ptv clearence
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ptv clearence
Just wanted to show all you guys my ptv clearances on my 6.1 lq4. The clearance was checked with stock gm .054 head gaskets, stock ls3 heads, 4.030 mahle l92 pistons. The cams specs 235/243 .621/.623 110+4.
As you can see, i have a easy. 250" on intake and .230" on the exhaust side. I can tell you that the valves would have hit the pistons if i had not had aftermarket pistons. I am planning on milling .045" of the heads and having them ported as well.
Does anyone know how far you can mill the stock heads before you have issues?
As you can see, i have a easy. 250" on intake and .230" on the exhaust side. I can tell you that the valves would have hit the pistons if i had not had aftermarket pistons. I am planning on milling .045" of the heads and having them ported as well.
Does anyone know how far you can mill the stock heads before you have issues?
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I know of a set that was cut .070". I am sure the intake bolt hole would need to be ovaled slightly at that point, and maybe small port match work done.
At .050" I had NO intake bolt or port alignment problems. I wont even flinch at cutting .070" if needed to get compression up.
At .050" I had NO intake bolt or port alignment problems. I wont even flinch at cutting .070" if needed to get compression up.
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#9
Very interesting.... Are those flat tops for the 3.662 stroke and 6.098 stock rods? Or do the pistons require 6.125" rods?
I might think about changing pistons on my ly6 at some point later on and shave the heads for compression too.
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Regards,
Bruce
I might think about changing pistons on my ly6 at some point later on and shave the heads for compression too.
Subscribing
Regards,
Bruce
#11
What did it cost to balance your rotating assembly for the new rods and pistons?
When I decide to take mine apart, I going to do pistons, rods and balance everything, then shave the heads... by then I might also up the cam depending on how thigns go with my current ly6 cam only build.
Bruce
When I decide to take mine apart, I going to do pistons, rods and balance everything, then shave the heads... by then I might also up the cam depending on how thigns go with my current ly6 cam only build.
Bruce
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I feel like such an idiot right now. I just realized that i didnt make my lifters solid when i checked my ptv clearances. How much ptv clearence do you lose when you make the lifters solid? Will i still be ok with a .050" mill? I was thinking about milling and running a bit thinner gasket as well like 3pedals is.
#14
I feel like such an idiot right now. I just realized that i didnt make my lifters solid when i checked my ptv clearances. How much ptv clearence do you lose when you make the lifters solid? Will i still be ok with a .050" mill? I was thinking about milling and running a bit thinner gasket as well like 3pedals is.
set you adjustable pushrod checker to the correct pushrod length. then turn engine over. mine needed a 7.325" pushrod that is with .080 lifter preload. i checked ptv clearance with my ls7 lifter preloaded. sounded like the right way to do it in my head but i am sure a solid lifter is desireale
it took 1 3/4 turns to get the torque wrench to click off at 22 ft lbs
1 turn + .047 preload do the math lol
Last edited by jgillen91; 02-20-2012 at 09:13 PM.
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I pulled the clip out of one of my factory lifters, pulled the internals apart, flipped the plunger around and assembled the lifter without the spring. Walla.......a solid lifter. Thats how I checked mine. Eric L
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I wouldnt do anything, no matter how much clearance I thought I had, until I checked. Use a pen magnet to pull the guts out of the lifter cause the little bit of oil in the lifter will try to suck the piston back down. Hope this helps, Eric L