my 81 fj60 w/ 190k does not do well going up hill from 5000 to 10000. i have the HAC lines disconnected so that shouldn't be a problem. advanced the timing to 13 degrees. valves adjusted not long ago. i am running 33's on stock gears, but maxing out at less than 40 in second going up hill. possibly the vaccuum secondary in the carb? is there an easy way to check its operation? i run 85 octane. my thoughts are either carb problems, or the 2f can't turn 33s at high alt. anyone know about any of this?
high altitude performance (carb?)
- Thread starter btarp
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Get used to it. 
4.11s will help a lot, 33" tires are a bit much for the stock gears and those conditions. Can you feel the secondary open? I doubt it is your problem, do a full tune up and get used to the slow lane.
4.11s will help a lot, 33" tires are a bit much for the stock gears and those conditions. Can you feel the secondary open? I doubt it is your problem, do a full tune up and get used to the slow lane.
The HAC does more than just advance the timing. It adds air to the carb to improve the air/fuel ratio.
Have you done a compression test lately? Power falls off with reduced compression.
The only way I know to check the secondary is to remove the housing from the side of the carb. Stick a tube on it and suck on it. If its leaking, you can feel it.
And... the right lane is your friend. The left lane is for people with car payments.
Have you done a compression test lately? Power falls off with reduced compression.
The only way I know to check the secondary is to remove the housing from the side of the carb. Stick a tube on it and suck on it. If its leaking, you can feel it.
And... the right lane is your friend. The left lane is for people with car payments.
Status Normal
My engine was recently rebuilt and the carb and distributor were done by Jim C. I desmogged the motor so the HAC is gone. I ran it for a few weeks with stock tires and then went to 33's. The top end power went to hell. Mileage and low revs on the highway are better, but it is definitely life in the slow lane on the hills.
My engine was recently rebuilt and the carb and distributor were done by Jim C. I desmogged the motor so the HAC is gone. I ran it for a few weeks with stock tires and then went to 33's. The top end power went to hell. Mileage and low revs on the highway are better, but it is definitely life in the slow lane on the hills.
Even with a perfect engine and carb you will not get enough vacuum at higher elevation to open the secondary. 35-40 mph going up the mountains is normal. I always run higher octane as well. Mine doess't like 85.
Agreed, and get used to it. I usually run in 2nd or 3rd gear going up the steep (up to 13K) mountain passes in the San Jauns, and sometimes even drop below 30mph, but those winding roads are not designed for high speed travel anyway. This in in a mechanically perfect 87 FJ60, which has a new carb and has been compression tested 150 psi on all 6 cylinders. The h55f helps when I'm off-road with the extra low range first, but the 5 gear is pretty much useless when in the mountains.
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Two thoughts. first, it is is 25 year old truck w/ 190K miles. That is not helping.btarp said:
Second, the vehicle is being operated at high altitude and for unknown reasons the HAC has been rendered inoperable. that needs repaired to get the fuel mixture back toward optimal. At 10K feet w/ no HAC function, the engine is drowning in fuel.
The vac secondary diaphragms last about 15years. If the carb hasn't been rebuilt in the last decade, then it is suspect.
Could be both.
