I want to bore my blazer 4.000 and put a cam kit in it how much horsepower and tourque will i gain? And will i have to change the heads or just piston rings?

 

theres sooooooooooo much more to it then that its insane. you need to do some googling. there is 100 different cams,custom cam grinds,head work etc. its not a simple question. you need to talk to your machine shop,and study a bit more.

 

total rebuild...that is what your looking at. with just a cam you will need valve springs minimum...and thats for a mild cam...then you will need your pcm tuned as well.
look at v8 swap for ideas as well.

 

Ok guess i might get a pcm tune. And how do you get these things to do a burnout or squeel tires when you pull out because ive tried doing a burn out but it wont work lol and my dads 94 sierra will squeel 33s no problem

 

I can spin my 31s all day if I want! All I do is push the pedal and that's all it takes

 

Are you saying you want to bore your 4.3 to 4"? The 4.3 already has a 4" bore. I wouldn't bore it just to gain power. Even if you went 60 over it would only gain you 8 c.i. and take away any possibility of future rebuilds. Plus, you would have to buy new pistons and rings, and get the whole thing balanced.

As for the cam, summit lists 37 grinds for a 4.3. Each will produce different values and curves. And, depending on a host of other factors, such as gearing, torque converter, tire size, and cylinder head a "big" cam could actually slow your truck down, and make it a dog to drive around.

 

check out hot rod magazines i did a build much simular to this one and was vey happy, but u have to do away with the ecm and go with a carb to get any horse out of a 4.l the spider injector is very limited on what it can do. which means either gett a cableshift 700r4 or get the carb conversion kit for the 4l60e that will allow you to run the 4l60 off a carbed motor

Chevy 4.3L 262ci V-6 - Engine Build - Overview - Tech - Hot Rod Magazine

also in the early 90's like 92 or 93 they did make a 4l60 cableshift that they put in some of the fullsize pickups with the tbi, that will also work. also have heard u can swap the guts out of a 4l60 and put it in the 700r4. not sure if its true but its def worth looking into, i belive the 4l60 is an upgraded r4. not sure though

i eneded up finding a 4.l out of a astro from 85 that was carbed, got a 95 vortec with a tbi on it and put the astro intake on it. did a conversion to a 1.6 roller milled down the heads so i could get 58cc combustion chamber, ran flat top pistons and ran the conrad rods, rapped 6k easy ran like a rapped ape.
i sparked knocked so i ran premium, put octane booster in it, would run racing fuel when i went out playing.
call a cam place tell them what u got and they will hook u up with a really good cam for what u are doing, i find comp is the most knowledgable
did it all for like around 1k but i did most the work myself took in the head to have them polished and milled. but my block was in specs, so that saved me alot of cash money.