reagandhughes

Really could use some help here: 08 Z06 here, intake valve spring broke this week, removed with a comp cam removal tool with the head on, bore scope shows that the valve did not touch the piston. I got the car with a cam, intake manifold, intake, long tubes, MSD coil packs, aftermarket valve springs (and I think rods?), I am 95% the valves/guides have been replaces too. I do not know what cam it has or what all was done to the car though. I am trying to figure out what aftermarket valve springs are in the car so I can replace with the same one. (I need to also figure out what cam it has so I can make sure it has ok valve springs too). Looks like a conical or beehive type, the aftermarket valve seals are a light blue (just like some of the texas speed valve seals in the past few years). Top: ID .668 OD 1.05 Bottom: ID .927 OD 1.322 total uncompressed length is about 2.24". Should have pulled one of the rods when I had the rockers off but I didn't, might do this weekend. Bought some used OEM valve springs because on first glance they looked like they might be OEM but they are not (see picture, OEM on left, broken on right).

reagandhughes

The springs in the car are def harder than the OEM springs I got, also a bit shorter and wider at the ID of the base and top. Car ran great before this so I want to get the same one in there for now. I went ahead and put in the OEM valve spring just to check compression again and got 210 psi. I did this in hopes to make sure the valve was not bent at all but I know I need to get in the right spring.

Apocolipse

Wow I’m surprised to see it broken. I wonder if something is messed up in the install itself. It is definitely a conical spring and I believe only comp cams sells those right now? It will be made for a 1.8” install height for typical LS motors (not for “ls7”)

reagandhughes

Thanks for this, just spent two hours looking and it seems like the comp cams 7230-16 is very very close to what mine is, and they only sell sets for $370. Great.

double06

I would pull another spring and get it tested. Those conical comp springs can have some very high spring rates that might not be suitable for what you have there and not sure why it broke either. You may end up going back to the standard double spring that most of these LS7 hydraulic rollers aftermarket cams have. Find out what cam you have that can help. No reason to run 500 psi open when you only need 400 psi open. BTW if you have stock lifters they are not going to like 500 psi open.

grinder11

I agree. I don't know if the OP knows how MIGHTY lucky he was that he didn't drop a valve and grenade the motor!!! Anyway, I'm always running duals, for that reason. I have PAC 1905 duals in my LS7. They've been in for 8 years, 35,000 miles. They have specs of 1.800 installed height, 160lbs seat, 420lbs open. They work for me. Only problem I've had from the beginning is 1 lifter bleeds down a bit on the first start of the day. It makes no noise at idle, but around 1800rpm, it starts a clack-clacking that goes away after a couple of minutes. I'd be concerned if it was all good cold, and started clacking when up to temp!! I'm running LS7 lifters, which are probably part, if not all, of the problem.

reagandhughes

Hey gents, it was the comp cams 7230-16 valve spring. It helped to narrow my search thanks to Apocolipse's comment that it was a conical spring. grinder11, yes, very very lucky.. I need to map my cam so I know what is. Is there a simple way to turn the engine over? Due to the steering rack I can't get a wrench or socket on the harmonic balancer to turn it over. I have a dial indicator that I can measure the total thrust of the cam on the intake and exhaust. Any advice on how to spec the cam in the car and then what valve springs to put in based on the cam?

Also, with the comp cams spring in I cannot get the cylinder next to it to fire at all! I made another post on it, please check it out:
https://www.corvetteforum.com/forums...post1605251908

jayyyw

Pull the spark plugs/car in neutral and you should be able to turn the engine using the nut on the alternator.

I'd replace all the springs with a set of BTR .660 springs and titanium retainers.

Turbo6TA

I posted this in another similar thread:
_______________________________________

If you want to rotate the engine, pull the relay shown in the photo below. Then get a paper clip and bend it so you can touch the two pins shown in the other photo.

