Hi guys, so i have a ls1 and just installed the torquer v2 and have some lingenfelter cncd 243 heads and had .020 milled off yesterday to help my compression. Measured my ptv tonight with solid lifters and zero lash. My question for opinions and suggestionI came up with .110 on the exhaust valve - good since recommended is .100 but........ my intake is coming in at .065 and recommended is .080. I measured 2 cylinders And both were the same. Now when I measured i used the used graphite gasket that came off it which everyone says should be .041 thick compressed and i will be using the gm MLS gaskets which everyone says is .051 compressed. I measured the graphite and was coming in at .045ish but if the mls is indeed .051 compressed that would put my intake at .075 ptv clearance which is nothing to sweat. i really really do not want to flycut and i have a tune in 8 days but want this thing to be reliable and will do what i have to but really donot want to flycut.

So what do you all think? Even if im at .065 with the mls am i safe or do i need a flycut? Should technically be .075 with the mls... but just in case worst situation it was .065? The intake valve is chasing the piston At this point.

So???????????? Thanks everyone

 

is your car an auto or m6?

 

M6

It is a street car and will probably never see the track.

 

Ok, that's why I asked. being an M6 you have the risk of missing a shift and that's where the safety margin comes into play. If it was an auto I would think that .070 would be ok but since it's an M6 It's kind of a gamble. @ .075 you might be ok with an M6 but I would rather someone else chime in that has more experience to confirm that.

 

Most guys running big cams in cam only applications are much closer than that. While .080" is ideal, you can certainly run it. Just be aware that you may kiss or "eyelash" the pistons if you miss a shift.

 

Yeah thats what ive read too and i also read the exhaust is the one to be careful with since it sees more heat and the piston is chasing the valve instead of the valve chasing the piston down.

Anyone else have opinions on this?

 

On my auto, I've ran .058 average on my intake side for around 300 miles now. These miles have been pretty rough ones though. Car has seen rev limiter multiple times and no glitches yet.some people get lucky, some don't. In my opinion, I THINK you will be ok. There is only one way to know for sure though..

 

Not sure I would count on graphite gaskets having a thinner compressed thickness. There seems to be some debate on that issue. Looks like according to GM, both graphite and MSL gaskets are the same compressed thickness.

 

Im stuck at what I should do. I will flycut if i have to but then i won't make it to my tune and will be about a month out til the next available date.

 

It's your money, so no one can tell you one way or the other. With that said, I know I'm going to be closer than .050" intake and I'm not flycutting. I went as big as I could and milled as much as I could without flycutting. That means I also am going to be running it pretty damn tight. But it's my choice.

 

If you are 100% sure that you have .075 ptv clearance then I would run it. .005 is not that big of a difference, either way even at .080 you still have the same risk of missing a shift and reving it to the moon with ptv contact.

 

Change to a different cam?

 

If you have an adjustable timing set, you can retard the cam a degree or two and pick up some clearance.

 

Im not positive i have .075 clearance as im just assuming the mls is .010 bigger than the graphite gasket i used like most people have claimed. If it's not though then im at .065 at the minimum and just looking for some success stories with that clearance on the intake valve or if 8 times out of 10 im going to run into kissing that valve into the piston?

 

I didnt opt for the adjustable timing and i want to stick with my cam. Basically just trying to get feedback if im doomed and have to flycut or if i dont have anything to worry about and go ahead and bolt it together. Thanks for the feedback and youre running much closer than me jake...im going to have rev limiter set at 6700 and prob shift around 6300 if im ever really running it that hard which will be pretty rare. I have read about plenty of people who have run closer than me but who personally has a success story and put 20k+ on their setup without issues and close intake ptv?

 

LG used to run the G5X3 with AFR 205s milled to 59cc and a .040" Cometic. PtV is like .020" on that. T-Rex is good for about .020" clearance on stock heads. Just what you're comfortable with.

 

And LG never had any issues? Did LG ever pull the heads and see any contact between the valve and piston? Many people run trex cams at that clearance and no issues?

 

Your pistons will show eyelashes. That's a given. And I'm sure a few blew up. I just don't see it on the forums much.

 

65 is more than adequate on the intake, I would run it without question. My last motor was 35 on the intake and 40 or so exhaust and I spun it to 7000 almost daily, never had a problem. Exhaust is all you really need to be concerned with, with deflection and flex the intake chasing the piston will NEVER contact with that much room

 

Sorry if this is a dumb question but what does eyelashes mean?