Too close to run??
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: Aug 2008
Posts: 617
Likes: 0
From: Alberta, Canada
Too close to run?? Guys, I was just doing some ptv checking and I got about .080-.085 on both intake and exhaust on LS3 heads going on a LQ4. Is this too tight to run?? The intake seems 'ok'ish from what Ive read, but the exhaust might be a bit tight.
I might have to do that cheap-o fly cutting trick and sacrifice a couple couple valves.
I might have to do that cheap-o fly cutting trick and sacrifice a couple couple valves.
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: Aug 2008
Posts: 617
Likes: 0
From: Alberta, Canada
So I just went and did the playdoh method. Check out the pics, I got. The tightest I measured was about .125, which is pretty good actually. Please look at my pics and see whats going on here. Its weird cuz I got such different values by mocking up and measuring with a dial indicator on the valve retainer and pushing on the rocker. I have checking springs installed.
What do you guys think of the way this looks??
What do you guys think of the way this looks??
well we were told by Advanced Induction on a friend of mines LT1 build that they go as tight as .050 on intake and exhaust... I thought that sounded tight but they know their stuff...
I think you would be ok with those clearances... However if you do Flycut..you would only need to on the exhaust side...
I think you would be ok with those clearances... However if you do Flycut..you would only need to on the exhaust side...
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: Aug 2008
Posts: 617
Likes: 0
From: Alberta, Canada
Matt, its an out of the box comp cams part number 54-470-11.
Intake Duration at 050 inch Lift 235
Exhaust Duration at 050 inch Lift 251
Duration at 050 inch Lift 235 int./251 exh.
0.621 int./0.624 exh.
LSA 113
I dont know what to think about this ptv clearance I got. One way I do it, I get really tight, another way I get lots of clearance. Just weird.
Intake Duration at 050 inch Lift 235
Exhaust Duration at 050 inch Lift 251
Duration at 050 inch Lift 235 int./251 exh.
0.621 int./0.624 exh.
LSA 113
I dont know what to think about this ptv clearance I got. One way I do it, I get really tight, another way I get lots of clearance. Just weird.
TECH Enthusiast
Joined: Apr 2007
Posts: 709
Likes: 2
From: 336 NC
With a dial indicator you got .080"-.085" at TDC pushing the valves down by hand? With playdoh you got .125"... was that pushing the valves by hand or turning the motor letting the cam move the rockers and valves?
Trending Topics
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: Aug 2008
Posts: 617
Likes: 0
From: Alberta, Canada
I might actually go and do this again and put the playdoh down and put the dial indicator on the spring retainer to make sure its going down the entire amount and not squishing the lifter. Im sure it didnt, but measuring is the only way to find out for sure.
EDIT: Also, that .080-.085 was actually not at TDC, it was a few degrees before I believe. I didnt have degree wheel on when I did that. But it wasnt at max lift Im pretty sure.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: Aug 2008
Posts: 617
Likes: 0
From: Alberta, Canada
Yes, a head gasket was in there too.
I did some more playing, found out my lifters (especially the intake one) were squishing about .100 or so and therefore throwing off my readings.
So I converted an old lifter to be solid and re-did the playdoh method with a dial indicator on to make sure all the lift was coming in. It was. The playdoh still looked good actually, the smallest I got was on the exhaust around .120, which is good, I think.
So with "solid" lifters, a head gasket totally torqued down the thinnest playdoh I got was around .120. The thinnest is where the top of the piston dips down into the dish of the piston, along that edge there.
I did some more playing, found out my lifters (especially the intake one) were squishing about .100 or so and therefore throwing off my readings.
So I converted an old lifter to be solid and re-did the playdoh method with a dial indicator on to make sure all the lift was coming in. It was. The playdoh still looked good actually, the smallest I got was on the exhaust around .120, which is good, I think.
So with "solid" lifters, a head gasket totally torqued down the thinnest playdoh I got was around .120. The thinnest is where the top of the piston dips down into the dish of the piston, along that edge there.
TECH Regular
iTrader: (5)
Joined: Jan 2008
Posts: 452
Likes: 2
From: Sparta, Mo. in southwest Missouri
Yes, a head gasket was in there too.
