LS1GTO Forums banner
1 - 20 of 26 Posts

·
Registered
2004 GTO H/C/I. 430whp (hub dyno)
Joined
·
240 Posts
Discussion Starter · #1 ·
So little back story before i ask my question.
I bought this 2004 gto with a rebuilt motor (ls1) and stage 2 ( t56)The motor/trans has about 15,000 miles on it. Along with that rebuild the previous owner put ls6 Prc stage 2.5 heads on it, ms4 cam, along with full bolt ons. Well I bought the car knowing it was gonna need a top end rebuild due to the ticking noises. While I was tearing down the top end I believe I found the source of my "ticking noise" 1) found a snap ring on one of my rockers was bend out of shape. 2) one of the valve stems seals was just bouncing around in the spring wasnt even seated on the guide. Along with the valve stem seals. Half of them were obliterated as in non existent ( was burning oil before rebuild) Again i somewhat knew what i was getting into before i bought this gto. So here I am about "done" with the rebuild. I'm now measuring for pushrod length since I put in ls7 lifters ( morels 7177). Well I measured off of cylinder 2 so far. The exhaust valve measured out at 7.575 with .060 preload. So I go to double check my work and measure the intake with the same length. Well let's just say I only got to about .030 preload before my torque wrench clicked ( using a brand new craftsman 3/8 click type wrench. I bought it specifically for this rebuild) . So I instantly redid the whole process on the intake valve.... same thing. So I went back and quadruple checked the exhaust valve. It was still getting .060 preload.
Is the ms4 cam known to have different length pushrods? Or is it because of the aftermarket ls6 Prc heads? The original pushrods were (TSP 7.450 .080) so I'm guessing the preload was way off to begin with if I'm running into this issue.
I'm gonna continue and measure every valve now because of this. I'll update as I go. Go ahead and give me some feed back if you guys have ran into this problem with this cam and heads combo.
Had a catch can installed since rebuild so the motor wasnt to gunked up at all.
(Rebuild parts I've used.)
1) new MLS. 051 gasket. Same thickness as the old one.
2) Btr valve stem seals( yes I used the valve stem tool sold by Btr. Coated them in assembly lube so I didn't damage any of them upon installation)
3) I reused the valves and springs. All of them seemed to be in good condition.
4) I reused the arp bolts along with arp ultra torque lube. Followed arps torque specs and torque sequence to a T.
5) new ls7 morel 7177 lifters. ( no I didn't soak them. Read that it could mess with preload.)
6) I coated everything in Lucas assembly lube before putting back together. Coated everything not soaked.
7) I inspected the camshaft through the lifter slots with a flashlight while rotating the motor. No scoring of any kind on the cam.
8) yes I cleaned the heads and block surface for hours before putting it all back together.
 

·
Registered
2004 GTO H/C/I. 430whp (hub dyno)
Joined
·
240 Posts
Discussion Starter · #2 ·
Update
Measured cylinders 2,4,6,8 (exhaust valve)
All were consistent with preload (.060) with 7.555 inch pushrod. Give or take +.005
Unfortunately my comp cams adjustable is 7.4-7.8( well I tried lengthing it past 7.7 and it kinda gets all wobbly due to it running outta threads) at 7.7 I was getting about .075 preload.
So I was un able to test the intake valve.
But at least I have consistency throughout the exhaust valves on 2,4,6,8. I'll check 1,3,5,7 tommorow.
 

·
Registered
Joined
·
213 Posts
Yea, measure the exact clearance between lifter cup and rocker arm. Then order sticks that are .60 over. Personally, I would set them at .80 with a .120 lifter. It makes the lifter act more like a solid. Call Morel and find out the lifter travel.

Second, I know you have after market heads. But, are you sure of 7.5 length. The pedestal height must be high with those heads. For, instance I am 7.3 with .20 milled OE 243s. Incorrect pushrod length maybe the cause of some of your problems. Let us know what you find.
 

·
Registered
2004 GTO H/C/I. 430whp (hub dyno)
Joined
·
240 Posts
Discussion Starter · #6 ·
Yea, measure the exact clearance between lifter cup and rocker arm. Then order sticks that are .60 over. Personally, I would set them at .80 with a .120 lifter. It makes the lifter act more like a solid. Call Morel and find out the lifter travel.

Second, I know you have after market heads. But, are you sure of 7.5 length. The pedestal height must be high with those heads. For, instance I am 7.3 with .20 milled OE 243s. Incorrect pushrod length maybe the cause of some of your problems. Let us know what you find.
I was measuring wrong apparently. I put check springs in cyl #2 and instead of finding zero lash I was finding preload with my adjustable. Simple mis understanding glad I reached out to the forums for help or I would have goofed up real bad.
 

