How do you measure for correct push rod length?
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
How do you measure for correct push rod length?
I got my new used heads for my old 406.. (bought those heads off Ebay) I'll have them checked for any issues by a machine shop next week before I'll install them. They are RHS (Pro Topline) 235 cc heads which were FULLY ported and cut (milled) to 56 cc. They have .750 lift dual springs on them with titanium retainers. (Valves are 2.08/1.60)
Now I wonder if I'll be able to use the pushrods that I used in combination with my Dart Pro 1 heads (which also had been cut to 56 cc). However, my Dart Pro 1 heads had .700 lift dual springs, so the spring height might be different.
How do I determine how long the pushrods have to be for ideal geometry???
Now I wonder if I'll be able to use the pushrods that I used in combination with my Dart Pro 1 heads (which also had been cut to 56 cc). However, my Dart Pro 1 heads had .700 lift dual springs, so the spring height might be different.
How do I determine how long the pushrods have to be for ideal geometry???
Last edited by GrandSportC3; May 4, 2007 at 11:21 AM.
Melting Slicks
Joined: Aug 2004
Posts: 2,165
Likes: 950
From: Keizer Oregon
Ah! I just went throught his same thing. I got an adjustable pushrod length checker. I picked the number one cylinder and set up my rockers/studs/valves using the adjustable pushrod. You want to have the roller rocker "centered" over the valve stem at 1/2 valve lift. the total travel of the rocker bearing over the valve stem should stay in the middle 1/3 of the stem. Also the geometry of the stud/pushrod should be as close to parallel as possible.
There are some pretty good reads online...I will see if I can recall the links.
Good Luck.
http://www.compcams.com/information/Products/Pushrods/
http://www.circletrack.com/techarticles/1814/
There are some pretty good reads online...I will see if I can recall the links.
Good Luck.
http://www.compcams.com/information/Products/Pushrods/
http://www.circletrack.com/techarticles/1814/
Last edited by oregonsharkman; May 4, 2007 at 11:47 AM.
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Ah! I just went throught his same thing. I got an adjustable pushrod length checker. I picked the number one cylinder and set up my rockers/studs/valves using the adjustable pushrod. You want to have the roller rocker "centered" over the valve stem at 1/2 valve lift. the total travel of the rocker bearing over the valve stem should stay in the middle 1/3 of the stem. Also the geometry of the stud/pushrod should be as close to parallel as possible.
There are some pretty good reads online...I will see if I can recall the links.
Good Luck.
http://www.compcams.com/information/Products/Pushrods/
http://www.circletrack.com/techarticles/1814/
There are some pretty good reads online...I will see if I can recall the links.
Good Luck.
http://www.compcams.com/information/Products/Pushrods/
http://www.circletrack.com/techarticles/1814/
Melting Slicks
Joined: Aug 2004
Posts: 2,165
Likes: 950
From: Keizer Oregon
Le Mans Master
Joined: Oct 2004
Posts: 5,269
Likes: 54
From: Orlando Florida
St. Jude Donor '05
I'm pretty sure that with .700" lift you're using solid lifters.... hydraulic lifters must be shimmed "solid" to measure pushrod length.
I adjusted my adjustable pushrod checking tool to 7.400" and installed a solid lifter, adjusted the rocker arm nut and rotated the crank two turns. I had black Sharpie ink on the valve tip, after two crank rotations there was a shiny stripe right at the center of the valve tip indicating that the pushrod length is correct.
I adjusted my adjustable pushrod checking tool to 7.400" and installed a solid lifter, adjusted the rocker arm nut and rotated the crank two turns. I had black Sharpie ink on the valve tip, after two crank rotations there was a shiny stripe right at the center of the valve tip indicating that the pushrod length is correct.