I did some more playing, found out my lifters (especially the intake one) were squishing about .100 or so and therefore throwing off my readings.
So I converted an old lifter to be solid and re-did the playdoh method with a dial indicator on to make sure all the lift was coming in. It was. The playdoh still looked good actually, the smallest I got was on the exhaust around .120, which is good, I think.
So with "solid" lifters, a head gasket totally torqued down the thinnest playdoh I got was around .120. The thinnest is where the top of the piston dips down into the dish of the piston, along that edge there.
I did some more playing, found out my lifters (especially the intake one) were squishing about .100 or so and therefore throwing off my readings.
So I converted an old lifter to be solid and re-did the playdoh method with a dial indicator on to make sure all the lift was coming in. It was. The playdoh still looked good actually, the smallest I got was on the exhaust around .120, which is good, I think.
So with "solid" lifters, a head gasket totally torqued down the thinnest playdoh I got was around .120. The thinnest is where the top of the piston dips down into the dish of the piston, along that edge there.
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: Aug 2008
Posts: 617
Likes: 0
From: Alberta, Canada
Thanks Ron, I appreciate the help. I did the check it every few degrees thing too. With the pics of the playdoh, you can see there is lots of clearance there. I think the playdoh doesnt lie, it will show the minimum clearance no matter where in the rotation it happens.
I actually sent you a PM back before I seen you came back in here, I appreciate the help.
I actually sent you a PM back before I seen you came back in here, I appreciate the help.
Launching!
Joined: Nov 2010
Posts: 251
Likes: 0
The cam I WANT is a custom spec 231@.050" w/ .617" lift and 243@.050" w/ .624" lift 113+4 on LSL lobes
I know my heads cut .030" make it closer to the piston, but your increase in duration also puts you closer to the piston. I just wonder by how much though...
My pushrods are 7.425", that was given to me from the guy who sold me the cam. When I swap cams I want to measure it to verify.
What lifters are you running?
Also, your head gaskets crush to .051", correct? Would you be able to do a quick mock up with a .020" shims and the playdoh? If you cant its cool just wondering while your engine is on a stand.
Sounds like you are good to go...cam should sound nasty too...
I am running a EPS 230/242 with all stock LQ9 block and LS3 heads....
Came up with .096 intake and .109 exhaust... Using a solid lifter...
I am running a EPS 230/242 with all stock LQ9 block and LS3 heads....
Came up with .096 intake and .109 exhaust... Using a solid lifter...
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: Aug 2008
Posts: 617
Likes: 0
From: Alberta, Canada
I am running Comp 850 lifters. Im not sure, they could be the same as something else, like an LS7 lifter....I dont know. Those gaskets supposedly crush to .051". I took a previously crushed one and mic'd it while pressing it together, and the smallest number I could get was .051".
Ya, Im going to put the heads on today and close this chapter of the engine assembly I hope.
Thanks for the help guys.
Ya, Im going to put the heads on today and close this chapter of the engine assembly I hope.
Thanks for the help guys.
Thread Starter
TECH Enthusiast
iTrader: (2)
Joined: Aug 2008
Posts: 617
Likes: 0
From: Alberta, Canada
Im going to obsolutely lose my mind.
Today I decided to check ptv with the dial indicator and solid lifters in and torque the head down with a gasket and checking springs in. Intake I got like .035 intake, .070 exhaust before the valve stopped going down. Im going to stab myself in the eye with my dial indicator soon. I even pushed on the valve and rotated the engine a bit to make sure it was hitting the piston and it was the piston.
How is this possible?? Im so pissed right now, I dont know what to do anymore.
Today I decided to check ptv with the dial indicator and solid lifters in and torque the head down with a gasket and checking springs in. Intake I got like .035 intake, .070 exhaust before the valve stopped going down. Im going to stab myself in the eye with my dial indicator soon. I even pushed on the valve and rotated the engine a bit to make sure it was hitting the piston and it was the piston.
How is this possible?? Im so pissed right now, I dont know what to do anymore.