Valve Spring Tech: CompCams 980-12

[NCTURBOS]

There has been alot of tech advise here on the boards about which valvespring to install on your car for an upgrade to the oem cam/lifters/etc... The CompCam 979-12 or 980-12 seem to have been the standard over the years. There has also been the discussion on re-installing the oem cup dampner that surrounds the spring, or not. And whether to run the internal dampner that comes in the 980-12, or not. Here is some information based off of measurements using an Intercomp digital spring tester. Thanks to Richard Clark for the use of his equipment & Patrick (SloGN) for doing the dirty work... :biggrin:

A couple givens:

The factory installed height on both GN and TTA heads, using the oem locks/retainers/valves is 1.687". If you choose to install the new springs without the oem cup dampner that surrounds the springs, which also acts to shim the springs .040", your new installed height is 1.727". The stock oem camshaft measures .393"/.408" lift, which I averaged to .400" for this "testing".

We measured (2) different CompCam 980 springs out of a brand new pack.

Spring A - Height - Spring B with internal dampner:

78 = @ 1.727" = 76.2
88.8 = @ 1.687" = 87
202 = @ 1.327" = 199.6
217.6 = @ 1.287" = 211

Spring A - Height - Spring B without internal dampner:

71 = @ 1.727" = 72.4
81 = @ 1.687" = 83.2
181.6 = @ 1.327" = 183.2
193 = @1.287" = 194.2

For comparison sake, here are what some stock oem springs with 109k miles off a TTA measured:

55.6 @ 1.727"
65.6 @ 1.687"
164.2 @ 1.327"
174.4 @ 1.287"


K.

 

[22lbChevelle]

This is a great reminder to those who have forgotten to install shims when you quit using the stock cup style dampeners. The extra 11 pounds will really help keep the lifter in proper contact with the lobe.

 

[87GN_70GS]

What are the minimum spring requirements to run a stock cam? We all know the spring specs quoted in the service manual. But, obvioulsy there are plenty of folks running around with tired original springs and it probly runs fine. I wonder if the 109k miles TTA quoted above with 55 lbs of spring force ran fine. I bet it did.

 

[A2000RICH]

There has been alot of tech advise here on the boards about which valvespring to install on your car for an upgrade to the oem cam/lifters/etc... The CompCam 979-12 or 980-12 seem to have been the standard over the years. There has also been the discussion on re-installing the oem cup dampner that surrounds the spring, or not. And whether to run the internal dampner that comes in the 980-12, or not. Here is some information based off of measurements using an Intercomp digital spring tester. Thanks to Richard Clark for the use of his equipment & Patrick (SloGN) for doing the dirty work... :biggrin:

A couple givens:

The factory installed height on both GN and TTA heads, using the oem locks/retainers/valves is 1.687". If you choose to install the new springs without the oem cup dampner that surrounds the springs, which also acts to shim the springs .040", your new installed height is 1.727". The stock oem camshaft measures .393"/.408" lift, which I averaged to .400" for this "testing".

We measured (2) different CompCam 980 springs out of a brand new pack.

Spring A - Height - Spring B with internal dampner:

78 = @ 1.727" = 76.2
88.8 = @ 1.687" = 87
202 = @ 1.327" = 199.6
217.6 = @ 1.287" = 211

Spring A - Height - Spring B without internal dampner:

71 = @ 1.727" = 72.4
81 = @ 1.687" = 83.2
181.6 = @ 1.327" = 183.2
193 = @1.287" = 194.2

For comparison sake, here are what some stock oem springs with 109k miles off a TTA measured:

55.6 @ 1.727"
65.6 @ 1.687"
164.2 @ 1.327"
174.4 @ 1.287"


K.

depending on the source of the data the stock spec for the factory springs was 74-82 @ 1.727 and 175-195 @ 1.340 --------this included the damper--------i recently tested a couple sets of NOS springs # 1249267 with damper added and they measured 77/185 @ 1.727/1.340-------the closest replacement I have found to the stock spring is the TRW VS-744 available at most parts houses-------it measures 73/185 with the GN damper added--------a good upgrade is also the GM # 10212811 which measures 83/195 with the GN damper added--------another good one is GM #3911068 which measures 77/201 without the GN damper added.................RC

 

[NCTURBOS]

I wonder if the 109k miles TTA quoted above with 55 lbs of spring force ran fine. I bet it did.

That's a big negative!! The car would pull to approx. 4400rpm and lose valve control, nose over, show knock retard. Shift to 2nd gear and the car would again pull to 4400rpm, lose valve control, nose over, show knock. Shift to 3rd... Well you get the idea.


K.

 

[MY T FAST]

i understand the all the numbers (height, force etc) but for someone looking for good, durable, replacement springs (stock cam w/zddp) that i won't have to change again for a while, what does this info tell me?? 980's With new cup installed??

sorry for being so ignernt, i'd just really love to not wipe a lobe after changing my springs

 

[gusszgs]

:biggrin: Yup!

 

[MY T FAST]

:biggrin: Yup!

thank you much! ..kinda what i figured, but doesn't hurt to ask with all the experts on here. thanks again fellas.

 

[turbo nasty]

Good info..thanx for posting.

 

[gusszgs]

thank you much! ..kinda what i figured, but doesn't hurt to ask with all the experts on here. thanks again fellas.

Wasn't try'n to a smart azz......I was agreeing with your #6 post.
I've had the the comp 980's without a cup for 2yrs now and no issues. I run a ZDDP in with the oil change every time. Motor is stock.

 

[SCOOBY DOO]

I run the 980's without the cup and pound my car at the track every Saturday and it revs to 5200 at the shift points effortlessly.

 

[MY T FAST]

Wasn't try'n to a smart azz......I was agreeing with your #6 post.
I've had the the comp 980's without a cup for 2yrs now and no issues. I run a ZDDP in with the oil change every time. Motor is stock.

i didn't assume you were being a smart azz!! sorry if i came off that way. i was just thanking you and all the other people on here who are more knowledgeable than I for sharing your information it's greatly appreciated.

 

[bison]

Properly installed 980's are fine on a stock cam as long as you're not trying to go really fast. For anyone doubting the difference with fresh properly installed springs you better think again. It's not a little difference. It's huge. If you stock cammed car with stock springs shifts at 4800 the difference may be small but if you're still on the stock cam and need a few hundred more rpm there is a huge difference in power.

 

[bison]

What are the minimum spring requirements to run a stock cam? We all know the spring specs quoted in the service manual. But, obvioulsy there are plenty of folks running around with tired original springs and it probly runs fine. I wonder if the 109k miles TTA quoted above with 55 lbs of spring force ran fine. I bet it did.

It may be fine if your car is stock but if not there is a lot of potential that wl never be realized.

 

[BMR]

Properly installed 980's are fine on a stock cam as long as you're not trying to go really fast. For anyone doubting the difference with fresh properly installed springs you better think again. It's not a little difference. It's huge. If you stock cammed car with stock springs shifts at 4800 the difference may be small but if you're still on the stock cam and need a few hundred more rpm there is a huge difference in power.

There is no exaggeration in this statement. I just changed my springs to 980s and the car just flat runs better everywhere. Its night and day at the shift points.