Just picked up an 80 4x4 and am working out some kinks etc. I've decided to run the truck on the stock carb but think that I may need to lean up the main jet a bit. Reason being is that I'm about 4000 feet above sea level. Does anybody know the size of the stock main..... And also where I could find alternate sizes?

 

Hey there Oilspot..... Did you ever find a source for the smaller main jets? I have an '82 that I am also trying to find a smaller jet for but having ZERO luck.

 

I have sometimes lo temp silver brazed jets closed and redrilled them.
You need a good unmutilated set of number drills to use to gauge the existing hole; so you can decide how you want to redrill.
A very small change does a lot.

 

I'm using Weber jets on my 22R carb prim. on a 20R/22R eng. I think I ended up with a #18 on the prim,. tuned with my LC1.

Loosed spring on the top the sec. plate to about 5 o'clock. Truck has never ran better. I'm at 2200 ft.

 

Isn't part of the point of the stock carb that it compensates for altitude? I've never known of anyone re-jetting a stock carb. They do it all the time with Webers, though.

I have some vague memory of maybe some stock carbs not having the high altitude compensation equipment in them...I don't know. I've always lived in the intermountain west (since I started driving) and every truck I've owned with a stock carb does fine at whatever altitude.

 

FYI, Canadian 4x4 carbs never had altitude compensation. If you modify the engine, re-jetting is typically required to dial it in.