Just got a 91 firebird..305 tbi, auto..it has a bad valve seal so since I'm taking off the heads i figured I might as well upgrade to some vortec 059s. My question is does anything need to be swapped on the heads to work right? Like is there any weak components or anything beneficial I can do to them while they are off (porting, polishing, etc..)? I dont know much about valvetrain stuff so bear with me...Im gonna be going with a carb intake too since the egr is coming off (no smog test)

 

There are better springs that will fit them. You could also put offset retainers as well to get more lift. In stock form, the max lift for the heads I had was exactly .450". Anymore than this would cause the retainer to contact the seals. The springs also suck big time. Theyre 80 lbs seat with 200 lbs open. Not much pressure. There is some info in the archives on how to do to swap out the springs for better ones. Bear in mind that you will want to measure the heads with the retainers that you will be using to verify the installation. I recall the heads having different I/E spring seat hights on my 062's (have not had any experience with the 059's) to accomodate a hardened exhaust valvestem face. If your using different retainers and/or valves, this can cause issues with spring hight. It also limits the retainer clearance as the valve guides are all at equal hights. I would strongly recommend having machine work done now to resize the guide and seats and level them out.

As you stated, you will also need a vortec intake.

If theyre used, you may also want to clean and magnaflux them to be sure there are no cracks. Obviously do this first before any machine work is done.

 

I have heard polishing the exhaust is worthwhile on those heads. I would swap out the cam as well.

 

polishing intake ports wouldnt help?

 

I have a low mileage set I'd let go for $150..

 

That's a good deal.

You don't want to polish intake ports. The rough areas in the intake help to atomize fuel.

 

ok...well i havent got the heads yet..but ive been looking around on the site and saw that another option is the 113 aluminum heads. Does anybody have any links to posted results of these different heads on a 305?

 

You can smooth things out around the valve seat, bowl, and the guide. There are some rough spots which seem to be worth 10-15 CFM when you smooth out the transitions. You then follow up with a coarse grit on the intake ports to help generate turbulence near the wall to help keep the fuel suspended.