1QuickT-A

iTrader: (12)

I'm about to order my pushrods which is the last item on my list before I sit the motor in the car. How would you guys recommend that I check for the correct length? I already have a pushrod length checker from Comp. Here is a parts breakdown as well..

AFR 225s milled to 65cc (spring upgrade)
Comp 246/254 .613/.613
Jesel SS non adjustable shaft mounts
Comp replacement lifters
6.0 Iron block
.062 copper gaskets

Thanks for your input!

PREDATOR-Z

do you have valve reliefs?
As for p-rods i would say at least 7.425s and perhaps 7.450 (depending on gasket used)

1QuickT-A

iTrader: (12)

Yeah the valve reliefs are around 4cc's... I figured the pushrods would be around 7.5 or close to it. What is the best "technique" as far as using the pushrod tool to check the length?

ShevrolayZ28

iTrader: (4)

Easy. Make sure the cam is at it's low point and that the lifter is on the cam and not just hanging in it's bore. Make sure that the lifter's plunger is at it's full travel position. Drop the tool in there and make sure the rubber band is positioned such that it keeps the bottom of the tool form turning. Install the rocker and then, by hand, unscrew the pushrod tool until it just takes up the length between the lifter and the rocker (zero lash). Remove the rocker, then carefully remove the tool and count how many turns were required to make up the length. Add your desired lifter preload to the length of the tool and you're done.

Ferocity02

iTrader: (60)

That's right on, exactly how I did it. Except, instead of counting turns, I measured the length of the pushrod with a dial caliper. A little more accurate IMO. I think counting turns is kind of a crude way to do it. But whatever works, stock lifters are fairly lenient in terms of preload.

ShevrolayZ28

iTrader: (4)

I think the tool is plenty accurate. And besides, my verniers won't measure something that long.

BlkHwk

iTrader: (8)

I am fixing to measure mine hopefully tomorrow. I plan to measure the lower portion of the pushrod, measure the upper portion and then the adjustable portion (middle) and then add em together.

What's with the rubber band tho? I have the comp adjustable pushrod but didn't get any instructions with it.

ShevrolayZ28

iTrader: (4)

The rubber band ends up snug between the head and the pushrod. This way it holds the lower half of the tool in place so that it doesn't turn with the upper half as you're taking up the length. You'll see what I mean when you go to it.

1QuickT-A

iTrader: (12)

Just now got to read all of these responses.. Thanks fellas!

I did some testing earlier and it looks like I'm gonna need a 7.375 as far as I can tell.. I just used the old school method.. I pumped the lifter all the way up and made sure it was on the cam lobe. Then I sat the pushrod in the hole and test fitted the rocker arm. After 2-3 times I had it just about right. So on the final try I adjusted the pushrod out a little longer, dropped it in, bolted down the rocker arm, and spun the pushrod with my finger. There is no play in the rocker arm from side to side or up and down. The pushrod is nice and snug with no play up/down or side to side..

Should I add more for lifter preload? I don't want to get them to tight and kill my lifters and/or cam.

1989GTA

If you know the length of the adjustable pushrod when it is fully closed that is all you need to get started. When you find the correct length just measure the now exposed threaded portion of the pushrod with your dial calipers and add that to the closed length.

1QuickT-A

iTrader: (12)

Hell I just used a damn tape measure.. lol

ShevrolayZ28

iTrader: (4)

Good to hear that you made some progress.

How much preload did you add? And how long was the tool at zero lash?

PS I don't think it's a good idea to turn the motor over with the pushrod tool installed, unless you have a checker spring installed.

1QuickT-A

iTrader: (12)

I only turned the motor over 1 time with it installed just to be sure the valve was closed and the lifter was pumped all the way up..

I haven't added any for lifter preload yet.. It measured 7 3/8ths at zero lash which converts to 7.375 I believe. What should I add for preload?

ShevrolayZ28

iTrader: (4)

You're kidding. Aren't you?

Read below, it might help.

I forgot to mention a couple things. Once you have unscrewed the pushrod to zero lash you are ready to determine which length pushrod you need. There's no need to take any more measurements.

The Comp Cams pushrod length checker is 6.800" long when at it's shortest. Each full turn is 0.050". Add the number of turns, each worth 0.050", to 6.800", and then add your desired preload, which is between .050"-.120" for stock style lifters IIRC.

6.800" + (.050"-0.120") + number of turns = pushrod length

ShevrolayZ28

iTrader: (4)

You shouldn't turn the motor over. Not only might it damage the tool, but you might have depressed the lifter plunger, which would cause you to get an inacurate measurement.

1QuickT-A

iTrader: (12)

No I'm really not kidding.. A tape measure was used in the testing of this procedure..

I dont have anything else here at my house to use. I will count the number of turns tomorrow and see what I come up with. And I will call a friend to borrow his calipers as well.

1QuickT-A

iTrader: (12)

The lifter plunger is not depressed... With the pushrod in place and the rocker arm bolted down you can hold the roller tip of the rocker arm and pull it up and feel the resistance of the plunger as you pull up. Then let go and the rocker arm slaps back against the valve stem firmly.

ShevrolayZ28

iTrader: (4)

If you did a good measurement with the tape measure it might be close enough lol. But do check it out tomorrow and see what you get by adding up the number of turns. Good luck.

Boodyrider

iTrader: (2)

Comp makes two length checkers, the expensive one IS .050 per turn AND is marked.

PREDATOR-Z

If you determined 7.35 at 0 lash, then add .080 preload (average) and you got 7.455
so like i said either 7.425 or 7.450 (choose your poison)