Pushrod length help!

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danmc77

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Ok, finally getting all the things together on my 68 Charger. Got a new set of Eddy heads for the 440, and a new set of adjustable roller rockers. Now I need to measure for new pushrods, and I'm not sure how - I need help.

The cam is installed w/ all the lifters in place. I installed one head and torqued it down w/ a gasket in place. I also bought a trick-flow measuring push rod from Summit (ball/ball). No instructions included - nice.

So, I've read a few things from different companies, and all seem to have a different way of doing it.

Hughes engines wants you to pay $50 for a tester lifter to compensate for the amount of preload. Another link I read said to measure the dept of the lifters I'm using for my Hydro cam.

How is it done guys?

Also - do I need an oil-hole in the rod? They will have to be ball/ball, cause the rockers are very similar to the Comp rollers w/ the cup adjusters.
 
I guess you have adjustable rockers? If so measure from the lifter pocket without preloading the lifter to the bottom of the adjuster on the rocker with about 3-4 threads showing below the rocker. Then ad .040 to that number. Make sure the lifter is on the heal of the cam. That is how I measure them.
 
Also if your using shafts and havn't bushed you lifter holes than no you do not need push rods with oiling holes.
 
SGBARRACUDA said:
I guess you have adjustable rockers? If so measure from the lifter pocket without preloading the lifter to the bottom of the adjuster on the rocker with about 3-4 threads showing below the rocker. Then ad .040 to that number. Make sure the lifter is on the heal of the cam. That is how I measure them.
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So is the .040 accounting for the preload? Is that why you add it? In that case, that would mean that every rocker adjuster has to be dead on exactly the same, right?

What I mean is that if I measure using the intake and exhaust from one cylinder, and order the pushrods based off those figures, I would have to go through and adjust all the rocker adjusters to be exactly the same even before installing the new rods - otherwise the preload could vary from valve to vale, right?
 
For the record, I already tested the geometry in the #1 cyl valves - the roller tip pattern (used black marker) was right across the middle area of the valve tip, and at 50% lift, the rod and adjuster share the same plane. But now that I think about it, those tests were w/ the test rod adjusted to zero lash w/ no preload- I'm confused - if I add the .040, will that throw the geometry off significantly?

Do I need to test this with every valve? I did the intake and exhaust of the #1 cyl.
 
Dan,

If you want to go anal on this, test all 4 corners... I never do that.

Test one from each bank. Get it to 0 lash, add desired preload to length. You won't get the adjuster to all be exactly X turns out. Ain't gonna happen and # of turns out is a suggested point that you want to stay close. It's a good starting point..

Don't over think it. It's a pretty straight forward process.

Hope you are well.
 
crackedback said:
Dan,

If you want to go anal on this, test all 4 corners... I never do that.

Test one from each bank. Get it to 0 lash, add desired preload to length. You won't get the adjuster to all be exactly X turns out. Ain't gonna happen and # of turns out is a suggested point that you want to stay close. It's a good starting point..

Don't over think it. It's a pretty straight forward process.

Hope you are well.
Click to expand...
Thanks Rob. It seems pretty damn simple to me, but when I keep reading all the info on the web, they're talking about compensating for the friggin' oil hole chamfer on the end. It makes me think I'm not being accurate enough.

Do you agree with the .040 preload #, or would that be something I would find on my cam card? It's a Hughes cam.
 
.040 is fine. I run my hyd rollers at .010, but, it's stinking noisy!

Might call hughes for a suggested preload.
 
If these are the "Cat" stainless rockers make sure they have the bronze bushings and then if you look at one of the "adjuster" screws you will notice that they have a undercut{missing threads} about 1/3rd of the way up. When you make your mesurement be sure that the "undercut" is centered in the body of the rocker as this is where the oil is fed to the push rod end. Most aftermarket pushrods will be hollow to alow "pushrod" oiling and this will help also. Don't be afraid of to much oil in the topend as oil is what cools the springs and cool springs last longer.
For my "360" I found that "GM Ls1" poushrods were the Ideal length. 7.40" of corse every engine is a little diffrent.
 
Since your rocker to valve geometry is good the push rod length will have NO effect on that given it is a shaft system.

So the only two things you have to worry about is lifter pre-load and the oil hole alignment in the rocker arm body to rocker adjuster. Take the adjuster out of the rocker arm and you will see how that hole aligns allowing oil to flow to the top of the push rod tip. I just tested one cylinder on mine and got the pre-load and adjuster alignment where I wanted it then took the push rod length checker to a local machine shop and they measured it for me. Then I ordered accordingly. I went with Comp Cams hollow push rods for extra oiling.

I run .030" pre-load on mine which is on the high side for a performance application but I don't want to mess with adjusting them all the time.
 
Great guys - I'm off today and measuring away! Hope to have the Charger up and runnng again in a couple of weeks - can't friggin' wait.

Thanks for all the help!

Edit: BTW, I guess I would consider this a "performance build," It's a stock stroke, .060 over 440, w/ 75cc Eddy heads (corrected valve job), gasket matched, Machined for Hughes springs, Hughes cam (237*/242* .547/.555 lift), Roller rockers, RPM intake, Demon 850 carb, around 10.5:1 cr, Mallory unilite dist, mallory ign box, windage tray, hi-flow oil pump, etc.

4 speed.

is .040 preload too much?
 
I know it's not an A body (my Demon is my next project), but figured you guys might like to see what it is that I'm working on.

I know - my garage is a mess, and the car hasn't been washed in over a year, and the engine needs some paint touch-up, so...

IMG_2641.jpg

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Thanks for the help guys - got the pushrods in the mail 2 days ago. Got one side all set up with the rockers aligned and torqued. Going to Carlise tomorrow for some odds and ends - should be cruising around in this 500+hp baby in the next couple weeks!
 
ah my eyes... an infidel B body!!! :-D

Nice looking car.
 
we love looking at pictures. nice car. dont fret the little things. she looks like she,s coming along just fine.
 
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