Carbureted LSX Forum - ptv clearence




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1badeagle
02-12-2012, 01:26 PM
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.

http://i139.photobucket.com/albums/q315/1badeagle/2012-02-12_11-18-36_595.jpg

http://i139.photobucket.com/albums/q315/1badeagle/2012-02-12_11-49-20_220.jpg

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?


Doug G
02-12-2012, 01:47 PM
Been told .060 was max before alignment issues ???? But I would look into deeper :nod:

3pedals
02-12-2012, 01:57 PM
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.


Z284thgen
02-12-2012, 03:24 PM
whats it measure if you cut in center of the valve from top to bottom on each one


did the .250/.230 come from the center cut across the intake to exh valve like in pic 1

1badeagle
02-13-2012, 12:38 AM
I just measured with a caliber and i have .2665" intake and .221" on the exhaust side.

1badeagle
02-14-2012, 09:28 PM
I decided today im going to take the 3pedals route and mill my heads. 050". I want to run a .040" gasket over my. 051" gm gaskets. Who sells ls3 .040" gaskets the cheapest?

jtaylor16
02-14-2012, 11:20 PM
this akes me feel really confident going into my cam install 234/238 .650/.650 but with stock ls1 heads, gaskets, and pistons

1badeagle
02-15-2012, 02:53 AM
My friend runs a ms4 in a stock ls1.

bitterman
02-15-2012, 06:37 AM
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.

Subscribing :)

Regards,
Bruce

1badeagle
02-15-2012, 08:20 AM
Flat tops with 4cc reliefs for a 6.125" rod.

bitterman
02-16-2012, 06:30 AM
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

1badeagle
02-16-2012, 06:48 AM
I had beech performance build my short block. It was 1000$ to have everything balanced and assembled and set up for a 300hp shot of spray:D

1badeagle
02-20-2012, 08:11 PM
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.

jgillen91
02-20-2012, 08:24 PM
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

Prorac1
02-20-2012, 08:52 PM
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

twinturbo2
02-20-2012, 09:07 PM
what is acceptable ptv clearance i know .100 or is normal anybody run like .070 or is that a little close just wandering

1badeagle
02-20-2012, 09:21 PM
Damnit. I wanted to avoid doing the entire thing over again.

Prorac1
02-21-2012, 06:22 PM
For p to v clearance i have always heard that .060 on the intake and .080 on the exhaust. Eric L

1badeagle
02-22-2012, 09:26 PM
I tried to pull a lifter apart earlier. All i succeeded in doing was having the lifter pop apart and lost pieces. Youguysthink ill be fine with a .050" mill?

Prorac1
02-23-2012, 08:57 AM
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

1badeagle
02-23-2012, 05:57 PM
I went ahead and pulled 2 other lifters apart tonight. I pulled them apart, flipped the plunger put a small washer on top of the plunger. Then I put the little thin flat spacer thing back on and part that the pushrod rides on. I checked again with playdough and it looked exactly the same again. I will know the numbers for sure tonight after i get to work.

Gregory
02-23-2012, 08:27 PM
Sounds like you are doing everything correct to measure clearance.
I milled .072" from 243 series heads. There were some intake bolt alignment issues, but they were manageable. Keep in mind the thinner deck may warp when adding lots of nitrous.

1badeagle
02-23-2012, 11:11 PM
Ok guys, Just check the cleareances with my caliber. I have .2245" intake and .2005" exhaust. Can I run a .040" gasket and a .050" mill on the heads?

1badeagle
02-24-2012, 01:19 AM
With the mill work and thinner gasket I will have .1635" intake and .1395" exhaust. I think I will be fine with milling and a thinner gasket.

Prorac1
02-24-2012, 02:48 PM
That sounds like plenty of clearance. Eric L

1badeagle
02-24-2012, 07:47 PM
I sending my heads out tomorrow. This cars gonna be a monster.