Valve spring change

D

DavzGN

Well-Known Member
Joined
May 28, 2001
I am finally changing out my valve springs. I bought some springs off eBay a couple years ago that were supposed to be comp cam 980 springs. I just had them tested and they tested out at 105 at 1.725 and around 265 at 1.340. looking at the comp cam specs they seem like they may be 981 springs. Should I risk running these or order some 980s to be safe?

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New springs are cheap vs risking something bad happening . Bout $ 60 bucks or so ? Its your money but if it was my car new springs would be going on . Just my 2 Cents
 
I ran 981 for awhile you have to think how much spring you are losing when in boost . I can tell you there is more pressure then your boost psi working directly against your spring psi
 
DavzGN said:
I am finally changing out my valve springs. I bought some springs off eBay a couple years ago that were supposed to be comp cam 980 springs. I just had them tested and they tested out at 105 at 1.725 and around 265 at 1.340. looking at the comp cam specs they seem like they may be 981 springs. Should I risk running these or order some 980s to be safe?

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Click to expand...


Stock setup on the car .. what mods ?
 
Mostly stock, SD2 with flex fuel, upgraded pump, 80lb injectors

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You can go with Comp Cam 979-12. That's what I did. From what I read over & over, They are closest seat pressure to stock just slightly higher...will work fine reusing the stock cups...That I think has been tested or used before. Or go straight to GM. I'm doing this in the summer, along with the timing chain(new NOS original set). I wouldn't trust anything off ebay, especially if it's inside parts like that. Go to GM or someone that deals with those parts with a stock camshaft
 
Last edited:
Most don't run near enuf valve spring pressure. 135 lbs on my build below with a flat tappet 212/212.
 
SCOOBY DOO said:
Most don't run near enuf valve spring pressure. 135 lbs on my build below with a flat tappet 212/212.
Click to expand...


and some that do wind up with flat lobes ...

Run as much spring pressure as you need .. this is an area that more is not better .

if its a stock cam , unopened motor, stock turbo .. there isn't any point in putting springs over 105#'s in
its also important to make sure the springs are matched .. ive seen sets from big vendors come with springs that are in left field pressure wise due to lack of quality control..
also todays oils are different in viscosity and additives ... be careful with spring pressures
 
980's and 981's soften quickly in race conditions. I was tired of changing them 3-4 times a season. Lobes and lifters were recently checked...all's well. Stock spring pressures are fine for daily drivers and the occasional track hit. Racing every weekend...is a different story.
 
SCOOBY DOO said:
980's and 981's soften quickly in race conditions. I was tired of changing them 3-4 times a season. Lobes and lifters were recently checked...all's well. Stock spring pressures are fine for daily drivers and the occasional track hit. Racing every weekend...is a different story.
Click to expand...


That's Comp quality for ya .. Try some PAC's .. doubt you will be replacing those 3-4 a season
 
turbo89 said:
and some that do wind up with flat lobes ...

Run as much spring pressure as you need .. this is an area that more is not better .

if its a stock cam , unopened motor, stock turbo .. there isn't any point in putting springs over 105#'s in
its also important to make sure the springs are matched .. ive seen sets from big vendors come with springs that are in left field pressure wise due to lack of quality control..
also todays oils are different in viscosity and additives ... be careful with spring pressures
Click to expand...
I went into the 10s with a stock cam on 100lb valve springs:D
 
I have some 980s being delivered tomorrow. Hopefully they are sufficient for the street. I was afraid that the 105lb springs that were supposed to be used 980s would be too much. I had a couple of the old springs tested and there were 65lbs.

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