i have a 89 fbird with the LO3 305 tbi. i have a set of 1.94" heads with 72cc chambers to go on it. and planning on putting a comp cams magnum cam in it with . 470" lift. Are there any other mods i can do to this engine.

 

Are you asking for necessities as far as installing those two items go or mods in general? If you do a search you'll find loads of good mods to do if the second is the case. But for those specifically, changing the valve springs is a must stockers just suck, and its a good idea (not needed) to change things like valve seals, pushrods, timing chain. Others have more experience in this and can help you more but either way

 

Those heads will not be a good choice. Your compression will be too low. You need some heads with 58cc chambers. The 72cc chambers are probably for a 350.

 

what he said. Unless your swapping in different pistons then by all means go for it.... Either that or have acess fto free machining.

 

Just taking some random set of heads and slapping it on any engine is always a bad idea.

I'd say do a lot of research before doing anything major. In the mean time, get an injector spacer & do some exhaust mods. Then when you're ready to go with a new head/cam/intake swap go for it. But also - look into prom burning!

 

Well said. I would start with the basics and focus on intake and exhaust mods. I would not use those heads as they won't provide any real gain. The real bottleneck on these cars is the cam and the exhaust. I must add emphasis to whay goy said about DIY tuning. Without chip work the mods that you add to your car will haunt you. Your car will run terrible and never reach its full potential. Take some time to read the stickies at the top of the TBI board. They will clear up a lot of the questions you have.

 

What size are my stock intake valves supposed to be?

 

i beleive 1.84 intake and 1.5 exhaust.

 

Correct.

 

What's tbe biggest valves one can run in a 305 head, and also biggest anyone has run (without problems) ?

 

I run 1.9" intake and 1.55" exhaust in my 081 TPI heads.

 

i beleive 1.94, 1.60 is about as big as you will ever want to go on a 305 head.

 

Heck what I should have asked as well is, can one run say 1.94/1.6 or 1.9/1.55 (latter one may be a much better combo) without replacing the valve seats ? ie by making a larger 45 degree cut or what ?