Tools, Sharpening and Power Machinery - Dumb question I think? - circular saw smoking!

Ok hello all. Im working on building a speaker cabinet for one of my guitar amps, and having some serious trouble with the circular saw that im trying to use...

this is my dads circular saw - its a craftsman 7.5" thats about 10 years old. now he moved out some time ago so I cant ask him and this is the first time I have used this particular saw so im a tad in the dark. But when I go to cut, it barely cuts at all and smokes like a mother(from the wood), blackening the wood and heating up terribly. let me go through the requisite list of what I have done:

-I made sure the sawblade is in the right direction.
-I tried several new sawblades
-I made sure the cutting depth was right
-I am using the right type of blade
-I even tried the blade backwards for the hell of it.

now I have used plenty of circular saws in my lifetime and never had this problem before. Its driving me batty because I dont have access to another saw right now and I cant figure this out for the life of me. Im just trying to cut 3/4" birch plywood - it shouldnt be this hard! or should it? any ideas what im missing?

I also tried cutting some other types of wood e.g. some thin plywood and 2x4's and stuff and got the same results

You tried several *NEW* blades, or just several "different" blades that were hanging in the shop? Some old timers just can't bear to throw out an old blade. And are these steel blades, or are they carbide tipped? A new carbide tipped blade- even a cheapo one- will cut much better than an old dull steel blade. A burned, smoking saw cut is a sure sign of a dull blade.

The teeth of the saw should be coming up through the bottom of the material, and exit out the top.

two were just other blades lying around and one was an unused blade, although it has been sitting in the package for at least a year - should that make a difference?

all are steel blades, we dont have any carbide ones.

and yeah the teeth are coming up from the bottom

I guess I can try to get a carbide blade at home depot tommorow.

I agree with XSleeper, it sure sounds like a dull blade[s]

I'm one of those guys who just can't part with old blades. Of course with blades that cost $60 apiece, I just stack them up between two pieces of luan with a bolt through them, and take them to the sharpening shop. It may cost me $150 to get 15 or 20 12" blades done, but worth it. My dad would save 7 1/4" blades......why?

-I even tried the blade backwards for the hell of it.

now I have used plenty of circular saws in my lifetime and never had this problem before.
If you have used plenty of circular saws in your lifetime, then you wouldn't have tried that.

Sounds like you are putting side pressure of the saw, trying to cut too fast, or the blades are all dull.