whats the most lift on a cam that i can achieve with stock 305 heads with no machining?

 

I want to say no more than .500, but it depends on how many miles are on your valve springs, and how they have been treated. With stock heads you probably shouldn't have too wicked of a cam anyway. You could have an awesome cam profile but it won't do much on a restrictive head like what you've got.

 

Yea i think more of a limiting factor is how well the heads flow. The kinda cam youde use with heads like that to work well wont put your heads to the limits of its lift. Also concider there is valve to piston clearances to keep in mind but again i dont think it will be an issue if the cams choces properly.

 

well the car is fairly low miles and im gonna go through it and do the rings and rods and mains. im not looking for serious performance i just want something with a little more than stock. do you think that maybe just going to 1.6 rockers would be better than a cam swap?

 

I would say your probably right. People get carries away with big race parts and usually end up regretting it. You might be better off with with a cam though depending on what the specs on your motor are?

 

1.6:1 rockers won't help much on a stock cam.

You don't want to do anything over a stock cam with stock valve springs.

You need to keep lift under .480" unless you do something about valve travel.

Are you talking about rebuilding a 305? If it has fairly low miles and has been reasonably maintained, it shouldn't need rings and bearings. Your user info says "406 small block" - are you talking about putting 305 heads on a 400?

Need to understand what you're working with here, and what you're planning on doing.

 

no this is a diff car. its all stock. 88 305 firebird tbi. the reason for putting rings in it is it has some leaks and im gonna replace all gaskets and being as i work at napa and get parts for cost i might as well freshen it up while im at it. i just want some mild performance and keep the tbi and everything and end up with a nice cruiser that i can take out of town and still get some decent gas mileage

 

Well concidering factorycam specs are pretty lame you have 2 choices go the 1.6 rocker route or a biger cam. Now the factory cam with its short duration leads to it hitting its peek efficiency at a low rpm (usually they operate well in the idle to 3k or 3.5k range) which is terrable for high end hp. However its great for low end torque, driveability, and fuel economy. Now the lift on the other hand is also terrable however there is no upside to having low lift that i can see. Installing high ratio rockers will maintain the same basic operating RPM range but yeild more performance in that range. The other option is the cam. Here you have the opertunity to actually shift the RPM range you want it to work over. Now the higher you go you will trade some low end torque for high end hp so its a matter of finding a balance. For you concidering you not looking for a screamer i think youve be happy eather way. The factory cam with higher lift will not perform as well as as a slightly more radical aftermarket cam but you will have better low end torque and fuel economy.

 

Rings and bearings in a fairly low mileage TBI 305 is a waste of time and money, even if you get the parts cheap. Save it for use somewhere where it makes a difference.

That difference would come in the form of heads. Get some 081 castings ('87-'92 TPI 305 heads), rebuild them including new valve springs (that's where you should spend your money), then you would have something worth putting a better cam in.

There's really no hope for a stock cam. Even 1.6:1 rockers doesn't help.

The real place to spend quality $'s is the exhaust. Stock TBI exhaust is terrible.

 

About .470 to .480" lift, if you're lucky. But your best cam for a stock TBI engine is the stock LT1 cam with 1.5 rockers. It'll fit and still work ok with the stock computer programming, which will be your biggest hurdle.

See the "LT1 cam swap" sticky post in the TBI forum.