Measuring push rod length with adjustable rockers???
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From: Little Rhody
Measuring push rod length with adjustable rockers??? Read all the information I could from a search but I still have some questions. Getting prepared for installing new heads and lifters in the spring. Here is my current setup:
Stock heads
Stock lifters
VHP Cam
Crane push rods
Crane adjustable rockers
I am going to install a set of Dart heads and I also want to install Morel lifters while the car is apart so here is the new setup:
Dart 205 heads
Morel lifters
VHP Cam
Crane adjustable rockers
Crane push rods, length TBD
So my question is, how do you verify the push rod length with the Crane adjustable rockers. I read the information on the Lunati web site, but their first step in the procedure is to install a solid lifter. Here is what I think needs to be done, please correct me if I am wrong.
1. Remove intake and exhaust spring on new heads, replace with checker springs
2. Install Morel lifters in checking locations
3. Install head on car using old gasket and tighten enough to remove clearances (around 15 lb-ft) Note I will be using stock GM gasket on the new heads.
4. Make sure intake is on base circle of cam, install checking push rod
5. Mark up top of valve with Sharpie
6. Install Crane rocker and finger tight to zero lash point
7. Rotate motor and check swipe, once correct then push rod length is established
Repeat the process on the exhaust valve.
I know what the swipe needs to look like, but what I don’t understand is if I need to be concerned with the lifter preload during this process, as I don’t think the checking spring will depress the lifter cup.
Does this look correct, or do I have some errors in my process?
Stock heads
Stock lifters
VHP Cam
Crane push rods
Crane adjustable rockers
I am going to install a set of Dart heads and I also want to install Morel lifters while the car is apart so here is the new setup:
Dart 205 heads
Morel lifters
VHP Cam
Crane adjustable rockers
Crane push rods, length TBD
So my question is, how do you verify the push rod length with the Crane adjustable rockers. I read the information on the Lunati web site, but their first step in the procedure is to install a solid lifter. Here is what I think needs to be done, please correct me if I am wrong.
1. Remove intake and exhaust spring on new heads, replace with checker springs
2. Install Morel lifters in checking locations
3. Install head on car using old gasket and tighten enough to remove clearances (around 15 lb-ft) Note I will be using stock GM gasket on the new heads.
4. Make sure intake is on base circle of cam, install checking push rod
5. Mark up top of valve with Sharpie
6. Install Crane rocker and finger tight to zero lash point
7. Rotate motor and check swipe, once correct then push rod length is established
Repeat the process on the exhaust valve.
I know what the swipe needs to look like, but what I don’t understand is if I need to be concerned with the lifter preload during this process, as I don’t think the checking spring will depress the lifter cup.
Does this look correct, or do I have some errors in my process?
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From: Little Rhody
But if I use the solid lifter, doesn't it in turn need to be set up so its lenght is that of the hydraulice lifter with the preset built in? In other words, when you do your final installation, you push in the plunger of the hydraulic lifter by say 0.060". If the hydraulic lifter is lets assume 2" long, I would need a solid lifter that is 2.000-0.060 or 1.940" long, correct? So what I then need is an adjustable lifter that is the length of the Morel including the lifter preload subtracted from the length?
Bought the Darts from Jason at TSP, he has them listed here somewhere.
Bought the Darts from Jason at TSP, he has them listed here somewhere.
Teching In
Joined: Dec 2005
Posts: 19
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It was a long night and an early morning. Brain starting to function now. You had it right mostly. I didnt see that you were using a checker spring either .The checker spring shouldnt depress the plunger. You dont worry about the swipe,thats used to check a solid lift, on the hydraulic you just tighten the rocker down until its snug then lengthen the adj. rod til its close.Then tighten the rocker slowly while spinning pushrod. you basicly just want it tight enough, without collapsing plunger, to stop the spinning motion thus zero lash. {try and get the length as close as you can by eye before starting}
Last edited by B_L_A_C_K_Z28; Dec 17, 2005 at 11:49 AM.
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Wouldn't you do that by starting with an available length of pushrod you think will work, shortening the adjustable by the preload you want, establishing zero lash, and then checking the swipe? Conversely, couldn't you find the length that gives you the best swipe pattern on the valve stem and simply add the amount of preload you want to that length? In other words, if you get the best pattern with a 7.30 inch pushrod at zero lash and you want .060 preload you would just add .060 to 7.30 which would give you a length of 7.36. Does that sound reasonable?
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From: Little Rhody
Yes, I spoke to both Crane and Manley tech support. They told me the same thing. Use the checking springs so I don't compress the lifter and get the swipe correct. Then add the preload to the length that provides the proper swipe.
What is interesting is I also call Comp Cams since it is their adjustable pushrod tool that I bought. Believe it or not he told me to not use the checking spring, but the valve spring. When I told him I thought it would further compress the lifter and I would get an erroneous answer, he told me to just guess the amount of additional lifter preload that occured!!!!
What is interesting is I also call Comp Cams since it is their adjustable pushrod tool that I bought. Believe it or not he told me to not use the checking spring, but the valve spring. When I told him I thought it would further compress the lifter and I would get an erroneous answer, he told me to just guess the amount of additional lifter preload that occured!!!!
Last edited by vettenuts; Dec 27, 2005 at 07:46 AM.
