mk3cn4

iTrader: (3)

Hi, just bought a used cammed 2002 Z28 and am going to DD it, so I need to identify these valve springs #1 to make sure they are good ones and #2 because I am going to get a second identical set (hopefully) so I can be certifying/replacing one set while I drive the other set. I don't know what I'm even looking for, these don't look stock though.

UPDATE: Someone told me the ad listing the car stated "COMP" springs. Anyone confirm based on pics this could be true? Any info appreciated, going into this blind.

99 Black Bird T/A

iTrader: (4)

I don't think it's really possible to tell just looking at the pictures.

What size cam does the car have?

I would probably use a BTR Platinum Valve spring kit and freshen up the retainers, locks, valve seals & springs - if the cam is within spec's for the BTR kit.

00pooterSS

iTrader: (40)

Can't tell by looking at them but what you can tell is someone took damn good care of that motor or it is close to new.

Talk to one of the sponsors and tell them what cam you have and get the springs that work with it. You don't need to have the exact same springs, you just need springs that work with your combo.

mk3cn4

iTrader: (3)

Thank you both.

I have no idea what cam is in it, I'm going to try to dialguage the lift and get an idea. I haven't had much luck with that technique in the past with prior cars (lifter springiness was too variable), so was hoping someone would say those are comp so-and-so and I can maybe just pop one off and measure or something.

I'll do the dial gauge and also take one of the existing ones to a machine shop and see if they can "spec it out" and maybe I'll just trust the original owner spec'd the right ones to begin with and replicate what he did.

If anyone has other ideas I'd love to hear.

Thanks again guys.

G Atsma

See if you can get a long stem on a dial indicator and take a reading off the very top of a lifter. Might be tricky, but should work.

00pooterSS

iTrader: (40)

Man that sucks, so the original owner doesn't know what cam is in it?

I'd like to not over do the springs on any build but if you don't know what cam it is, you could go with the BTR .660 lift dual springs and you would cover pretty much every cam on the market. And they're a damn good price for what you get IMO.

And swap your trunions out for the bushing trunions. Bushings are the way to go now, we all know the stock ones die and the aftermarket trunion bearings are having longevity issues.

01ssreda4

iTrader: (96)

Looks like a basic 650 lift set of dual springs with titanium retainers. Should handle most cams on the market.

mk3cn4

iTrader: (3)

I didn't want to post a new thread, but had another point with this topic.

My mechanic friend has the impression that since the springs are duals I don't need to worry so much about PROACTIVELY changing them out. I know large cams are VERY HARD on springs and that's a common failure that will destroy an engine. My plan was to buy another identical set, swap once a year, and have the prior set tested at a machine shop for the next swap. Willl be doing maybe 20k miles per year.

The mechanic's assumption is that I should instead wait until one of the two springs in the dual set fail, it won't harm anything because they're duals and the valve won't drop, and just "check them" yearly looking for a problem one.

Any thoughts on this technique?

Also thank you all for your replies above, believe me it's very helpful to me.

G Atsma

Your mechanic assumes WRONG. The springs are dual to have the correct pressure for your valvetrain. True, if one breaks the valve will not drop AT LOW SPEEDS. But you will only know it broke when running at higher speeds when the one spring remaining lets the valve float, kissing the piston, and well, you know what is happening then, but too late. Your plan trumps your mechanic's assumption, in my eyes.

mk3cn4

iTrader: (3)

THANK YOU, I (and apparently he) never thought of the risk of lighter spring allowing the float. Wow, now that I read it makes me wonder why I didn't think of that LOL

Got my answer. My plan is to check every 10k and swap at 20k or yearly, whichever comes first.

First round will include trunion upgrade as mentioned above.

G Atsma

Looks like you are on the path to valvetrain righteousness.... lol
Wishing you all going well!

99 Black Bird T/A

iTrader: (4)

As said above your mechanic is wrong.

Here's my experience with dual springs long term. The springs may well hold up for a long time but the retainers can also need attention and replacement. See the link for details.


https://ls1tech.com/forums/generatio...s-9-years.html

G Atsma

99 Black Bird T/A- You mention checking the retainers. What is your take on titanium retainers for long term street use? I have heard they are not durable for that, that they get chewed up due to titanium being softer than it should be for durability.

Suncc49

I see no one has mentioned it, but you need to do the Trunnion upgrade to your rockers. Get the Chris Straub bronze kit. 159 bucks and you won't have 16 needle bearings per rocker exploding into your engine

99 Black Bird T/A

iTrader: (4)

I think the titanium retainers are OK for street as long as the valve springs & valve train gets checked ever so often. My 91 RS has titanium retainers and I plan to check springs & retainers around 15,000 miles. The 91, RS is my first direct experience with titanium retainers. If everything is good I will have the springs & retainers replaced around 30,000 miles to be safe and maybe do a cam upgrade.

I'm sure someone will probably say they are just as durable as steel and 25,000 miles or 3 years would be a reasonable point to check.

G Atsma

OK thanks! That is a fair assessment. Sounds like you would not trust them to last as well as steel retainers. I DO agree that in a high performance situation one should go over the valvetrain every 30,000 or so, even more often in higher-stressed engines. If a guy were building a 500HP DD engine, I doubt I would use titanium retainers if total valvetrain weight were not a huge concern. Everything is a tradeoff, and this looks like one of them. Thanks again!

00pooterSS

iTrader: (40)

I don't have experience in the titanium retainer durability vs steel so I can't say but I was curious about it and came across this article. It doesn't help as far as stating any results of long term testing but it does state that titanium is softer and that "these days" (the article is from 2010) FEA allows for creating steel retainers nearly as light and much stronger.. If you have any interest in scanning through it, I think it's a good read

http://www.enginebuildermag.com/2010...and-retainers/

G Atsma

Wow, THAT was a good read! Learned something AGAIN, in that it happens a lot on this forum with me. Thank you 00pooterSS!

00pooterSS

iTrader: (40)

That's what the forum is for, glad you enjoyed it! I like people that are receptive to information lol.

G Atsma

And I like it when the info is GOOD!