As the title implies this is a "tech" post about the spring life of solid roller setups. I will refrain from mentioning drag racing as this may get shot over to general...

Anyways, I was "tech-racing" my car this last weekend and I noticed the motor was breaking up around 7000rpm, just slightly, but enough that I noticed it. I found that one of the springs was down 15lbs on the seat, but a whopping 50lbs at the open pressure.

Old Spring:

150lbs @ 1.850
390lbs @ 1.250

New Spring:

165lbs @ 1.850
440lbs @ 1.250

I went ahead and replaced the springs today, they are a Comp 977-16 dual spring with damper.

I had ~60 drag strip passes and 5000+ hard street miles on these springs so I think they did pretty good considering the conditions.

My tech question is: What is a reasonable amount of time one can expect from these springs?

My tech suggestions is that those running higher spring pressures should check their springs out on an annual basis. These springs are one and a half years old, and did end up sitting for ~3-4 months over this time. I assume this time sitting with the spring open helped accelerate the process.

Anyways, I put new springs on today along with new valve seals: For you AFR guys who are having oil problems I am using the late model GM viton valve guide seals and have no oil consumption problems, I just figured it would be cheap to replace them while it was apart.

I will be going tech-racing this weekend and will post results ASAP.

 

good luck at the track!!

 

Roller cams especially solid rollers are hard on valve train part. That being said CC developed the XR line as a street/strip cam and should be easier on parts including springs. I expect mine to last longer than 5000 miles but would not suprise me if they didn't they will always lose a little. I always loosen mine off over the winter I am running the 929 springs which allow about .650" lift so I could run the 1.6 ratio rockers.

977's are 155# closed and 419# open, no ?

 

Motorhead: Yes, those are the numbers on box, but no these are 165/440, I was told that they usually are a little higher out of the box. No complaints here.

 

The XR line of roller cams is the most aggresive lobe on any "street" cam Comp makes.

If you run a roller cam.... they eat springs. 5000 miles is very good. Make sure you check them regularly for lash and broken springs. A forum buddy of ours just checked his and found two broken retainers.

 

Thanks, I have been keeping an eye on things and the lash did not change over 4 months and nearly 4000 miles. I am running titanium retainers and they looked OK. The damper spring, however, did leave an imprint in the retainer. The shims also were in good shape, as were the locks.

I think I am going to pull the motor this fall and re-ring and bearing it as it will have ~16,000 miles on the shortblock by then. I will probably replace the roller lifters at the same time.

 

Actually over the years, I've had pretty decent luck with valve springs on my big blocks.

When I ran flat tappets in my 427 and using basic $100 sets of springs, steel retainers and stock type valves, I found that after about a year of street driving and racing (lots of test sessions!) the car would mysteriously slow down a tenth or two and 1-2 mph. Change the springs and bingo...back in business! Yet it never popped, banged or spit..it just didn't seem to pull as well at top end.

My first roller cam (.725 lift) used a set of Isky "NASCAR" springs. They were only around $150 a set, but I ran them for 2-3 years with that cam, and then used them again when I dropped down to a .623 lift street roller. When I checked pressure, they had only lost around 10 psi when I put them on the smaller roller. In fact I used +.050 retainers to get pressure down some to match new cam. They ran 3 more years until I sold the heads with them on them.

My Brodix heads came with "who knows" springs. Maybe Manleys? Comp? Anyway, I ran them for several years with a .675 lift cam and they were still fine when I pulled them to check.

After that I went to a set of K-Motion's and titanium retainers with the new .731 lift cams. They have a couple of years of racing and street drivig on them (to BG and back!) They still check out fine. Almost no loss of pressure.

I think even the 'small" 1.55" big block springs helps the issue by not working it as hard as comapred to a smallblock 1.46. 1.625's are even better if you can get reasonable pressures. I like running a little more spring than required and backing off installed height a little etc to allow it to not be worked as hard.


JIM

 

What is your max net lift? You listed only .600 lift springs. The hotter a spring runs the faster it fatigues. That's why I run .750 lift springs and only lift them in the low .600's

My springs are also something like 180# closed and 560# open at .640 inch. With my valve weight and extreem ramp cam new they should be good to 8000 rpm without float. That way when they age and loose spring pressure you still have a 7500+ rpm safety margin.

 

So why don't we hear about factory roller cam engines eating springs?

 

But what are you comparing them to ? You have to compare apples to apples here and that means you have to compare solid rollers to solid rollers, so tell us which solid rollers that Comp Cams makes are easier on springs and if it is a straight up design maybe I will try it next time since I now have a good flowing exhaust

 

Motorhead: Check the comp catalouge and compare the cams
at .050 and at .200 If a cam has the same duration at .050 as another but more at .200 then it is more "intense." That was my only point. The XR lobe is a very intense srteet lobe.

Take a look at the High Energy series of lobes, much more gentle than the XR.

For example one HE lobe is 262 at .050 and only 176 at .200

One XR lobe is .260 at .050 and 181 at .200

 

Because H-rollers are very mild lift ramps, low total lift, and use lighter weight springs.

They don't look like this for a cam lobe profile!

 

I agree with you about the XR series in the flat tappet designs, my point is that they made the XR solid roller cams so you could run them on the street with cast/stock distrubutor gear and lift duration ratio that would make your valve train survive on the street alot longer than any of there other solid roller cams with the exception possibly of the Magnum series. The solid roller by nature is going to have an aggressive ramp as you can see in gkull's post, actually I am suprised the lifter stays on the lobe at high RPM