604 crate motor valve springs breaking seats

[cool611]

Has anybody been having trouble with the valve spring seats/shims breaking... Is there a stronger seat that I can purchase so I dont break another and blow the engine...

[BTDT]

What RPM are you turning? We run a 6800 chip and tattle tale says 63-6400 all the time(and no one is running away from us). The valve train on 604's are high maintenance. We check everything every week. I have been told by a well known engine guy that anything over 6800 and you are chewing up the valve train. JMO

[cool611]

I'm running a 4/10 mile track and turned it 6700 Rpms it broke two valve shims. Just thought there would be something a little stronger they are awfully thin looking. I was under the impression that you could turn these motors 6800 rpms before they started breaking. Thanks

[brad hibbard]

the seat you are refering to is called a locating shim and yes they are a problem area

the newest version of the "legal" locators are thicker than what we have had in recent years------
that will help but not eliminate the problem

there are added harmonics on cyl's 5&7 that add even more stress to the valve train on those two cylinders

broken locators are normally found on those two cylinders but obviously can be broken in any cyl.

if your engine has had the installed height adjusted below the locator ----be very careful when replacing locators that you do not fall under minimum allowed height.

GM locating shims in the past few years have typically been .028 to .032 and if you found one that was .035 that was real good-----the latest ones are .040 to .042

as an engine builder I do not recommend RPM over 6600 but not many listen to me LOL

even at 66 you need to stay on top of your valvetrain maintenance
at 68 your maintenance program needs to be religous

hope that helps
Brad
www.race-1.com

[dynoman14]

Brad,
You point out what is very common for every SBC with standard 18436572 firing order. I worked on the spintron for almost a year on and off to find the problem and another year working on possible solutions.

I respect your professionalism and appreciate you sending me the oil pump pick-up down to Pruitts Performance last year.

I will send you a set of my Stock GM treated valve springs to run on the dyno. Next time you have a crate on there. Since 2002 I have sold over 2500 sets for 602 and 604 and have not had a single customer report a broken spring locater, broken spring or valvetrain related failure.

You should see reduced valvetrain harmonics and ability to run up to 6800-7200 without worries of valvetrain problems. I usually re-treat the springs every 10 races to keep them charged. If they go much more than that properties in the material change to the point of no re-charge. It has to do with the carbon molecules lining up like they originally started, once they take a heat set in that locaton the bonding is too strong to break and re-align.

This has been confirmed thru Non-Degrading / Intrusive Scanning Electron Microscopy. I originally tested the products in my Lab and then sent them out to 2 different Metalurgists for testing. Did not tell them what I was looking for just had the springs tested multiple times for Lattice Structure, resonant frequency and dynamic noise profile. I have never published results or the treatment processes as I have this process leased to 2 major spring companies, one in the US and one in Germany.

I currently my weekly allotment of 26 sets per week, since they have gone to cheaper spring materials it has almost doubles the treatment time so It takes me almost 12 days for cycling, where with the old German Steel it took about 6-7 days.

I use a different treatment process for intake and exhaust as they have different harmonic cycles so they will be labeled as such and they will also rate some lower than stock as the spring loses some static rate ( means not too much really ) to gain dynamic spring rate ( means nothing unless you have a valve spring dyno ) .

Consider the springs a return favor for the legal pick-up you sent me.

[DaveBauerSS6]

the seat you are refering to is called a locating shim and yes they are a problem area

the newest version of the "legal" locators are thicker than what we have had in recent years------
that will help but not eliminate the problem

there are added harmonics on cyl's 5&7 that add even more stress to the valve train on those two cylinders

broken locators are normally found on those two cylinders but obviously can be broken in any cyl.

if your engine has had the installed height adjusted below the locator ----be very careful when replacing locators that you do not fall under minimum allowed height.

GM locating shims in the past few years have typically been .028 to .032 and if you found one that was .035 that was real good-----the latest ones are .040 to .042

as an engine builder I do not recommend RPM over 6600 but not many listen to me LOL

even at 66 you need to stay on top of your valvetrain maintenance
at 68 your maintenance program needs to be religous

hope that helps
Brad
www.race-1.com
How often should the shims be checked for cracks?
Would you recommend changing them with every spring change?
Is there any way to know if one is cracked without pulling and inspecting for it? Dose it produce a miss.
Do they crack around or a line outer to inner??
Is this a concern on the 602?
Thanks, Dave

[brad hibbard]

How often should the shims be checked for cracks?
Would you recommend changing them with every spring change?
Is there any way to know if one is cracked without pulling and inspecting for it? Dose it produce a miss.
Do they crack around or a line outer to inner??
Is this a concern on the 602?
Thanks, Dave

Dave, you do not need to change them at every spring change but you do want to check for broken ones while changing springs-----simply rotate them with your finger when the spring is off and ----look for cracks where they begin to hump up and look for splits on the outer edge

until you get the feel for finding cracked ones you can use a small screwdriver and pry on them (GENTLY) to see if any cracks are present.-----but after you do a few spring changes you will be a pro at finding problem locator shims.

if there not cracked there is no reason to replace them

make sure you check installed height if there are any additional shims being used

we sell a real easy to use height mic if you don't have one for checking installed height (1.780")

602's do NOT have locating shims

Brad

[guruofdirt]

How often do you need to change valve springs on a 602 and what is legal spring pressure on em?thx

[DaveBauerSS6]

Dave, you do not need to change them at every spring change but you do want to check for broken ones while changing springs-----simply rotate them with your finger when the spring is off and ----look for cracks where they begin to hump up and look for splits on the outer edge

until you get the feel for finding cracked ones you can use a small screwdriver and pry on them (GENTLY) to see if any cracks are present.-----but after you do a few spring changes you will be a pro at finding problem locator shims.

if there not cracked there is no reason to replace them

make sure you check installed height if there are any additional shims being used

we sell a real easy to use height mic if you don't have one for checking installed height (1.780")

602's do NOT have locating shims

Brad
Thanks for the info, Dave

[brad hibbard]

How often do you need to change valve springs on a 602 and what is legal spring pressure on em?thx

Andy,
did you get my PM?

[guruofdirt]

Andy,did you get my PM?yes Thanks Brad will do this weekend

[Steve_Hendren]

One thing that is often overlooked by the weekly racer who changes his own springs, retainers, keepers, and locators, is the giant burr at the bottom of the spring locator. If the burr on the stamped steel locator is not removed, as it isn't from the factory, you will bust the locator. I've seen these burrs be as much as .015" thick. With an OEM 604, a lot of times the burr will eat into the aluminum head pretty rapidly, and not cause much a a breakage issue. However if you add hardened steel spring shims below the locator, and the locator has a thick burr....you bust the locator. So be sure to de-burr each locator before use. I have yet to see even one GM spring locator without a burr of some sort.