One thing for sure, blue smoke=oil, it can't be fuel (too rich = black smoke), maybe a problem with the pcv valve (didn't check if you changed it or not)? Have you tried venting the pcv to the atmosphere instead of returning it to the intake manifold to see if it made a difference? You have changed the oil since initial start up? What do your spark plug look like? And fuel economy?

 

Unburned and partially burned fuel are different smoke colors. Right? And yeah I tried venting the pcv to the atmosphere. Also I change the oil 3 times so far.

 

Plugs seem fine. Usual tan color. But only 800 miles. And I haven't checked fuel economy yet. But my guess is close to 18 mpg

 

I'd be very surprised if it was anything carb or fuel related. I think you need to do a leak down test if you haven't already.

 

Yeah you maybe right I'm no expert. But driving it yesterday it seems like it the carb. The smoke doesn't change with rpm like I thought. It changed with how much fuel I dump down it and waste.. So when I'm shifting and I have a lot of throttle and let off I'll get smoke. And if I'm under load and full throttle then she smoke. But if I hold it at like 3k with little gas and shift or let off the throttle very little if any. I've also been noticing that's when driving around if I go slow in first or second and give it gas, it gives jerks (lunges forward) the. Smoothes out.

 

Also yesterday I went up a very steep hill on the road at around 2000rpm maybe a hair lower, with full throttle and I saw pure black smoke and at the top when I let off the gas it turned the grayish white.

 

Well...tune the carb.

Then worry about the engine if it doesn't stop smoking.

 

I think I would nix that Weber 38 and go with a 32/36. That 38 dumps fuel through one barrel throughout the RPM range while the 32/36 uses primary and secondary barrels. You're likely getting extra fuel that isn't needed and goes unburnt or lightly burned without an adequate oxygen supply. Part of the problem with the 38 is that since it is a single barrel carb, it is not tuned to for the whole RPM range so there tends to be a "sweet spot" in the RPM range where it is tuned perfectly and performance/tuning degrades as you move up or down the RPM range from that sweet spot. Ideally, you'd tune that 38 to an RPM range that you are driving the most in - say around 3,500 RPM for highway use and maybe around 2,500 for around town use. Either way, your idle will tend to be a little lopey or unstable since it isn't tuned for optimum performance at idle. The 32/36 is more fuel efficient and easier to tune. It uses primary jets to maintain a constant and if more power or acceleration is need, the secondaries come in to play with a heavier push of the pedal - sounds good too! :o)

 

Yup. Works just like the stock carb, except much more simply. Not many people have 38s on these little trucks.

 

Yeah I was thinking I was going to get a 32/36. You guys think my theory about the carb makes sense? I've true tuning it but it doesn't seem to help too much because it doesn't have enough adjustment. I'm thinking it's an internal problem. Where can I buy a real weber carb? And am I correct fuel smoke can vary in color depending on how much it's burned?

 

I don't know.

I know my truck was leaving a black soot mark on the pavement when I'd first get it warmed up...but it didn't seem to smoke after it was warmed up.

I have a rebuilt carb on it now but I haven't fired it up yet since I put it on. It's trying to be winter here...2wd camper not so good once there's snow on the ground.