valve spring advise

[turbocamino1]

My 204/214 was installed with comp.980 springs 4 years ago,i think the 980's are around 90/95 seat pressure(?) Motor is quiet, runs well and i always use zddp. Lately though it seems to be nosing over at 5000 and i want a better spring. I have plenty of pump and injector and it feels like float to me. I want something better that the 980's..that wont hurt my currant cam......any advise appreciated. thanks

 

[larrym]

I've had 981's in mine for a year with no ill affect.

 

[87LtdT]

Not to disparage Larrym but I thought 981's were way to strong...never had them in my car just referring to the stiffness of that spring.

From my old data below is the advertised loads: (hope it formats correctly)

..................Load at.....Load at.....Calculated Spring Rate
...................1.700"......1.250"

980 Spring......91 lb.......229 lb...............307 lb/in
981 Spring....105 lb.......295 lb...............423 lb/in

Said another way...the 981 spring is almost 38% stiffer than the 980.

I would purchase 16 new 980's and get somebody to measure them and use the strongest 12.

Bob K

 

[larrym]

Not to disparage Larrym but I thought 981's were way to strong...never had them in my car just referring to the stiffness of that spring.

From my old data below is the advertised loads: (hope it formats correctly)

..................Load at.....Load at.....Calculated Spring Rate
...................1.700"......1.250"

980 Spring......91 lb.......229 lb...............307 lb/in
981 Spring....105 lb.......295 lb...............423 lb/in

Said another way...the 981 spring is almost 38% stiffer than the 980.

I would purchase 16 new 980's and get somebody to measure them and use the strongest 12.

Bob K

The guy I had set my heads up recommended them he said that he wouldn't put them in on a new cam install but for a cam that was already broken in he could not see them being a problem, he set the seat pressure to 100lbs and had to shim a couple springs to get them consistent. I did a search prior to having my heads ported and heard of a few guys in here that run them.
If I do end up wiping a lobe its an excuse to go to a roller cam

 

[eric_1984ttype]

The 981's are still a single spring. They are not stiff enought to cause any ill effects on a well broken in flat tappet cam using the proper oil. It would be a little different if it were a dual spring (stiff). There are plenty of SBC guys running WAY stiffer spring with flat tappet cams and they live just fine.

 

[turbocamino1]

thats what i was hoping to hear....i really dont want to kill my cam. Although i have heard/read there can be quite a variance in the comp springs when tested,new,of the shelf. Any reason a LT1 spring would be a bad choice....i think they are around 100 Lbs at the seat.

 

[streetknight]

I'd probably just put another set of 980's on it and not be worried.

Sent from my DROID2

 

[87GN_70GS]

The LT-1 and 981 are the same spring....0.192" wire diameter

 

[87LtdT]

A few years ago I obtained 980, 979 and LT1 springs (at least advertised as LT1s) and tested them all on 2 different spring testers. Also ran my used stock springs that had about 35k miles on them.

Will be glad to send the excel spreadsheet showing the raw data and summary of them all.

Not pointedly trying to disagree that the LT1 and 981's are the same spring but i will point out that just because the wire is the same diameter does not mean they are the same spring. The material they are made from and their heat treatment process are also big players in spring stiffness and life.

Bob K

 

[Kip]

Any reason a LT1 spring would be a bad choice....i think they are around 100 Lbs at the seat.

I have done alot of spring testing over the years and can tell you that a "LT1
spring" is a pretty generic term. I have seen as much as 25 lbs of seat pressure from one advertised LT1 spring to another companys LT1 spring.


Hope this helps, Kip

 

[JP112_89]

LT1 Springs ~ 105# Seat Pressure 3927142

 

[turbocamino1]

now,it seems there are 2 concerns...too much seat pressure and overall consistant quality. I can locate a spring tester, but i would like to only go through this once. if comps are inconsistant like i have read...and this is from someone in our community you all trust very much...(D.B.) he has personally tested box after box and now wont use comp springs. so...draw your own conclusion. I see Sealed Power makes a series for our cars; VS677 and VS1615 but i dont know the breakdown on the seat pressure or heights.

 

[87LtdT]

my history with these springs is about 10 years ago...

