The famous pushrod length question...
Thread Starter
TECH Fanatic
Joined: Aug 2008
Posts: 1,740
Likes: 2
From: Nebraska
The famous pushrod length question... Okay guys, i've read and read and see so many different things when it comes to measuring pushrods and I need some clarification...
I have a CC503, Comp Pro Mag rockers, 918 springs etc etc. This is the method I was going to use, please correct me if i'm wrong.
I'm using a stock lifter that modified to be solid, I have the comp cams adjustable pushrod checker. So I will set the pushrod to 7.200" to start, tighten my poly lock until I hit zero lash and stop. I will rotate the motor over a few times, pull the rocker back off and check the contact patch of the rocker on the valve stem. If it favors the exhaust side, I will want to shorten the pushrod to 7.150" for example and try again. If it ends up in the middle of the valve tip, that 7.150" is the size I need to order correct? So at this point, do I need to account for preload? Does that add length to the pushrod? If I were to get a 7.150" pushrod, wouldn't it be too short once I add preload? That's where i'm confused.
I have a CC503, Comp Pro Mag rockers, 918 springs etc etc. This is the method I was going to use, please correct me if i'm wrong.
I'm using a stock lifter that modified to be solid, I have the comp cams adjustable pushrod checker. So I will set the pushrod to 7.200" to start, tighten my poly lock until I hit zero lash and stop. I will rotate the motor over a few times, pull the rocker back off and check the contact patch of the rocker on the valve stem. If it favors the exhaust side, I will want to shorten the pushrod to 7.150" for example and try again. If it ends up in the middle of the valve tip, that 7.150" is the size I need to order correct? So at this point, do I need to account for preload? Does that add length to the pushrod? If I were to get a 7.150" pushrod, wouldn't it be too short once I add preload? That's where i'm confused.
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
if you use a "solid" lifter than it won't compress as a hydraulic would when you add "pre-load" from lash.
With that said I do exactly as you described in using a PR check tool and adjusting until the witness mark is dead center and as narrow a sweep as possible.
7.150 and 7.100 are VERY common results with a H/C swap
I have not tried but there is a Proform PR length tool that is used once spring is installed and PR (without RR). This would mean it is used with no pre-load on a lifter.
http://www.summitracing.com/parts/pro-66790
this one is for 7/16 RR studs. They make it for 3/8" also
With that said I do exactly as you described in using a PR check tool and adjusting until the witness mark is dead center and as narrow a sweep as possible.
7.150 and 7.100 are VERY common results with a H/C swap
I have not tried but there is a Proform PR length tool that is used once spring is installed and PR (without RR). This would mean it is used with no pre-load on a lifter.
http://www.summitracing.com/parts/pro-66790
this one is for 7/16 RR studs. They make it for 3/8" also
Thread Starter
TECH Fanatic
Joined: Aug 2008
Posts: 1,740
Likes: 2
From: Nebraska
Thread Starter
TECH Fanatic
Joined: Aug 2008
Posts: 1,740
Likes: 2
From: Nebraska
if you use a "solid" lifter than it won't compress as a hydraulic would when you add "pre-load" from lash.
With that said I do exactly as you described in using a PR check tool and adjusting until the witness mark is dead center and as narrow a sweep as possible.
7.150 and 7.100 are VERY common results with a H/C swap
I have not tried but there is a Proform PR length tool that is used once spring is installed and PR (without RR). This would mean it is used with no pre-load on a lifter.
http://www.summitracing.com/parts/pro-66790
this one is for 7/16 RR studs. They make it for 3/8" also
With that said I do exactly as you described in using a PR check tool and adjusting until the witness mark is dead center and as narrow a sweep as possible.
