ptv measurement opinions?
ptv measurement opinions? Hey guys, destroyed my 6.0 by dropping something into the cylinder and didn't even notice until it was too late, yep it sucks anyways..
Had the machine shop assemble pistons on a 5.7 I had laying around and polished the 6.0 crank and balanced everything, so I am assembling this right now, with 243 heads with just a slight mill to clean the surface not sure how much PRC cut them down.
Cam is a 231/234 .617/.612 on a 112 lsa, and I saw that it's pretty similar to an ms4 cam so I decided to check my ptv just incase.
Im trying not to fly cut the pistons so any reccommendations are welcome. I know it can be done and done without removing the pistons but I would just like to find an alternative solution whether it be a thicker head gasket or smaller cam, or retarding/advancing the cam
So here are my measurements, I followed one of the threads around here where Tony Mamo told someone how to do it: install checker springs with the hyd lifters, pushrod checker torque the rocker down and set the pushrod to 0 lash and check 20 degrees before and after tdc.
I took a lot of time to take these measurements, however I used the timing dots to set my tdc with the degree wheel, I figured because I was going 20 before and after it shouldn't be that important as long as I have this many measurements to go off of
The + is after tdc and the - before
+20 0.093
+18 0.079
+16 0.067
+14 0.059
+12 0.054
+10 0.052
+8 0.050
+6 0.051
+4 0.057
+2 0.065
0 0.077
-2 0.087
-4 0.100
-6 0.116
-8 0.132
-10 0.153
-12 0.174
-14 0.202
-16 0.233
-18 0.256
-20 0.295
Had the machine shop assemble pistons on a 5.7 I had laying around and polished the 6.0 crank and balanced everything, so I am assembling this right now, with 243 heads with just a slight mill to clean the surface not sure how much PRC cut them down.
Cam is a 231/234 .617/.612 on a 112 lsa, and I saw that it's pretty similar to an ms4 cam so I decided to check my ptv just incase.
Im trying not to fly cut the pistons so any reccommendations are welcome. I know it can be done and done without removing the pistons but I would just like to find an alternative solution whether it be a thicker head gasket or smaller cam, or retarding/advancing the cam
So here are my measurements, I followed one of the threads around here where Tony Mamo told someone how to do it: install checker springs with the hyd lifters, pushrod checker torque the rocker down and set the pushrod to 0 lash and check 20 degrees before and after tdc.
I took a lot of time to take these measurements, however I used the timing dots to set my tdc with the degree wheel, I figured because I was going 20 before and after it shouldn't be that important as long as I have this many measurements to go off of
The + is after tdc and the - before
+20 0.093
+18 0.079
+16 0.067
+14 0.059
+12 0.054
+10 0.052
+8 0.050
+6 0.051
+4 0.057
+2 0.065
0 0.077
-2 0.087
-4 0.100
-6 0.116
-8 0.132
-10 0.153
-12 0.174
-14 0.202
-16 0.233
-18 0.256
-20 0.295
Joined: Aug 2007
Posts: 24,241
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From: Turnin' Wrenches Infractions: 005
The 50 is a smidge on the close side. I had 120 and 100 and cut my heads 30 to get me down to 90 and 70, obviously. I've had no issues, I've been on the limiter a few times but obviously I try like hell to stay off. I started with around a 6600 limiter but think I'm up to 6800ish now. I also shimmed my springs up 30 iirc to get them at 60 before coilbind at max cam lift. Cam is cam motion 228/232 613/613 113+4.
I started to check them again and was getting a difference of an additional .007 on each measurement every 2 degrees. So maybe I will take the tool back off and reset the dial indicator and take a couple more rounds of measurements
Checked them again and they are still way too close for me to not lose sleep over. I guess I can either get a smaller cam, flycut, or find another lq4 shortblock. This blows
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
What are you deeming as too close? Obviously there are varying opinions on what's too close. I believe Cometic makes a thicker gasket though it is a little pricey.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Also, remember this, the intake chases the piston, the exhaust gets chased. Generally its acceptable to run tighter clearance on the intake valve because of this. Did you check both?
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Well the 0.050 is close however you need to add 0.015 as has been seen in here to account for deflection in the push rod and springs. I have prc duals so I'm hoping there shouldn't be issues on top.
I reached out to a member on here here may have the fly cutting tools and is in my town but if that doesn't happen I think I may run it
I haven't checked exhaust yet but I will beforeIo make a decision
I reached out to a member on here here may have the fly cutting tools and is in my town but if that doesn't happen I think I may run it
I haven't checked exhaust yet but I will beforeIo make a decision
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Just to double check, where are the dots? I found mine was tighter than Tony thought it should be and when I double checked the cam degree found it was off slightly. I had to re-degree the cam and re-check. In the end I had 0.069" of clearance. Also, make sure when you measure your gasket is correctly mocked up for thickness.
Since the + is after the piston has gone by, the valve is chasing the piston and will never catch it. I think if you do some searching you will find that some run down to 0.040".
Since the + is after the piston has gone by, the valve is chasing the piston and will never catch it. I think if you do some searching you will find that some run down to 0.040".
The numbers I've generally seen to be really safe are .080 intake and .100 exhaust although I ran .060 on the intake without issue. The exhaust I would not want to fudge on.
The cam is just installed dot to dot as I tried degreeing the cam in the 6.0 it ended up being right on. I suppose I should double check of course.
I was going to go over there last night and check it out again and try doing another clay test but ran out of motivation on the way home.
Now is everyone's measurements using a dial indicator, and without adding in anything extra?
Also I've read on here to check with the clay method to use the checker springs and an adjustable pushrod set to 0 lash? Or should I assemble everything with two solid lifters and try that way?
I was going to go over there last night and check it out again and try doing another clay test but ran out of motivation on the way home.
Now is everyone's measurements using a dial indicator, and without adding in anything extra?
Also I've read on here to check with the clay method to use the checker springs and an adjustable pushrod set to 0 lash? Or should I assemble everything with two solid lifters and try that way?
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Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
I have been running with .045 intake PVC for over a year with 3000+ street miles and 100+ street and track runs to 7000 rpm. No problems so far.
It is a COMP 54-459-11 cam (231/239 with 113 LSA, .624 lift).
I do have Patriot Extreme dual valve springs, Ti retainers, LS7 lifters,COMP pushrods.
I was also alarmed by the tight clearance, but willing to take a chance. No problems so far.
It is a COMP 54-459-11 cam (231/239 with 113 LSA, .624 lift).
I do have Patriot Extreme dual valve springs, Ti retainers, LS7 lifters,COMP pushrods.
I was also alarmed by the tight clearance, but willing to take a chance. No problems so far.