Question about replacing heads on LS2
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Question about replacing heads on LS2
I had a cam installed a few years ago when I first bought the car and I cannot for the life of me remember the specs of the cam. I know it was a pretty aggressive cam at the time. Well, I am pulling apart the motor as there seems to be either a bent valve or busted spring and want to replace the heads with possibly a set of LS6 heads and was reading somewhere that I need to know the specs of my cam so that I get the correct type of valves. Is this true? If it is, what do I do since I don't remember the specs of the cam? Any info would be appreciated!
Racer
Joined: Jun 2009
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From: Houston Texas
ls6 heads are the same casting as ls2 heads. I would pull the cam and run the numbers to make sure. You may be able to use a dial indicator on a lifter to find out what the lift of the cam is.
Last edited by Schoolteacher; Oct 3, 2011 at 08:46 AM.
Track Junky
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From: Orlando Area
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I agree on both counts. LS6 and LS2 heads are the same except for the valve material - both 243 castings. That's the LS2 head was born...
The only sure fire way to get accurats specs on the cam is to remove and measure w/ cam doctor or similar. With a dial indicator you could get lift but not degrees or LSA, both of which can affect PTV clearance.
The only sure fire way to get accurats specs on the cam is to remove and measure w/ cam doctor or similar. With a dial indicator you could get lift but not degrees or LSA, both of which can affect PTV clearance.
Drifting
Joined: May 2005
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From: Avon Indiana
St. Jude Donor '09
I bet the only reason you need cam specs is to properly match the valve SPRINGS... not the valves... unless the springs are so stiff that they dont want you to use hollow valves
Last edited by stanger383; Oct 4, 2011 at 07:44 AM.
Track Junky
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From: Orlando Area
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And to ensure no PTV issues. I have Spin's 230/234 114+2 cam and I'm below the recommended 0.080 PTV on the intake (I'm at 0.065) with Cometic 0.040 head gaskets. This cam is relatively mild so anything kore aggressive could get you into trouble. Good thought on the hollow valve thing as well.
Safety Car
Joined: Jul 2001
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From: Detroit's West Side MI
Is there a general rule of thumb as to how much lift is "safe" to prevent float with a stock LS2 valvetrain? What about the LS6 valvetrain?
Is the only difference in the LS2 vs LS6 heads the sodium filled valves? I see LS6 heads go for a LOT of money due to the mystique of the C5Z, but since I will be replacing the valvetrain anyway on my build it sounds like it doesn't matter to me as long as I get a 243 head.
Thanks!
Is the only difference in the LS2 vs LS6 heads the sodium filled valves? I see LS6 heads go for a LOT of money due to the mystique of the C5Z, but since I will be replacing the valvetrain anyway on my build it sounds like it doesn't matter to me as long as I get a 243 head.
Thanks!
Track Junky
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From: Orlando Area
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Scary, I think the stock springs are rated to 0.550 lift. Can somebody back me up on that? If so, that wouldn't leave you much room for a cam at all. Valve float is a function of a spring's ability to maintain contact with the rocker arm at high RPM ad the lifter to stay in contact with the cam lobe. I have read that the stock LS2 lifters are stable to 6800+ rpm, but I wouldn't do that (or any internal engine mods for that matter) without replacing the springs. I would also seriously consider upgrading the rocker trunion bearings with the Comp Cam kit. Stock lifter needle bearings have about 0.030-0.040 slop in them when unloaded. That could lead to valvetrain instability at high RPM as well. For me, it was worth the $130 insurance policy - only takes about an hour to swap the bearings once out of the car.
I believe that the sodium valves are in fact the only major difference. Ported 243 castings cam make great power, especially when compared dollar for dollar with the big boys like TF and AFR. HC Mechanic made 525 rwhp with them and Leavin U is in the 505-510 range. I'm sure there are plenty over the 500 rwhp mark with ported 243's.
Does that answer all of your questions?
I believe that the sodium valves are in fact the only major difference. Ported 243 castings cam make great power, especially when compared dollar for dollar with the big boys like TF and AFR. HC Mechanic made 525 rwhp with them and Leavin U is in the 505-510 range. I'm sure there are plenty over the 500 rwhp mark with ported 243's.
Does that answer all of your questions?
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Thanks for all the responses. I'm currently in the process of breaking my entire car down. I believe I have a collapsed lifter so since I have everything torn apart, I figured I would put some new heads on. I really wish I knew the specs of the cam! Would there be some sort of identifying number on the cam? I believe it was a Comp Cam. If there is no identifying number, how exactly would I go about 'running the specs' on the cam? I know it was a pretty big came when I got it at the time. I was thinking of getting the LS9 heads as they aren't too terribly expensive, I just don't know what kind of power they would make. My car dyno'd at 426rwhp a few months ago. Should I use the springs that come with them or the springs that were installed when I had my cam installed? I assume I would just re-use my existing springs since they have been working fine.
