Adjusting Weber for large elevation changes?

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MrWrench
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My tercel:: 1985 Tercel SR5. aka Spud
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Adjusting Weber for large elevation changes?

Post by MrWrench » Fri Dec 20, 2019 5:06 am

Hey guys, I am taking Spud with 3 dudes and a load of spare parts and camping gear out to Colorado and driving through the rocky mountains this summer. The trip will be about 3,500 or so miles.
My car is currently tuned pretty well for where I live. Which is 800 feet above elevation. Looking into my route and the town's I'll be staying in have a elevation of 6,000+ feet with possibilities of getting higher than that.

So I am wondering if you guys think about tuning adjustments for the elevation changes.

1. Jets
Do you guys think it'll be okay with the factory jets?
A jet kit is relatively inexpensive, but I don't know if it'll be necessary to do.

2 . Air fuel ratio.
I was thinking about getting a wide band oxygen sensor and gauge. They're pricey, but it would be nice to know how the car is responding and adjust it accordingly.
And if I decide to run a wide band, what is a good reading I should maintain between and a maximum/minimum air fuel ratio I should run before I have pinging and detonating issues?

Thanks in advance everyone!
1984 Toyota Tercel SR5 winter driver rescue
1985 Toyota Tercel SR5. Daily driver. Aka "Spud"
1986 Toyota Tercel SR5. - Recent wagon rescue/project.
* ISO - any 4wd manual transmissions *

The Professor
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Re: Adjusting Weber for large elevation changes?

Post by The Professor » Mon Dec 23, 2019 8:17 am

I'd suggest keeping the AFR as close to 14.7 as you can, leaning toward 13:1 or "rich" for safety. Anything above 14.7:1 is considered "lean" and could cause detonation.
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teranfirbt
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Re: Adjusting Weber for large elevation changes?

Post by teranfirbt » Mon Dec 23, 2019 10:40 am

Back when I had my Weber I had it tuned well for near sea level and then took a trip to Texas. It did just fine without any adjustments, ran pretty rich in the high elevations at high loads, but otherwise did well. If it's only a road trip, I wouldn't worry much about a trip over the rockies, it'll be fine.

wild scallion
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Re: Adjusting Weber for large elevation changes?

Post by wild scallion » Wed Jan 29, 2020 12:21 am

It may or not be applicable to your route, but for elk hunting at 10500ft I had two seasons of trouble getting that high. The third year we added a fuel line onto the unused side of my weber's "t" just before the carb, and had a hand pump and pony tank (our "Icarus tank") to manually add fuel into the carb. Worked great, really. Did it make sense? unsure. But if you were going that high for any length of time, a fifty dollar prepared setup might be useful for that cause.
Between 9500 and 1500 feet throughout travels I didn't notice any glaring performance issues. (Maybe due to the steepness of the slope, too..)

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MrWrench
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My tercel:: 1985 Tercel SR5. aka Spud
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Re: Adjusting Weber for large elevation changes?

Post by MrWrench » Tue Apr 28, 2020 7:47 pm

wild scallion wrote:
Wed Jan 29, 2020 12:21 am
we added a fuel line onto the unused side of my weber's "t" just before the carb, and had a hand pump and pony tank (our "Icarus tank") to manually add fuel into the carb.
You've intrigued me with this information.
Recently I installed an electronic fuel pump to try and help.with my horrible no start issues with my Weber carb. I believe I am somehow losing fuel from the bowls after a while.
Now with the electronic pump, I can just let the car prime itself for 15-20 seconds and it starts effortlessly.

My questions are this, did you have to adjust your fuel pressure for the second line? And did you just run a line directly into the open secondary port in front of the Weber? Or did you just T off your line from the pump/pressure reg to the other spot? I am genuinely curious and would love a photo if at all possible.

Thank you so much everyone for your responses!
1984 Toyota Tercel SR5 winter driver rescue
1985 Toyota Tercel SR5. Daily driver. Aka "Spud"
1986 Toyota Tercel SR5. - Recent wagon rescue/project.
* ISO - any 4wd manual transmissions *

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