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Tested 2 each of: Stock 112K mile GM valve springs with cups and 2 Comp. Cams. 980's no cups.
Measured distance traveled to get three spring forces in lbs. Kinda backwards of usual tests but worked for me.
Used a calibrated and very accurate Instron machine at work.
Here's my results.
Stock Springs
Force Spring 1 Spring 2
80lb. .334" .338"
85lb. .353" .355"
90lb. .371" .372"
Comp. Cams. 980's
Force Spring 1 Spring 2
80lb. .283 .276
85lb. .300 .294
90lb. .316 .311
Springs were tested with a solid steel machined retainer with spec.s equal to the stock retainers such as shoulder on it excepting is was perfectly solid on top and perfectly flat.
I was amazed at the differences between the 2 types but was impressed with the closeness of the two samples. Woulda tested more but I only brought in a small sample in case they couldn't do it.
I'm glad I didn't use the cups with the 980's.
Measured distance traveled to get three spring forces in lbs. Kinda backwards of usual tests but worked for me.
Used a calibrated and very accurate Instron machine at work.
Here's my results.
Stock Springs
Force Spring 1 Spring 2
80lb. .334" .338"
85lb. .353" .355"
90lb. .371" .372"
Comp. Cams. 980's
Force Spring 1 Spring 2
80lb. .283 .276
85lb. .300 .294
90lb. .316 .311
Springs were tested with a solid steel machined retainer with spec.s equal to the stock retainers such as shoulder on it excepting is was perfectly solid on top and perfectly flat.
I was amazed at the differences between the 2 types but was impressed with the closeness of the two samples. Woulda tested more but I only brought in a small sample in case they couldn't do it.
I'm glad I didn't use the cups with the 980's.
