Checking PtoV without pulling head?
Thread Starter
Joined: Nov 2001
Posts: 7,303
Likes: 4
From: Delray Beach, Fl.
Checking PtoV without pulling head? I have milled LS6 heads .030 and 2.02/1.57 valves.My current cam is 224-580 113LSA but I hate the idle,it almost sounds stock.I want to go with a X1 or R1 or maybe even a GX3 but I dont wanna pull the heads.Can Icheck p/v w/o pulling the heads.
Also doesnt it seems strange that Cartek nothched my pistons for a 224-580 cam?I had the cam dr'ed so I know this is the size but GOD I would think it wouldve never needed to be notched?I saw the notches on the bore scope so I know there done.
What cam do u think I could go w/now w/o checking p/v?
I run 7.35 PR's if thats a help?
Also doesnt it seems strange that Cartek nothched my pistons for a 224-580 cam?I had the cam dr'ed so I know this is the size but GOD I would think it wouldve never needed to be notched?I saw the notches on the bore scope so I know there done.
What cam do u think I could go w/now w/o checking p/v?
I run 7.35 PR's if thats a help?
i'm just curious how, exactly, it is that you check PtV. i've come to understand you pull the heads, and place clay between the piston and the valve, replace the head, and rotate the cam to check valve events. slap me over the head and correct me if i'm way off target. is there how-to that is more detailed that you guys could link me to? ie thickness of clay, whether you start the process with the motor at TDC, BTDC, ATDC, whatever. i'd really appreciate it.
Originally Posted by 2001CamaroGuy
only way is to clay.......... 
Call Trevor at TSP he will tell you how to do it with the Dial Indicator.
Depending on whom did your LS6 heads, you may be as big as you can get for cams.
I have on order a set of LS6 Heads from Absolute Speed. According to Jay, with his LS6-Head setup, 2.02/1.57 valves, milled .030", the biggest cam that can be installed with this head is a 224/224 112 + 4 LSA. That nets a TIGHT P-t-V clearance of like .060" or so.
So, for me, I am only getting my LS6 heads milled .020", and am going with a 224/224 114 LSA (0 advance). I'd rather be a bit safer than try to eek out another 3-5 HP.
I have on order a set of LS6 Heads from Absolute Speed. According to Jay, with his LS6-Head setup, 2.02/1.57 valves, milled .030", the biggest cam that can be installed with this head is a 224/224 112 + 4 LSA. That nets a TIGHT P-t-V clearance of like .060" or so.
So, for me, I am only getting my LS6 heads milled .020", and am going with a 224/224 114 LSA (0 advance). I'd rather be a bit safer than try to eek out another 3-5 HP.
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Lift, duration, and advance all play parts in the clearence. It's all about the valve timing. If the heads you have were milled .030", and the cam was a 224/581"+4, then I could see needing the pistons cut. You can measure by the valve drop method, but you will have to know how much clearence is need for a particular cam. I believe this is were the ol' dial indicator comes in handy. You might want to check with Trevor for that.
Thread Starter
Joined: Nov 2001
Posts: 7,303
Likes: 4
From: Delray Beach, Fl.
I knew u cold do it,My buddy told me u can use a dial indicator on the valve and use a wheel.Then spin the motor around when the piston is at its highest spot.I dont know the theory but I'm gonna cal Trevor.
If he helps me I'l run one of his cam
Thanks guys,If not I guess I'm gonna just leave it alone.
The cam is a 224-224 580-580 113LSA+2 but I might put it back where I was told to put in which was straight up on a 113ICL.I still hate the stock like lope,I wish I had a T-rex or something badass in my car
If he helps me I'l run one of his cam
Thanks guys,If not I guess I'm gonna just leave it alone.
The cam is a 224-224 580-580 113LSA+2 but I might put it back where I was told to put in which was straight up on a 113ICL.I still hate the stock like lope,I wish I had a T-rex or something badass in my car
Launching!
Joined: Nov 2001
Posts: 271
Likes: 0
From: Wilmington DE
You don't have to pull the head. What you do is set up a dial indicator so it can measure the valve movement from the tip of the valve. You need to install a soft spring on the valve you are checking. Once you have that set up, you rotate the engine around so that the cam/piston is at specific points (there are a few different spots you need to check it at). When you are at the point you want to measure, you push the valve down until it touches the piston, and you have your measurement. This is a basic description of the process. Don't know if it helps you much or not... Good luck.
Launching!
Joined: Nov 2001
Posts: 271
Likes: 0
From: Wilmington DE
The lifter doesn't really matter. You need to remove the pushrod on the valve you are checking. I guess you could leave it in so you know where that particular cam lobe is at. The key is once you have the cam lobe and piston in the right position, you push the valve in with your finger (hence the need for the soft spring) until it hits the piston. That is the measurement you need to check. You also need to verify the exact lift on your cam before hand so you can subtract that from the measurement you get from depressing the valve. Hopefully after you subract your valve lift amount, you will have enough clearance left over.
