89FRMLA350

What would be the most amount of lift on a cam i could use with the stock springs. I really dont want to break one and drop a valve or some ungodly thing like that. If anyone knows or can help me out id appreciate it

BronYrAur

iTrader: (1)

For a 15 year old car that will most likely have some pretty good mileage on the clock as I'm assuming your car does, I would get new valve springs if I put a new cam in no matter what the specs on the cam. Springs are not very expensive and are great insurance, pick up a set of Z28 springs or something, you can find them very cheap.

25THRSS

Ive heard the stock springs can take over .450 lift.

Frik92RS

While we're on the topic is it worth it to go with expensive aftermarket springs or will z28 springs do the job for something like a lt4/zz4 cam?

BronYrAur

iTrader: (1)

I think the z28 springs are only rated for up to .490 lift or something so you wouldn't want to use a ZZ4 cam with them I wouldn't use any cam thats over .490 lift or even a cam that's close to .490 lift just for insurance.

Dewey316

http://www.sdpc2000.com/cart.asp?act...2060&pid=81626

i ordered these to use on my upcoming swap, total was $54 after shipping. they are good to .550 and they had just about the same seat pressure as the comp springs that comp recommended for my cam.

and they are 1.25" springs, so no machining the seats!

Beast5spdGTA

I wouldn't go with a cam over .470" lift with any springs on the stock heads. I know on my TPI car a little ridge was formed on the groove in the valve, I'm assuming from retainer to valve guide contact while running ~.490" lift.

Otherwise I'd just get some z28 springs or LT4 whatever, should be alright for a mild cam.

brodyscamaro

I wouldn't change the cam at all without changing valve springs.

V8Astro Captain

iTrader: (1)

Yeah, in fact, I would feel better changing the OEM springs without even doing the cam swap.

I don't think you want to run more than .500" lift with 1.25" springs. I've never run them that long on the street, but it just doesn't seem like a good idea to twist a tiny valve spring that far.

TransAmTBI

isnt it hard to change the springs if your doing the cam swap with the heads still on the car???
the effort doesnt seem worth it
i as well am doing a lt1 cam swap

costill91Z

to change the springs with the heads still one the car, you need an air compressor, and a threaded "blow gun" attachment that will fit in the spark plug hole to keep the valve from dropping

TransAmTBI

why does that sound not too easy! i may not have these effeciencies.. but I have heard about putting the picton at the top of the cylinder ofsomething like that??

anyone?

V8Astro Captain

iTrader: (1)

I've heard of GM springs that were 45 #'s at seat pressure.

Try it with the stock springs, it will prolly turn into a big sh@tty mess.

Turn the piston to TDC, then charge the cyl full of air. It takes a bit to keep the valve up, but with the piston at TDC you shouldn't have to worry about the valve dropping. You need enuf pressure to keep the valve up but not so much that it spins the engine over.

Just go one cyl at a time. I usually follow the firing order.