7.150 and 7.100 are VERY common results with a H/C swap
I have not tried but there is a Proform PR length tool that is used once spring is installed and PR (without RR). This would mean it is used with no pre-load on a lifter.
http://www.summitracing.com/parts/pro-66790
this one is for 7/16 RR studs. They make it for 3/8" also
TECH Addict
Joined: Dec 2010
Posts: 2,610
Likes: 4
From: Maricopa, AZ
Sweep area is more important than sweep location. Within reason of course. A small sweep favoring the exhaust is better than a large sweep over the center. At mid lift you want the rocker perpendicular to the cylinder bore. This will put the highest and lowest point of the rocker at the same point on the valve and give you your best sweep. If that puts your sweep area too close to the valve stem edge adjust the pushrod length to bring it closer to center.
Trending Topics
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
Okay I think I understand now, preload doesn't play a part in pushrod length? Whatever I measure with a solid lifter and the rocker set at zero lash and the rocker tip being centered on the valve tip, should be the length I need correct? Preload is just slightly compressing the lifter for a "cushion" and quieter operation basically?
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
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 Thread Starter
TECH Fanatic
Joined: Aug 2008
Posts: 1,740
Likes: 2
From: Nebraska
Okay I think I understand now, preload doesn't play a part in pushrod length? Whatever I measure with a solid lifter and the rocker set at zero lash and the rocker tip being centered on the valve tip, should be the length I need correct? Preload is just slightly compressing the lifter for a "cushion" and quieter operation basically?
Thats a fact jack. Youve been post'n here for decades, trying to give others advice and u didnt even know the difference between a solid lifter and a hydrualic. And now your so far ahead of yourself u dont even know it.
The most accurate method is done at mid-lift with the rocker geometry perpendicular. But your so clueless it would be a waste of time for u.
U keep practicing half-azz, hick mechanic habits u read on the internet from sloppy amateurs. Then u attack others when they post factual information and methods.
U think u know more than using a simple p-rod length checker so u try some hack method trying to fool the uniformed u have a more accurate method.
Thx for posting, now we can see how little u know.
Thats a fact jack. Youve been post'n here for decades, trying to give others advice and u didnt even know the difference between a solid lifter and a hydrualic. And now your so far ahead of yourself u dont even know it.
The most accurate method is done at mid-lift with the rocker geometry perpendicular. But your so clueless it would be a waste of time for u.
U keep practicing half-azz, hick mechanic habits u read on the internet from sloppy amateurs. Then u attack others when they post factual information and methods.
U think u know more than using a simple p-rod length checker so u try some hack method trying to fool the uniformed u have a more accurate method.
Thx for posting, now we can see how little u know.
You have to be the biggest douchebag on the internet. I help a lot of other people out but have never offered advice on pushrod length because I was never sure so I asked for help and got it, thats what a forum is for you ******* troll. I help people with stuff I know, I try not to give bad info. You have proven on every forum you've been on that you are completely full of yourself and believe your **** don't stink, and go to extreme lengths to prove you think you know what you are talking about, only to get shut down by people much more knowledgeable than you.
And two things, #1 Where the hell did I say I don't know what the difference between a hydraulic lifter and a solid lifter is? I took a hydraulic lifter and shimmed it so it was solid and took the measurements with my comp cams pushrod length checker, I don't know what the hell you were reading but I never said anything about not knowing the difference. There is nothing "hick" about what I was doing #2 I've been on this forum for decades huh??? You must not be too smart since I only joined in 2008 when I was 18, if your little brain can do the math that's less than 7 years...
I don't know where you got the audacity to come into my thread just to say that garbage you did but you sir can **** off.
TECH Resident
Joined: Jun 2013
Posts: 853
Likes: 32
From: Kernersville, NC
LoL, like you have room to talk.
The fun starts around post #25.
http://www.camaroz28.com/forums/lt1-...rances-868738/
...and not long after that he signed up here.
The fun starts around post #25.
http://www.camaroz28.com/forums/lt1-...rances-868738/
...and not long after that he signed up here.
Last edited by ACE1252; Feb 18, 2015 at 02:44 PM.
