valve float with comp XE-R lobes
valve float with comp XE-R lobes I am getting valve float over 6k. I just swapped my LS4 oil pump back to a stock Z06 one. I was seeing over 140psi at WOT. Now I max out around 75. I thought the high oil pressure was over pumping up the lifters causing the valves to unseat and float. The car does run much better but still valve floats above 6k. I think it might be the springs that were installed on the heads. Both were bought assembled used but had just comed back from CNC heads in St.pete FL. He is a very reputable head builder and I am sure they were installed propperly. I am not sure if they got damaged at all when I was running with the super high oil pressure. We plan to tear the valve train down to inspect. What I need to know is, even if they check out fine, are these cranes under rated for my setup. I want to be able to spin the motor to 7k without valve float. The specs on the springs seems a little low. I also am not sure what the installed height measurement is. If it is standard(1.8), will shimming be enough or are firmer springs in order.
My cam is a comp xer grind 232/236 .595/.601 114lsa. The springs are crane duals according to the previous owner(144832's I believe). He had a much more aggresive cam than this so I figured they would be fine for my cam. I am also running Jesel sportsman series shaft mount rockers. They are stock 1.7 ratio. I also have hardened 7.450 pushrods which give me .060 preload on the caddy lifters. I am considering the new patriot extremes or the crane 144833's. Since I already have the locks and such, I can just buy the springs.
Any info on the standard crane springs with this cam would be great. Plus any other recommendations.
Mike
My cam is a comp xer grind 232/236 .595/.601 114lsa. The springs are crane duals according to the previous owner(144832's I believe). He had a much more aggresive cam than this so I figured they would be fine for my cam. I am also running Jesel sportsman series shaft mount rockers. They are stock 1.7 ratio. I also have hardened 7.450 pushrods which give me .060 preload on the caddy lifters. I am considering the new patriot extremes or the crane 144833's. Since I already have the locks and such, I can just buy the springs.
Any info on the standard crane springs with this cam would be great. Plus any other recommendations.
Mike
How long did the previous owner use the springs? If he had a very aggressive cam maybe the springs are tired and lost seat pressure. I would check the springs against Cranes specs to see if they are worn out.
TECH Enthusiast
Joined: Sep 2003
Posts: 730
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Use a .030 shim with them or even if you get the newer 833's.
Springs in general are a wear item and are like buying used brake pads.
The hardened seats they come with will net you a 1.77 installed height as of right now. It will be 1.74 with the shims.
Springs in general are a wear item and are like buying used brake pads.
The hardened seats they come with will net you a 1.77 installed height as of right now. It will be 1.74 with the shims.
Crane 832's have a very low seat pressure and are designed to be shimmed by the installer. If you didn't shim them at all, your seat pressure is in the neighborhood of 122 lbs. You need to shim them, but I agree, go with the 833's and replace them. That will cure the problem and if you have floated them a few times their future is quetionable anyhow.
Originally Posted by vettenuts
Crane 832's have a very low seat pressure and are designed to be shimmed by the installer. If you didn't shim them at all, your seat pressure is in the neighborhood of 122 lbs. You need to shim them, but I agree, go with the 833's and replace them. That will cure the problem and if you have floated them a few times their future is quetionable anyhow.
Teching In
Joined: Jul 2006
Posts: 26
Likes: 0
From: Baton Rouge, Louisiana
I put shaft mounts on my ls6 after head cam swap and had valve float using the patriot gold duals, took the shaft moungt off and put the stock rockers back on and no float. Most shaft mounts are too heavy on the nose and cause the valves to float.
DD
DD
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Originally Posted by Dandy Don
I put shaft mounts on my ls6 after head cam swap and had valve float using the patriot gold duals, took the shaft moungt off and put the stock rockers back on and no float. Most shaft mounts are too heavy on the nose and cause the valves to float.
DD
DD
Mike
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I wouldn't put 832's on any aggressive lobes. Stick with what works, the Patriot line. While aftermarket rockers are stronger than the stock ones, they tend to be heavier. More weight in the valvetrain, on the spring side of the rocker, will add to floating issues. This in turn means you need to run a spring with more pressure than you normally would because your now trying to control the aggressive cam lobes and added weight.
Trade the cost, the 833's will work with the seats and retainers you have now. If you switch you will need to pull the seats and hence the valve seals. The 833's are comparable to the Comp 921's, so if you can get bare springs you can re-use all your current parts and they will set up on the seat much higher, but best to check installed height and run the numbers.
Originally Posted by black_z
Why not run 918's?
And if your replacing rockers, look into having your stockers rebuilt & the bearings reinforced by Harland Sharp. Its only $250+shipping & you get to keep stock function with aftermarket performance. Thats what I'm doin after lookin around at different places & pricing.
Originally Posted by BIG_MIKE2005
And if your replacing rockers, look into having your stockers rebuilt & the bearings reinforced by Harland Sharp. Its only $250+shipping & you get to keep stock function with aftermarket performance. Thats what I'm doin after lookin around at different places & pricing.
You have to call Harland Sharp or go to their website. I found the website & called them. They explained what all they do & told me it was $250+shipping which was gonna probably be another $15. But you also have to pay shipping there. The extra shipping they charge is to ship them back to you.
Thanks for all the info. I think I am going to get the 833's. I plan to do a leak test tomorrow to make sure all the valves are good. I want to make sure I didn't kiss a piston with all that has gone on. I think i'll do a compression test as well just to have those #'s for reference.
After the leak test I will pull the springs and get the measurement for my seats and locks and such. Vinci said that if all is good then yes the springs will bolt back in and I can reuse all my existing hardware. This will make life much easier.
As for the CAM, it is nice but I have not been able to go past 6k with it. I did all this at the same time so no real experience with it. It is very nice on the street so far but my car only ways 2750lbs. I picked the cam to give me more mid-top end since my car is so light and I am limited to a 285 size tire out back. Figured get the car going then build power. No sense in roasting the tires everytime I go from a dig.
Mike
After the leak test I will pull the springs and get the measurement for my seats and locks and such. Vinci said that if all is good then yes the springs will bolt back in and I can reuse all my existing hardware. This will make life much easier.
As for the CAM, it is nice but I have not been able to go past 6k with it. I did all this at the same time so no real experience with it. It is very nice on the street so far but my car only ways 2750lbs. I picked the cam to give me more mid-top end since my car is so light and I am limited to a 285 size tire out back. Figured get the car going then build power. No sense in roasting the tires everytime I go from a dig.
Mike
Originally Posted by GuitsBoy
Just shim them. They need it. Why is this not more well known??? I really wish the dealers would warn customers about this.
This brings up the real question, how much psi do I need. From what you guys are saying, the problem may be the Jesel's being heavier than the stock rockers. I would like the keep the Jesel's so what # should I shoot for. If I use the crane seats and install the 833 springs around 1.750, I will have 157# at the seat. Is this too much?
Mike