jetting the holley 2280 for high altitude

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jcricket

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May 3, 2016
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Ram Year
1985
Engine
5.2l
Hey Folks,
I have a 1985 w250 318 auto. it has the 2280 2bbl on it. No computers on this truck, naturally aspirated. I just rebuilt the carb. She runs way better but I still need to tweak her a bit.

At idle in park she runs smooth and quiet. In park she revs up pretty well. Under load she stumbles a bit. I am going to check timing and likely advance it a few degrees. I think that will be a significant help. I am also going to play with the idle fule mixture screws a bit.

Even so, she smells very rich. I have #80 jets in the carb now. That just seems pretty large to me. I am in Denver so most of my driving is between 4500 and 6500 feet.

I have chased down most if not all of the vacuum leaks. I will double check this as well. Just an FYI, I have rebuilt many carbs and done a fair amount of reading on them. I grew up with cars and no computers. Old timer mechanic here.

Anyone have an idea what size jets should be in her? I will likely buy a ten pack of the bay and just experiment a bit.

Any suggestions will be appreciated.
 
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jcricket

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Ram Year
1985
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5.2l
Just an fyi to those of you who have the 1985 318 w/holley 2bblo. The idle fuel mixture screw is cover inside a casting with a small cap. I cut half the casing away and found that the screws can be adjusted using a 3/32 allen wrench. I'll post pics tomorrow of the cutting. I used a simple makita with a cut off wheel. I am certain a hack saw would work as well or better.
 
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jcricket

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Joined
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Ram Year
1985
Engine
5.2l
I have located a second carb. It appears to be the exact same one on my truck. I gave $20 for it and bought a rebuild kit.


Something really weird . the jets are marked 307. I can't measure them but they look like any other holley jets.

Anyone here know what these jets are? Any idea on size? I'll likely just rebuild it and put it on the truck to see what happens. If it gives me a headache, I'll swap in the 83's I have from the oem carb.
 
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