You absolutely do not have to clay the motor.It is actually pretty easy to do.Get an adjustable pushrod and a tester spring.(light but enough to hold valve closed).
Put tester spring on valve.Adjust pushrod for 0 lash with rocker bolted in place.Put dial indicator on retainer.Spin the motor while pushing valve down to measure P/V clearance.On tight spot's check it throughout the rotation.
Doesn't take long to do.
Put tester spring on valve.Adjust pushrod for 0 lash with rocker bolted in place.Put dial indicator on retainer.Spin the motor while pushing valve down to measure P/V clearance.On tight spot's check it throughout the rotation.
Doesn't take long to do.
Launching!
Joined: Nov 2001
Posts: 271
Likes: 0
From: Wilmington DE
If you look at the cam manufacturer's recommended PtoV clearance, it should be plenty to accomodate for the lifters pump up. For some reason I remember it being like .030 or something. Its best to verify the number though (it is probably different for intake and exhaust too). But this is also why you want to get an ACCURATE measure of the exact lift of your cam. If you had a solid lifter to put in there it would help, but with an LS1 that would be a huge PITA.
Thread Starter
Joined: Nov 2001
Posts: 7,303
Likes: 4
From: Delray Beach, Fl.
I understand how to do it now..
Slowhawk thats how my buddy Pete said to do it.
But he said that only gonna give u lift,To do duration too u would use a degree wheel in conjunction w/the lw springs/dial indicator/pr checker.
Slowhawk thats how my buddy Pete said to do it.
But he said that only gonna give u lift,To do duration too u would use a degree wheel in conjunction w/the lw springs/dial indicator/pr checker.
I did mine the way Slowhawk described (btw, Comp and Crane have more detailed instructions on their web sites). I put my degree wheel on the crank, set it to TDC on the cylinder I was checking, then checked the P-V clearance on the intake and exhaust for each degree of rotation from 10* BTDC to 10* ATDC. The intake will be closest AFTER TDC and the exhaust will be closest BEFORE TDC.
As long as you use a light check spring on the valves and set the lash to 0 with an adjustable pushrod, the lifter pump up shouldn't come into play.
This will give you absolute clearance based on the cams lift AND duration.
Of course by the time you're doing this your new cam is already in the motor and if it's too big you're screwed. Don't ask me how I know.
You can do a "valve drop" check first before you buy the new cam or pull anything apart and compare that to the recommended amount for the cam you are considering. That will at least get you in the ball park. The G5X3 for example requires .200"-.210" of valve drop with the piston at TDC for it to clear. Regardless, you still need to check it once it's in the motor though.
As long as you use a light check spring on the valves and set the lash to 0 with an adjustable pushrod, the lifter pump up shouldn't come into play.
This will give you absolute clearance based on the cams lift AND duration.
Of course by the time you're doing this your new cam is already in the motor and if it's too big you're screwed. Don't ask me how I know.
You can do a "valve drop" check first before you buy the new cam or pull anything apart and compare that to the recommended amount for the cam you are considering. That will at least get you in the ball park. The G5X3 for example requires .200"-.210" of valve drop with the piston at TDC for it to clear. Regardless, you still need to check it once it's in the motor though. Thread Starter
Joined: Nov 2001
Posts: 7,303
Likes: 4
From: Delray Beach, Fl.
Here's my dilema,I am afraid to pull the cam and lose power.I've seen some threads where guys pulled a cam like mine (224-224 580-580 113) for something bigger only to gain 5RW or even lose power.Slowhawk sez leave it alone and add the 90MM/LSX and that should get me about 10 to 15RW so I'm confused as to where to spend $$$.
Cam and retune
LSX/90MM and retune.
The car is making 410RW at a nice 6000 rpm peak carrying to 6500
It makes broad tq 399RW from 4400 to 4800 peak carring to 4800
So I dont know if I should go more cam or just say 410RW threw fairly mild S2 H/C AUTO is pretty good and just add the intake and TB for another 10 to 15RW.That would put me around 420 to 425 threw the A4 which for this cam is pretty good.
The only thing is the cam sounds mild w/a 113LSA.
It doesnt lope at all,more of a steady bla bla bla bla bla...
Cam and retune
LSX/90MM and retune.
The car is making 410RW at a nice 6000 rpm peak carrying to 6500
It makes broad tq 399RW from 4400 to 4800 peak carring to 4800
So I dont know if I should go more cam or just say 410RW threw fairly mild S2 H/C AUTO is pretty good and just add the intake and TB for another 10 to 15RW.That would put me around 420 to 425 threw the A4 which for this cam is pretty good.
The only thing is the cam sounds mild w/a 113LSA.
It doesnt lope at all,more of a steady bla bla bla bla bla...