At the time Peterson Spring made the 979, 980 & 981 springs. Comp Cams does not make any springs...they buy them from companies that do. Again, back then I had an engineer friend who I used to work with who had left our company to go to Peterson Spring. He told me at the time that the 979 springs were made from a lesser grade of steel that was not able to be heat treated in the manner they should be treated, and that they were made at one of their inferior facilities... The 980 and 981 springs were made from superior grades of steel and heat treated as they should be.

He could not explain the wide variation I found in the 980's...and the Comp Cams guy disputed this same data telling me that they test all "their" springs but had no details on how...typical sales BS. Again at the time I ended up talking to Scooter (part owner) who did not dispute the data and offered to trade my 980's that I had bought from him for a much more expensive set of 981's....I declined.

Again my recommendation would be to buy a set of 16 980's and pick the 12 that are closest together. Use the "cup" found on the stock springs and that will increase the loading by about 9 lbs over not using the "cup"...it just acts as a shim about .030" thick.

And for clarity purposes...the LT1's I tested I bought from a vendor at the Nationals...they were all in a single clear plastic bag marked LT1's...could be anything.

Bob

 

[streetknight]

If you leave the cup, should you remove the dampner that comes inside the spring?

Sent from my DROID2

 

[turbocamino1]

my history with these springs is about 10 years ago..

Again my recommendation would be to buy a set of 16 980's and pick the 12 that are closest together. Use the "cup" found on the stock springs and that will increase the loading by about 9 lbs over not using the "cup"...it just acts as a shim about .030" thick.

I really appreciate your info. I cant help but to think though,if there CAN be such a varience ,what does that say for their overall quality and more importantly, longevity?

 

[87LtdT]

Yes...true in a general sense but we aren't talking about massive differences...and spring breakage in our application is a rare event so wouldn't worry about that.

The force exerted by the springs when compressed to 1.25" was:
979: 174-184 lbs with standard deviation of 2.40 lb (16 pcs)...throw out the single 174 spring and the range was 179-184 w/std dev of 1.71
980: 193-199 with st dev of 1.56 (16 pcs)...throw out the single 193 and range was 195-199 w/ std dev of 1.2
LT1: 240-253 (12 pcs) w/std dev of 3.77
Original Stock: 170-180 (12 pcs) w/std dev 3.12

Standard deviation is a measure of variation within a group of parts...the bigger the number the larger the variation...so the smaller the number the better. It is a key indicator of a manufacturers ability to produce the same part over and over.

Interesting to see that the 35k mile stock springs had a lower std dev than the brand new "LT1s" which were obviously a low quality spring and very doubtful a genuine GM spring.

By the time I threw out 4 of the 980 springs I installed 12 that had a range of 196-199 w/std dev of 1.19.

I noticed this all took place in Aug-Sep of 2000.

Bob

 

[87LtdT]

Streetknight...yes leave the dampner inside the spring. I don't have any data but I measured a spring or two without the dampner "just to see" and as I recall there was very little difference in loading.

The cup is about .030" thick and I'm unsure of it's original purpose other than to hold the spring in place. But using it compresses the spring an additional .030" and ups the entire force (aka spring pressure) the spring exert regardless of how much they are compressed.

Bob

 

[Paul Lohr]

I have tried springs from comp cams, some generic ones, crane, crower, edelbrock - they all had issues with pressure variance. It sure would be nice to have more uniform spring pressures.

If valve float is the issue, what about switching to titanium retainers? You might pickup a couple hundred RPMs on valve float and a little power.

 

[SS/GN]

I found the 981 set up with stock retainers at 97 lbs at installed height,.These springs will "settle" at around 87lbs in a few miles

Kevin

 

[87LtdT]

Kevin...that is good info. But my worry is the spring rate of the 981 is about 38% larger than the 980...so while the 981 closed valve force (aka seat pressure) isn't a "lot" higher than 980's the force imparted on the cam lobe to open the valve is still 38% larger than the 980's (because the spring rate of the 980 is 307 lb-in & 981 is 423 lb-in). Of course the valve opening event is where the cam lobe can be damaged.

Until I'm convinced I need a stiffer spring to close the valve faster I don't think bigger is better and 980's are good enough for me

Bob K