When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I am in the middle of my AA supercharger install and recently installed my cam / valve springs / trunnion kit. I need some help measuring the pushrod length though. 2004 Z06, LS6, with about 20k miles on the clock.
I bought a comp cam pushrod length checker to perform the measurements. I watched several videos on how to "finger tighten and count the socket / ratchet turns by hand" but this seemed subjective and I kept getting different turn counts.
I had already purchased some Tick 7.400" / .080 hardened rods which came with the cam kit (with the understanding I may need different ones).
Turns: this is the number of turns on the 6.8" comp cam tool (1 turn = 0.05")
Measurement: I pulled the tool out of the engine and measured the length with calipers
This measurement table
6.8" + (tool turns x 0.05")
So my question is what length pushrod should I run? Now I have not added anything lifter related in these measurements.
Also I'm not sure if this is the correct way to measure with calipers, but is there a reason why the 7.400" pushrods measure longer?
I've been searching the forums and to keep it simple, will use the pushrod tool turn method to calculate the pushrod needed.
So based on this table:
Now the pushrods I have currently are Tick 7.400"
This would give me somewhere between 0.0625" - 0.0875" preload on the stock LS6 lifters. Does this sound appropriate? I don't know what the plunger travel is on the stock LS6 lifters.
Now I wasn't planning to change the lifters with this build but wondering if I should just go ahead and pull the heads and do new trays / lifters / headgaskets / ARP bolts / etc...?
While you're in there! (the fire scariest words in hotrodding). If you change the lifters, you need to change the trays, and you'll need new head gaskets, the LS9's are a forum favorite. ARP stuff is really up to you, do you plan on going FI at all? Power levels? They are reusable, so thats another selling point. Stock head bolts are one time use only.
I recently went through this on my build as well. I measured mine to where there was no lash on the rocker with the comp cams pushrod tool, then I added my lifter preload to that number and I to am running 7.4 pushrods on my build. The reason the 7.4’s run longer is because of the ball end at each end of the pushrod is not measured from the manufacture because the ball end sits inside the rocker and in the plunger of the lifters. I’m guessing we’ve watched most of the same videos and your measuring on the base circle of the camshaft. Not always the case but if you don’t change the base circle size the pushrods will almost be the same as OE. (Head gasket thickness, milled heads, and different lifters can effect this though)
While you're in there! (the fire scariest words in hotrodding). If you change the lifters, you need to change the trays, and you'll need new head gaskets, the LS9's are a forum favorite. ARP stuff is really up to you, do you plan on going FI at all? Power levels? They are reusable, so thats another selling point. Stock head bolts are one time use only.
Scary words for sure lol. I feel like if I start pulling the heads to do the lifters, I may as well commit to a forged build since most of the motor is already pulled apart. I am currently installing a V3Ti AA kit / 3.6" pulley right now but think I will wait to do lifters. Hopefully the stock ones hold up and I don't have issues with a conservative tune / meth for cooling.
Originally Posted by ls_lando
I recently went through this on my build as well. I measured mine to where there was no lash on the rocker with the comp cams pushrod tool, then I added my lifter preload to that number and I to am running 7.4 pushrods on my build. The reason the 7.4’s run longer is because of the ball end at each end of the pushrod is not measured from the manufacture because the ball end sits inside the rocker and in the plunger of the lifters. I’m guessing we’ve watched most of the same videos and your measuring on the base circle of the camshaft. Not always the case but if you don’t change the base circle size the pushrods will almost be the same as OE. (Head gasket thickness, milled heads, and different lifters can effect this though)
Thanks that makes sense now. Since the car is down right now for the supercharge install, waiting on parts, etc...I was able to did double check all of the measurements on the base circle. As far as I know, Tick did not change the base circle size on this cam, so I think the 7.4s will be good with the preload range I calculated. There def is no lash when I checked.
Is it normal for the motor to be harder to turn over by hand as the pushrods / valves move up and down? The plugs are still removed and it doesn't make any noise, just tougher as the springs are compressed.
I've found that It's not so much the camshaft that will cause the different lengths in PR's between the intake and exhaust but more so the valves. Most of the time you can lay a straight edge accross the valves on the cylinder heads and all of them will be even but not always the case.
[QUOTE=pianoman90;20432493]Scary words for sure lol. I feel like if I start pulling the heads to do the lifters, I may as well commit to a forged build since most of the motor is already pulled apart. I am currently installing a V3Ti AA kit / 3.6" pulley right now but think I will wait to do lifters. Hopefully the stock ones hold up and I don't have issues with a conservative tune / meth for cooling.
Thanks that makes sense now. Since the car is down right now for the supercharge install, waiting on parts, etc...I was able to did double check all of the measurements on the base circle. As far as I know, Tick did not change the base circle size on this cam, so I think the 7.4s will be good with the preload range I calculated. There def is no lash when I checked.
Is it normal for the motor to be harder to turn over by hand as the pushrods / valves move up and down? The plugs are still removed and it doesn't make any noise, just tougher as the springs are compressed.[/QUOTE
Yes, it's normal. You're trying to overcome a lot of friction and spring tension!!! Now you know why roller lifters and roller rockers make more power (and less heat) through less friction in the valvetrain.....
You mention using "Straub bronze trunnion upgrade"... I hope that you are the type that is extremely consistent on maintenance. Those bushings will require rocker arm removal, and pressing them apart to inspect the INNER DIAMETER of the bushing at least every 20K miles, or sooner. Look up the posts here on this web site detailing the failure of those specific bushings. I had a set fail at 12K miles. Others have pulled them apart at +/- 20K miles and found theirs worn.. Others have gotten much further and just have not checked them for wear by disassembly. Notice, I'm not saying "DON'T USE THOSE!". I'm simply advocating for the required maintenance that comes along with them. If I were to run them again, I'd be pulling them apart every 10K miles and measuring the ID, and also visually inspecting them for scoring. The other thing you can do is check your engine oil at every oil change for BRONZE glitter in the oil. If you see that.. you'll then know what's up.
T&D steel rollers on the 01 here but I do have a set of LS7 rocker arms with Straub bronze bushings with about 10K on them. I'm not finding anytinhg about bushing failures on LS1Tech but there's plenty of stuff out there on the CompCams trunnions. I had some I was using with a .660 lift cam and noticed issues with those before reaching 5K.
https://ls1tech.com/forums/generatio...e-failure.html https://ls1tech.com/forums/generatio...on-kits-2.html https://ls1tech.com/forums/generatio...s-engines.html https://ls1tech.com/forums/generatio...stroyed-3.html and this one I was the original OP.. I DO HAVE PICTURES of all 16 damaged bushings if anyone would care to see them. At the time of my issues, as you can see from the post, MANY people were blaming me for the failure of the bushings........ Instead of turning it into a poo slinging event, I simply moved on with my life and bought new rockers from Summit with the upgraded trunion bearings already installed. Look at the date of that thread.. I have NOT had any problems with the SUMMIT upgraded trunion rockers since then... and made NO other changes to the engine except swapping out the rocker arms with the bushings in them. .... But... please... take a moment and look at those people that attacked ME... Just because I posted about my experience... and now... there are more reported cases of other people having similar issues with the bronze bushings... I don't want to harm your post as I know you are just wanting information. I'll leave it at the links above..
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.
7 Most Reliable High-Performance Engines GM Has Ever Built
Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.
Help measuring pushrod length - LS6 / 04 Z06 
