Trying to determine if my pushrods are the correct length.

I have Thunder Racing chromoly 7.200" push rods. These rods appear to be about .020 longer than bone stock pushrods.

I am using Comp Cams 1.6 ratio Pro-mags on stock valved heads with LT4 valve springs.

I did the sharpy marker test with 1/4 turn past zero lash and this is what I get.


The pattern that I see clearly is not in the center. It is shifted down toward the exhaust side of the valve stem.

It appears that I need 7.150" push rods.
Any suggestions?

 

Might want to pick up a pushrod length checker. Less then $20 and it'll save some agrivation. I needed a 7.100" pushrod with my setup.

 

Yup, gonna do that and be done with it.

 

Ya also have to do it with a solid lifter not a hyd.

 

Is there a particular solid lifter?
I hope I can buy a single lifter in order to do this?

I guess common sense would say tha even if the lifter was a tad collapsed and I still have a low pattern then clearly the pushrods are too long and I am going in the right direction.

I am going to get the adjustable pushrod, is there another way to determine the correct length?

 

Yep.

And you can buy a single solid lifter. I remember this coming up in a post a while back.

 

Any chance of getting a part number. The search is hosed right now.

 

Ya don't have to buy anything.
Take one of your hyd lifters apart,cut a 3/8" bolt and grind it until the cap and lock just go back on. Walla--- solid lifter.
There is nothing to taking it apart but ya may have a time getting the inner chamber out due to oil suction. Keep it clean and when ya put it back together make sure it's SPOTLESS.

 

Good info here:
http://www.mid-lift.com/TECH/TECH-Installed-G1.htm

You click the big pic at the top of the page and it will bring you to the next page.

 

DAVE,
Most people will get totally confused by that sight. VERY good info but ya have to take the time to understand it and what he is saying.
There is SO MUCH info that most won't take the time and come away with part of the equation which is more dangerous yet.

 

Good point. I thought it was pretty good after I read it over 5 or 6 times.

 

I am not going to gut the lifter and take a chance, maybe I can find a used one from someone and do the mod.

Someone please explain this.
If you look at the photo it is obvious that the pushrod is too long. If the lifter was collapsing during the test then the mark would be a lot higher on the valve stem. It almost appears that the lifter is not collapsing.
To perform the test I am cranking the motor over using the starter, maybe this is pumping up the lifters.

I tested the same two valves several times with consistant results.

Am I way off here?

 

Just not the way it is done.
To answer your question-- don't know cause that's not the way or even close to the way I have done it for the last 40 years.Have had no experience doing it that way.
A pair of solid rollers will run ya 60-70 dollars new.

 

I had to do the same thing then chuckled as the way they are doing it is the way I was shown 35/40 years ago by Bruce Crower.

 

Please dont think I am doubting you, I know you guys have more experience at this than I do. I am just trying to understand what part the lifter plays when doing these tests.