·
Registered
2004 GTO H/C/I. 430whp (hub dyno)
Joined
·
240 Posts
Discussion Starter · #7 ·
Update
After work today I simply just measured the exhaust valve on cylinder #2 to double check my "preload " numbers.
Yes I researched how to properly find zero lash and once torqued down you simply add you desired preload and that your pushrod length. Still getting 7.555.
 

·
Worthless reject member
Joined
·
55,257 Posts
i would also just double check to make sure you're not compressing the internal lifter spring or opening the valve spring when you torque the rocker arm bolt down.

if you're having to crank down on the the rocker arm bolt the last few turns before you hit 22 ft lbs, something is compressing.
 

·
Registered
2004 GTO H/C/I. 430whp (hub dyno)
Joined
·
240 Posts
Discussion Starter · #11 ·
i would also just double check to make sure you're not compressing the internal lifter spring or opening the valve spring when you torque the rocker arm bolt down.

if you're having to crank down on the the rocker arm bolt the last few turns before you hit 22 ft lbs, something is compressing.
Ahhh you mean when you put the pushrod in and make sure it's in the lifter cup. But don't press down on the lifter and compress it. You'll feel the pushrod drop another inch or so when compressed. Yeah ill double check to make sure none of that is happening today.
 

·
Worthless reject member
Joined
·
55,257 Posts
Ahhh you mean when you put the pushrod in and make sure it's in the lifter cup. But don't press down on the lifter and compress it. You'll feel the pushrod drop another inch or so when compressed. Yeah ill double check to make sure none of that is happening today.
ideally, you should have the tiniest bit of play in between the lifter cup and rocker cup with the pushrod.
 

·
Registered
2004 GTO H/C/I. 430whp (hub dyno)
Joined
·
240 Posts
Discussion Starter · #14 ·
Y
ideally, you should have the tiniest bit of play in between the lifter cup and rocker cup with the pushrod.
Yeah I saw that once you find the zero lash length the rocker should be able to move side to side the tiniest bit. Then you add your desired preload to your pushrod length. Thanks for the help I'll update later.
 

·
Worthless reject member
Joined
·
55,257 Posts
Yeah I saw that once you find the zero lash length the rocker should be able to move side to side the tiniest bit. Then you add your desired preload to your pushrod length. Thanks for the help I'll update later.
that is NOT a good way to check. if you preload the lifter, once the lifter bleeds down, you'll be able to move the rocker back and forth slightly.

the play needs to be with the pushrod checker tool still being able move slightly. you should still be able to turn the checker slightly because there is minimal pressure on it, not move it up and down.
 

·
Registered
2004 GTO H/C/I. 430whp (hub dyno)
Joined
·
240 Posts
Discussion Starter · #16 ·
that is NOT a good way to check. if you preload the lifter, once the lifter bleeds down, you'll be able to move the rocker back and forth slightly.

the play needs to be with the pushrod checker tool still being able move slightly. you should still be able to turn the checker slightly because there is minimal pressure on it, not move it up and down.
Yes that's what meant. I just suck at grammar
 

·
Registered
Joined
·
213 Posts
What type of rockers are you using ?? That could be the reason for 7.55 sticks. Also, check if the rocker stands are OE or aftermarket. And also, what are the valve stem lengths??

First, put a straight edge accross the valve stem ends to see if they are even. Second, measure valve spring height. I don't understand this. SBC (gen I) sticks are 7.8-7.9. Somethin' wrong.
 

·
Registered
2004 GTO H/C/I. 430whp (hub dyno)
Joined
·
240 Posts
Discussion Starter · #18 ·
Oem rockers with the trunion upgrade. The rocker stands are new oem gm. Read through the engine build notes it says " cylinder head decks checked and skimmed"
 

·
Registered
2004 GTO H/C/I. 430whp (hub dyno)
Joined
·
240 Posts
Discussion Starter · #19 ·
What type of rockers are you using ?? That could be the reason for 7.55 sticks. Also, check if the rocker stands are OE or aftermarket. And also, what are the valve stem lengths??

First, put a straight edge accross the valve stem ends to see if they are even. Second, measure valve spring height. I don't understand this. SBC (gen I) sticks are 7.8-7.9. Somethin' wrong.
Ran the straight edge across all of them. It touches all of them
Maybe perhaps I was just measuring wrong. I'm gonna pay extra attention to make sure I'm not compressing the lifter at all.
 

·
The Entenmann's Shim-Sham
Joined
·
12,841 Posts
Make sure the lifter is on the base circle of the cam. Install the pushrod tool with teflon tape on the tool's threads. Torque the rocker to 22 ft-lbs, and then run the tool up until lash is taken out (the tool no longer wobbles up and down between the rocker and the lifter). Remove the rocker and carefully remove the tool so as to not accidentally turn it and mess up your measurement. Using 8" calipers, measure the length of the tool. Do not count turns or any other stupid method the broke-dick internet bros tout because they can't afford a $60 tool. Take that measurement, add your desired preload, and you have your needed length.
 
1 - 20 of 26 Posts
Top