Sorry for all the questions, but I need these answered since I'm to the point where I'm about ready to start ordering the stuff for the car. Just want to make sure I do it right. TIA!
Sorry for all the questions, but I need these answered since I'm to the point where I'm about ready to start ordering the stuff for the car. Just want to make sure I do it right. TIA!
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Track Junky
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From: Orlando Area
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If you can get an identifying number on he cam, Comp may be able to helP you out. Only other way would be to remove and send to a shop that has a cam doctor. They can measure exact specs that way.
Don't know much about the LS9 heads, but you could CNC the stock 243's and make good power that way. Several choices there - TEA, Advanced Induction are a couple for about $1000. If your sprigs have 10k miles or more on them, you might want to considerchanging just for peace of mind. I have read that aftermarket springs last 15-20k miles with an aftermarket cam. That all depends on driving habits and cam lift and lobe profile.
Don't know much about the LS9 heads, but you could CNC the stock 243's and make good power that way. Several choices there - TEA, Advanced Induction are a couple for about $1000. If your sprigs have 10k miles or more on them, you might want to considerchanging just for peace of mind. I have read that aftermarket springs last 15-20k miles with an aftermarket cam. That all depends on driving habits and cam lift and lobe profile.
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Oh wow, 15-20k miles? I did not know that. lol, I've had the cam installed for about 60-70k miles so I might as well replace the springs while I'm at it. If thats the case I will definately need to figure out the specs of the cam so I can order the correct valve spring replacements. I'll see about contacting Comp to see if there is any type of identifying number on the cam.
Melting Slicks
Joined: Jun 2005
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From: Sicamous BC
I think with some measuring you can get a very good idea what cam you. You are going to need a dial gauge & a degree wheel. Easy to get the lift, ICL & the LSA. From there I'm guessing you should be able a reasonable accurate .006 to .200, then you could probably make a reasonable lobe identification. You would need to do that for both exhaust & intake lobes as some cams are ground differently for exhaust & intake.
BTW I also have a DSOM Vert with Cashmere interior & top. My wife won't let me touch it based on the results from C5 LS3 stroker project
BTW I also have a DSOM Vert with Cashmere interior & top. My wife won't let me touch it based on the results from C5 LS3 stroker project
Race Director
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From: God's Country, ID
Thanks for all the responses. I'm currently in the process of breaking my entire car down. I believe I have a collapsed lifter so since I have everything torn apart, I figured I would put some new heads on. I really wish I knew the specs of the cam! Would there be some sort of identifying number on the cam? I believe it was a Comp Cam. If there is no identifying number, how exactly would I go about 'running the specs' on the cam? I know it was a pretty big came when I got it at the time. I was thinking of getting the LS9 heads as they aren't too terribly expensive, I just don't know what kind of power they would make. My car dyno'd at 426rwhp a few months ago. Should I use the springs that come with them or the springs that were installed when I had my cam installed? I assume I would just re-use my existing springs since they have been working fine.
Sorry for all the questions, but I need these answered since I'm to the point where I'm about ready to start ordering the stuff for the car. Just want to make sure I do it right. TIA!
Sorry for all the questions, but I need these answered since I'm to the point where I'm about ready to start ordering the stuff for the car. Just want to make sure I do it right. TIA!
If you are lucky, the lifter didn't mushroom (scoring the cam lobe in the preocess) and you can get the lifter out without pulling the cam.
If you do have to pull the cam to get the specs or replace, you can send it in and it can be measured and a new cam ground to close/same specs.
I sent my 243's in to WCCH and had Richard work his magic. They do some sweet work, know thier stuff, and have been around a long time.
If the cam is trashed, I have a cam manufacturer local to me that does all the grinds for the major cam distributors. I paid $250 for him to measure mine and custom grind brand new cam to the specs I wanted. He's been in business for 30 yrs. Basically you are just cutting out the middle man. Pm me and I can forward you his info.
Track Junky
Joined: Jun 2007
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From: Orlando Area
Tech Contributor
Oh wow, 15-20k miles? I did not know that. lol, I've had the cam installed for about 60-70k miles so I might as well replace the springs while I'm at it. If thats the case I will definately need to figure out the specs of the cam so I can order the correct valve spring replacements. I'll see about contacting Comp to see if there is any type of identifying number on the cam.