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Melting Slicks
Joined: Aug 2004
Posts: 2,165
Likes: 950
From: Keizer Oregon
Racer
Joined: Jan 2005
Posts: 332
Likes: 7
From: In the shop most of the time,,, And it BEER TIME somewhere
Hey Oliver also check this link, This is a handy tool to check pushrod lenght, http://www.speedwaymotors.com/p/536,...h-Checker.html
Racer
Joined: Jan 2005
Posts: 332
Likes: 7
From: In the shop most of the time,,, And it BEER TIME somewhere
Hey Oliver also check this link, This is a handy tool to check pushrod lenght, very easy to use. http://www.speedwaymotors.com/p/536,...h-Checker.html
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
I'd think a Sharpie would maybe not rub off as well as it should to give you a good pattern.
I'd get a bottle of machinists' dye.. Dykem? I think it is. Dark blue, and will leave a coat so thin you can scratch it with a fingernail.
I don't know, maybe a SHarpie will too? Not trying to rain on a parade, I'm just asking here.
I'd get a bottle of machinists' dye.. Dykem? I think it is. Dark blue, and will leave a coat so thin you can scratch it with a fingernail.
I don't know, maybe a SHarpie will too? Not trying to rain on a parade, I'm just asking here.
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Hey Oliver also check this link, This is a handy tool to check pushrod lenght, http://www.speedwaymotors.com/p/536,...h-Checker.html
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
I'd think a Sharpie would maybe not rub off as well as it should to give you a good pattern.
I'd get a bottle of machinists' dye.. Dykem? I think it is. Dark blue, and will leave a coat so thin you can scratch it with a fingernail.
I don't know, maybe a SHarpie will too? Not trying to rain on a parade, I'm just asking here.
I'd get a bottle of machinists' dye.. Dykem? I think it is. Dark blue, and will leave a coat so thin you can scratch it with a fingernail.
I don't know, maybe a SHarpie will too? Not trying to rain on a parade, I'm just asking here.
I could not live without Dykem Bluing.
Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
I'm pretty sure that with .700" lift you're using solid lifters.... hydraulic lifters must be shimmed "solid" to measure pushrod length.
I adjusted my adjustable pushrod checking tool to 7.400" and installed a solid lifter, adjusted the rocker arm nut and rotated the crank two turns. I had black Sharpie ink on the valve tip, after two crank rotations there was a shiny stripe right at the center of the valve tip indicating that the pushrod length is correct.
I adjusted my adjustable pushrod checking tool to 7.400" and installed a solid lifter, adjusted the rocker arm nut and rotated the crank two turns. I had black Sharpie ink on the valve tip, after two crank rotations there was a shiny stripe right at the center of the valve tip indicating that the pushrod length is correct.
So you put in the modified lifter, assemble everything, use an adjustable pushrod and determine for the sake of arguement that the pushrod length should be 7.400. Now you install the hyd lifter, put in your new pushrod at 7.400 and snug the rocker to the pushrod..........then you give it 1/2 or 3/4 turn to set the adjustment on the lifter. That now puts the pushrod down inside the lifter collapsing the spring, effectively changing the pushrod length.
Does the lifter stay in that relative position after it's set or does the oil pressure bring up the seat in the lifter to the top so it resembles the solid one thereby restoring the correct geometry?
Bill
Le Mans Master
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I have tried the dye or sharpie or whatever, it is a waste of time, if you can't see the travel with your eyeballs somethings wrong 
Pro
Joined: Jan 2002
Posts: 624
Likes: 0
From: Marietta ga
I'd think a Sharpie would maybe not rub off as well as it should to give you a good pattern.
I'd get a bottle of machinists' dye.. Dykem? I think it is. Dark blue, and will leave a coat so thin you can scratch it with a fingernail.
I don't know, maybe a SHarpie will too? Not trying to rain on a parade, I'm just asking here.
I'd get a bottle of machinists' dye.. Dykem? I think it is. Dark blue, and will leave a coat so thin you can scratch it with a fingernail.
I don't know, maybe a SHarpie will too? Not trying to rain on a parade, I'm just asking here.
