.

-----------Robert

 

[Agnem]

The advance cam on the outside of the pump only affects lower RPM's. Once the RPM's are high enough, timing advance is regulated by the internal fuel presure acting on the advance cylinder, which overides any external cam setting . This is why you time the engine at 2000 RPM's. So in theory at cruising speeds, the throttle position has little to do with the timing, and fuel presure and not fuel delivery rate is the regulating factor.

 

[JwS]

Sounds good, I'm gonna leave it be, and keep thinking about a turbo...
JwS