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Is .060 intake .080 exhaust safe piston to valve clearance?
Im about to officially pull the trigger on purchasing my cam. As a rule of thumb I've always been told .080 intake .100 exhaust is safe. I was told by the vendor that manufacturers this cam will have around .060 intake and .080 of clearance in a stock LS3 with stock heads. Are these good safe #'s to be comfortable enough without any concerns?
If Cam Motion stated 0.060" and 0.080" will work, I would run it. Since the clearances will be closer than normal, it would be best to check after cam is installed.
If Cam Motion stated 0.060" and 0.080" will work, I would run it. Since the clearances will be closer than normal, it would be best to check after cam is installed.
Lets see what others say when they chime in.
Car is an 01 Z28 with brand new LS3 crate motor. Auto with a yank 3600ss converter. Plan on having max rpms around 6500-6700
Seems a little tight what happens if your heads have been or will be shaved in the future? Or you have an outlier pushrod valve that is like .010 off or so from the others. Since you have no margin for error you will need to keep an eye on the valve springs.
Andy , I just had a cam speced by PAt G and the intake was at 47 . Pat said was a little tight but doable . Mine has already had all the mods its going to have unless I fly cut which I am not doing at this time . This is on stock ls2 alum block . Tell me if I am wrong . The alum block will grow with heat so the the piston to valve should gain a little more clearance. I would like to know if this is correct .
I have already ordered my cam but not put in yet . As long as the valve train is stable I would say I will be ok based off of what Pat G has said . I do plan to turn mine to 6800
Andy , I just had a cam speced by PAt G and the intake was at 47 . Pat said was a little tight but doable . Mine has already had all the mods its going to have unless I fly cut which I am not doing at this time . This is on stock ls2 alum block . Tell me if I am wrong . The alum block will grow with heat so the the piston to valve should gain a little more clearance. I would like to know if this is correct .
I have already ordered my cam but not put in yet . As long as the valve train is stable I would say I will be ok based off of what Pat G has said . I do plan to turn mine to 6800
i haven't ordered mine yet still looking at all the options. I'm also considering the Brian Tooley stage 3 which is a 229/244 113+4. I talked to someone from BTR not Brian himself and they said that one had an estimated clearance of .055 intake and .090 exhaust. I'm assuming going by this all the LS3 cams are going to be a little tight on the intake side. Just something I'm not used to I guess. This is my first rectangular port headed motor so it's new to me
Not a Ls3 but on my Ls1 I had .040" intake .065" exhaust and decided to cut valve reliefs. If you are going to have the heads off it is pretty straight forward. I cut .030" reliefs with a 239/244
Not a Ls3 but on my Ls1 I had .040" intake .065" exhaust and decided to cut valve reliefs. If you are going to have the heads off it is pretty straight forward. I cut .030" reliefs with a 239/244
Nice job on flycutting. Did you use a Lindy Tool? That is what I used on mine. Very easy to do. My LS3 heads were milled .030" and used .040" head gaskets with a Cam Motion cam 230/238 .626 113+3 spec'd by Pat G. He suggested flycutting .050". Came up with 11.27 compression and pulled 480/434 on the dyno. SAE corrected.
Nice job on flycutting. Did you use a Lindy Tool? That is what I used on mine. Very easy to do. My LS3 heads were milled .030" and used .040" head gaskets with a Cam Motion cam 230/238 .626 113+3 spec'd by Pat G. He suggested flycutting .050". Came up with 11.27 compression and pulled 480/434 on the dyno. SAE corrected.
Yes it was the Lindy tool. Definitely not a bad job at all.
PRC 243's milled .030" and a .040" gasket here also.
I had my doubts as I cut into the first piston top but after pulling the head off and seeing the results, It was smooth sailing
I would do that fly cut the piston with that tool. The extra .030 is a nice extra cushion to have and really does nothing much to affect the compression.
The cathedrals are a little more forgiving on the clearance though than the rectangular port heads. I don't plan on having mine milled. There's plenty of guys that run the BTR stage 4 on the LS3 so I would think I would be ok
This is again in a Ls1 but my buddy just installed a tick sns stg 3 235/243 .630"/.610"
Ported 243's milled but I don't remember how much. Valves sunk about .015"
If I remember correct intake .070" exhaust .090"
If that's of any help I can find out exactly
Im trying to decide between the Cam Motion cam mentioned earlier or the Tick stage 2 just seeing if anyone has any real world experience #s with either before I pull the trigger and order either one
I used the SS4 (236/254 .646/.637 111+4) fly cut version from gpi. Cut .120 valve reliefs and spin it to 7650. They have a no fly cut version (235/250 .646/.637 112+3) and have had great success with it.
05-27-2017, 04:45 PM
Is .060 intake .080 exhaust safe piston to valve clearance? 
