Hey guys! So I am working on my LB9 305 motor out of an '86 IROC and I have a few questions for you guys about cams and other things.

To start with the basics, how much lift can i get out of a cam on a stock motor? I was looking at a cam with .465 intake and .488 exhaust. Can my 305 handle that? Is the lift too much?

Also, how long should my pushrods be? The springs are double-spring ones, i'm pretty sure that is not stock but they appear to be stock height, but who knows? The previous owner put them in. (along with a supposedly notorious 327 cam 3863151 ) Are these springs enough for that much lift?

Sorry for any dumb questions. If I mis-stated something feel free to correct me. I am still young and this is the second motor I have ever worked on (dodge 440 was first) Everyone has to start somewhere, huh?

 

Bump

Anybody? I need help. I really want to get this motor done.

Thanks guys.

 

About the .460-.480" range is tops for factory setup. Only way to know for sure is to measure.

If you haven't done anything to the valve train (stock cam, stock pressed in studs, stock heads), then your pushrods are stock length.

Impossible to know if a spring is too much or not enough without a part number. Best bet is to buy and install the recommended springs for whatever cam you get.

 

Lift is the least of your worries. TPI is fussy about cams, so look for one that is computer-compatible. And, keep lift under .480" if you don't want to pull the heads (although that wouldn't be a bad idea).

 

Alright, thanks for the input. The heads are already off, motor sitting in garage ready to be worked on, I am painting motor, doing gaskets, etc. The last owner did a very horrible job at doing gaskets. What do you recommend head-wise? I definately want to get around .480 I may get a professional valve job to accomidate for any extra air flow needed.

 

Oh, also, what do stock pistons look like? I think the motor already has high performance(lol) pistons in it

 

Stock pistons are flat tops with 4 valve reliefs.

If the heads are off, have the top of the valve guides cut for positive-type stem seals. Not only will you have superior seals, the valve will have more travel - like .550" easily with safety clearance. And, a little bowl clean-up helps a lot on those heads. You might also want to consider doing something about the press-in rocker studs, either pin them, or have them replaced with screw-in studs. With those things, the stock heads will be fine.

 

If I get the heads cut for the positive stem seals, what will I have to buy to make it work? Im not sure what it is. It sounds like something I need to do... How much would it cost to get done? For reference, it will cost me 120 to have the heads dipped and do the valve job.

 

The machine shop should have the tool to cut the guides. Labor probably $50 or so, since they'll already have the heads apart, but ask them, anyway. Seals are a couple of bucks a piece.