You have to be the biggest douchebag on the internet. I help a lot of other people out but have never offered advice on pushrod length because I was never sure so I asked for help and got it, thats what a forum is for you ******* troll. I help people with stuff I know, I try not to give bad info. You have proven on every forum you've been on that you are completely full of yourself and believe your **** don't stink, and go to extreme lengths to prove you think you know what you are talking about, only to get shut down by people much more knowledgeable than you.
I can dole out advice and how to videos on everything from alternators to 5.3L swaps, but if you ask me about checking pushrod length, valve spring height, or degreeing a cam, I won't have an answer.
I have far more respect for the guy that asks questions and learns from them, then I do for the loudmouth that tries to point out other people's flaws to make himself look better.
LoL, like you have room to talk.
The fun starts around post #25.
http://www.camaroz28.com/forums/lt1-...rances-868738/
...and not long after that he signed up here.
The fun starts around post #25.
http://www.camaroz28.com/forums/lt1-...rances-868738/
...and not long after that he signed up here.
I think this quote by Debler needs to be permanently inserted into cardo0's signature:
Books are for reference. That's why they go in the "Reference" section of libraries and book stores. Technology changes. Materials change. Theories change. A book can never accommodate this, but real-word experience can and does. That is why sites like this one exist.
Thread Starter
TECH Fanatic
Joined: Aug 2008
Posts: 1,740
Likes: 2
From: Nebraska
I saw that quote too, definitely a lot of truth to it.
TECH Resident
Joined: Jun 2013
Posts: 853
Likes: 32
From: Kernersville, NC
Same BS time and time again from you. Spreading misinformation and trolling whenever you get called out for being wrong.
Last edited by ACE1252; Feb 22, 2015 at 02:29 AM.
TECH Enthusiast
Joined: Jul 2007
Posts: 563
Likes: 0
From: Central,NJ
From what I've seen in the past couple years...I think you deserve to hand off that title. Though, Richard will be missed by all
Let us stop for a second and consider the basic architecture we are working with was born in the 50s with sub-.400 lift, eventually GM was using a bit more but most OEM cams for the gen 1-2 architecture are say .470 and under. We are talking about setting stuff up way way outside the range this architecture was designed for.
Which is why you have folks saying narrowest sweep is unlikely to be center, we are asking it to handle things well outside what GM designed it for. In a perfect world the pattern would be center and narrow, but since we are using different ratio rockers and 35%+ more lift than the original architecture it just isn't going to happen.
I also think folks get far too worked up over it, the valvetrain is adjustable afterall.
Basically pick what you feel is best be it center or narrow or some balance of the two and run with it. The valvetrain is again adjustable.
Only time I have ever heard of pushrod length induced damage in an LT1 was a checkbook mechanic put in pushrods so long he ran the roller tips off the edge of the valve tip and RAN IT busting a bunch of the guides!
Long as you are conscience of pattern width and location on valve I think you will do just fine.
Non adjustable valvetrain like the LS1 variants are going to be more sensitive and I think people hear about that and presume the same level of sensitivity applies to this application. IMO it does not.
Which is why you have folks saying narrowest sweep is unlikely to be center, we are asking it to handle things well outside what GM designed it for. In a perfect world the pattern would be center and narrow, but since we are using different ratio rockers and 35%+ more lift than the original architecture it just isn't going to happen.
I also think folks get far too worked up over it, the valvetrain is adjustable afterall.
Basically pick what you feel is best be it center or narrow or some balance of the two and run with it. The valvetrain is again adjustable.
Only time I have ever heard of pushrod length induced damage in an LT1 was a checkbook mechanic put in pushrods so long he ran the roller tips off the edge of the valve tip and RAN IT busting a bunch of the guides!
Long as you are conscience of pattern width and location on valve I think you will do just fine.
Non adjustable valvetrain like the LS1 variants are going to be more sensitive and I think people hear about that and presume the same level of sensitivity applies to this application. IMO it does not.