Been teaching myself while building turbokits, ive never had any instruction on how to weld or anything so take it easy and keep in mind im using a 400 dollar MIG welder
Looking good, its all about practice, keep posting from time to time, and if you need input we can assist without being asses 
If you have any questions/concerns about welding call this number, 716 652 0033. My dad and uncle run the place, its general welding and fabricating, I’m sure they can answer any questions you might have… just thought I’d let you know… if you explain your problem im sure one of their welders can answer it… anyways, just saw the post and figured it might help you out sometime… g/l
why are you doing it all with tacks?
Just curious. Doesn’t look like you laid a bead really.
laying a full bead on a 3" piece of round tubing is really tough to keep the distance you want… i was watching horsepower tv a couple weeks ago and they were building a roll cage and showed how to stich a mig weld together, where u basically go quickly around the stock using lots of small welds together quickly to get one good long one, u dont let the metal cool inbetween welds, just keeep going, i welded that whole 3" pipe in about 1 minute, and since your moving faster around and keeping the heat just right you dont risk burning through this thin 16ga material
actually it was Extreme 4x4…but they also debated the difference between laying a bead and continous tacks…and both agreed the bead was prolly better but both are jsut as effective like u said if the metal doesnt cool
just an FYI, stitch welding is different from tack welding. tack welding doesn’t allow much time to remove impurities from your weld puddle and it creates a void as it cools. See the pinholes? granted it’s not a structural weld, so you may not care.
Also, since you were never instructed, theres much more to a good weld than it “not looking bad”
nice, id love some constructive feedback, i like welding shit and i wanna get better with it, i may move into a tig welder next year so i can make manifolds
tig welding is prolly the hardest thing i have ever done in my life, the first time i did i picked up the electrode without letting off on the foot peddle and the arc went to my hand. def not fun…good luck
i have the patience and the dexterity for it, just need the machine… i have lots of scrap metal sculptures at home that i built practicing mig welding
make a tig welder yourself
www.hotrodders.com/forum/my-diy-tig-welder-77730.html
works on steel and stainless steel 
material to start with. 3/8 flat with a 16ga wall rect tube
a “tack” not the best way to weld something structural
layout for a stitch weld
roughly a 2 on 6 (i was doing this quickly)
done. no triggering, and i didnt burn through the tube as you can see because the heat wasnt concentrated on it. if i had a better camera i could show you how goo the penetration was. but you get the point.
one of these days i will make a welding thread so there isnt too much misinformation.
side note: even though the tack weld gets some penetration, just like josh said it isnt alsways a matter of how it looks…you are not evacuating enough impurities in the melt and you end up with a weak or brittle weld. same thing if you were to use too much heat and have undercut.
now when i say stich weld i was doing small 1" sections around then turning the pipe and doing it again, since it needs to be airtight (just an intake pipe) what is undercutting?
undercutting is when a bit of a “ditch” forms where the weld and the material meet