comp 980 springs and shimming

[Steve Wood]

When your car does not want to rev up to the rpm it used to...

In other words, if it used to run up to 4800 rpm and shift out of second into third, but, now it gets to 4400 rpm and does not want to increase...it's time.

Most of the cars when new, had a spring life of about 40-50,000 miles if you were lucky.

[xracerx13]

Results of Sealed power VS739R Valve Springs
Manufacturer specs installed height 1.700" @ 104 lbs.
I only bought one spring and here's what I got with the spring alone.

measured on spring tester @ 1.700" at 100 lbs.
measured on spring tester @ 1.727" at  90 lbs.

[1KWIKSIX]

Don’t forget that all new valve springs will soften (lose) some tension after the first heat cycle at start up.
I wouldn’t be surprised if those numbers posted would lose close to 10# afterwards
Just sayin

[gnonyx]

I'm gonna go buy one Sealed Power VS739R from napa today for $6 and see what I get for poundage at 1.727 on a spring tester. They are rated at 104 lbs at 1.7" so Should be around 95 - 96 lbs at 1.727"..
If that's the case I might just go with them and return these 980's. Figure after they are settled in they might drop to 92 lbs.
I keep reading bad things about the 980's and this way I don't have to shim the VS739R''s.
The turbo buick guy thats gonna install them for me usually uses K motion K700's on stock cams and they end up around 108-110 seat pounds at 1.727. I thought that was a little much.
Yes i'm a little paranoid about doing them myself.

I'm not there yet of replacing the valve springs, but do read your research on them.
The K-motion sounds good, but I just read the following, and maybe you might want to look into this for more info
https://www.corvetteforum.com/forums/c3-tech-performance/2587279-k-motion-k-700-springs-with-vortecs.html
go to #4 thread, and on the K-Motion site don't said MADE IN THE USA

[xracerx13]

I actually have done my research. I am not going with K-motion 700's cause hey end up being around 108 lbs at 1.727. So no.

I have a set of comp 980's tested for pressure and ready to go that I will be shimming .030 to get to 88-90 lbs., but wanted to experiment with one of the sealed power VS739R to see what I got on a spring compressor.

I work on my car myself only and have since 1987 but I don't have a compressor and I feel more comfortable with someone else doing them since he does them all the time and has been in the game since 1987. Also he races like I used to. He is also a gm certified mechanic but specializes in turbo buicks.

The springs do lose a little after the first heat cycle but its more like 3-5%

I think after 115k miles its time to do them....