The engine will rotate without fuel pressure or spark to worry about. You can 'tap' it to any rotational position you want .. and you don't need to remove the spark plugs.

Attachment 48338997

Attachment 48338998

jayyyw

Just ordered a set of relays that have a switch built in to activate the starter without spark and fuel. "Relay Bypass"

carnutsx2

Pull the plugs, put it in gear and roll the car in the garage.

Spaceme1117

For spec'ing the cam in the car, if I were to do that, I would use a dial indicator on cylinder 1. Turn the engine over until the cam is on the base circle, place the indicator tip on the rocker arm tip above the valve stem, zero the indicator, then start slowly turning the car over. Watch for where the indicator hits maximum lift. Do that for both intake and exhaust.

Measuring cam duration would be more difficult as most cam specs list the duration between 0.050 lift on each side of the lobe. And you would need to mark the crank on the harmonic balancer to be able to have a reference as to how many degrees it is as cam duration is also listed in degrees of crank duration. Maybe someone else has a method for measuring duration.

As for a good, high quality valve spring, PAC, Cam Motion, PSI, BTR are all great springs. Comp Cams in my opinion is not the best option and seems to have a bit of a reputation for broken valve springs.

dAgent

Man, what is it with comp springs? Never heard of PSI beehive spring breaking. I was hoping this new conical design was better quality than their old beehives which were also breaking. I like the conical design, HPR likes them, I was going to run these; now I don't know.

Turbo6TA

Another quality direct 'drop-in' replacement spring for the OEM LS beehive spring is the PAC-1218 'beehive' spring. These are great springs for anyone using a cam with .600" lift or less.

OEM Beehive Single Spring
Closed Seat Pressure: . . . . . . . . 90 Lb
Open (.600" Lift) Pressure: . . . .295 Lb
__________________________________

PAC-1218 Beehive Single Spring
Closed Seat Pressure: . . . . . . . 130 Lb
Open (.600" Lift) Pressure: . . . .318 Lb

.600" Max Safe Cam Lift

$ 223 .(set of 16)

https://www.summitracing.com/parts/rsc-pac-1218-16

Spaceme1117

I used the exact springs on an LS2 GTO with a small Cam Motion cam. Excellent springs.

3X2

This is what I am using on a new crate LS7: katech kat-7523 camshaft, cam motion ps178001208 pushrods, cam motion vls100201 keepers, cam motion srs143201 retainers, cam motion sls143201 valve spring

dAgent

Never heard of a Pac beehive breaking either. What's amazing about your setup (if I remember your setup right) is the fact that 318lb open is enough pressure to control that aftermarket cam with the more aggressive lobes than stock (albeit .595 lift per cam motion) and those heavy comp steel roller rockers. How far have you revved that valvetrain?
.

Turbo6TA

My cam is Cam Motion . 220*/234* . . .585"/.585" . . 118* +4 LSA . . -9* Overlap

I spec'd the cam to have .585" lift when used with 1.8 ratio rocker arms.

At WOT, the A6 trans shifts at 6,380 rpm

dAgent

Even at .585 those are still aftermarket lobes, just goes to show the tendency is to over spring. Your shift points are low though, did you ever rev it higher to check stability? I guess not really needed with an auto.

grinder11

OP would do well to choose a dual PAC spring, imho. PSI are also very good. As for Comp, IDK what's going on there anymore, and I don't know what brand springs the OP has that broke. I do know that if he finds out for sure what springs were in there when one broke, I'd be damned if I'd reinstall the problem by buying the same springs a second time!!! I once had a set of 921 Comp duals. Never had any problems with them. They were a great spring in 2006. Now? No idea. But, again, imho, OP should go with a dual PAC or PSI setup.. Yup-I'm a guy who once broke a spring (not a Comp), and got saved by the second spring. I don't have statistics, but if the OP goes with a single spring, and it breaks again, his odds of winning the Lotto are probably better than having a single spring bail him out a second time!!