Hi all,
I had the opportunity to be able to use a near new Rimac valve spring tester for a few days (the digital version). The Top Alcohol dragster paid A$1200 for it and it is a marvelous piece of equipment. After reading someone's complaint about Comp Cam valve springs not being true to their claimed values I decided to test a new box of Comp CC-996-16 double springs that I had bought about 4-5 years ago but never used.
First of all, I was confused by the label on the box which stated that pressure at 1.15" was 366 lbs. As I was not getting anywhere near that, I called up Comp cams and asked about that; he said, oh that must be a typing error, it is supposed to be 336lbs.
Pressure at 1.7" was claimed at 115.
Pressure at 1.15" supposed to be 336
I tested each spring and the numbers were way out. Only two springs were close to claimed value, and only for open pressure. 333 and 334. All seat pressures were 120-128pounds
Open pressure values varied mostly from 328 to 334 with one being 347.
My question is, what is an acceptable tolerance for a middle quality brand of double spring like Comp Cams? I would say that these values are not very consistent with their claims. Should the buyer need to shim springs to get the desired consistent loads? I wouldn't think so.
I also tested a box of used (but near new) Trick Flow single springs (standard performance upgrade TFS-942-16)
Specs: 1.7" /1.2" 115 /285 lb
All springs except one were within 2-3 pounds in both ranges