upgrade valvesprings or not?
So what exactly would the expense of changing the valve springs do for the the stock cam, make the power band flatten out from 5500 to 6000 instead of dip? I still think it's not worth the money or time. I changed the springs, one at a time with the fancy little tool and compressed air to each cylinder. It was a pain in the ***, if your gonna do springs you might as well spend your money on decent ones (Pac 1518's at least not ZO6 springs) now so you don't have to do them again later if you swap a cam . Then when you get done with all that work and there is only 5-10 hp difference between 5500-6000 rpm, I would be disappointed in the wrench time per HP gained IMHO. Thats a lota of work for that small of gain before the rev limiter. Especially for an up grade to ZO6 springs. There are alot better mods to be had for the money and time involved in a spring change on a stock cam... I'm not trying to be disrespectful, I just don't think its needed on a car with 56,000 miles.
Last edited by MPFD; Dec 28, 2009 at 09:27 AM.
The stock curve should not dip like that and won't with fresh springs. The stockers fatigue relatively quickly. Without testing the springs or running a dyno, for the OP it is hard to tell whether his springs actually need to be changed. However, the stock LS1 springs are marginal so long term if it were my motor I would freshen with some springs that will provide longer life than the stock springs. But that's just me.
Thread Starter
Launching!
iTrader: (1)
Joined: Dec 2007
Posts: 267
Likes: 0
From: Lantz, Nova Scotia, Canada
that's how i thought of it and that's why i thought maybe it's time to change springs. when my fathers 83 z-28 with 100000 on it, got his changed the car felt like it had better throttle respones and thats with a guttless cfi 305, so theres no hard runs. now with our cars we hammer this things the way they should be driven and i guess i figured over repeated abuse they would get alittle soft and need replacing.
The stock curve should not dip like that and won't with fresh springs. The stockers fatigue relatively quickly. Without testing the springs or running a dyno, for the OP it is hard to tell whether his springs actually need to be changed. However, the stock LS1 springs are marginal so long term if it were my motor I would freshen with some springs that will provide longer life than the stock springs. But that's just me.
The LS1 crate motor was originally scheduled for use in an F-body and was fresh off the assembly line. The motor came complete minus a mass air meter and starter. The street rod assembly included a dedicated wiring harness and ECU designed to allow installation of the LS1 into any pre-1976 street rod or street machine equipped with a 4L60E electronic overdrive transmission. The dedicated wiring harness was well labeled allowing easy hook up on the Westech Super Flow engine dyno. Naturally the transmission functions were not employed on the dyno.
It was a "crate" motor, how are you gonna get any fresher springs then that?
We noticed that the stock power curve had a sharp dip starting at 5500 rpm. Not being able to control the timing or fuel curves (we were limited to fuel pressure adjustments), nothing we tried could remove the dip in power. The power curve repeated time and time again, each time with the drop in power at 5,500 rpm. We don't think this is indicative of the factory curve (we've never experienced this on the chassis dyno), but we had no way of eliminating the power drop.
While I agree that the factory springs are turds, The ZO6 springs he originally posted the question about are not enough better, to be worth up grading too.
But I do agree that it is beautiful up there, I taught a class at Atlantic Cat on PEI last year, Loved it!
I just rebuilt my 241's with the yellow LS6 springs. If I had it to do over again, I wouldn't use them as there are far too many instances of them breaking. However, the heads are in storage and if they ever get re-installed I will likely swap to a different spring. I would rather throw away a set of $55 springs then have one fail down the road without warning.
Even with the new motor off of the assembly line, I will point first at valve springs unless they found an issue with the tune which it appears they didn't. It would have been helpful if they did the spring swap first, then the cam to put that to bed but they didn't. That is pretty much the exact RPM these springs show their problem on every dyno I have seen where there are issues.
Even with the new motor off of the assembly line, I will point first at valve springs unless they found an issue with the tune which it appears they didn't. It would have been helpful if they did the spring swap first, then the cam to put that to bed but they didn't. That is pretty much the exact RPM these springs show their problem on every dyno I have seen where there are issues.
