Hi All,

I am getting ready to buy new pushrods for my 390 build. I have an edelbrock 2106 with lifters and springs installed. I want to make sure that I am going to buy the right size pushrods and avoid issues like bending or even lifter or valve damage.

I put together a spreadsheet that shows the measurement I got with the Comp Cams pushrod size tool. Also on the spreadsheet I calculated the lifter preload that i would get by subtracting the checker tool measurement from the new pushrod sizes (2 different options).

The heads have been serviced, resurfaced and a couple of new valve seats had to be installed. It has been suggested that I take another set of the rocker arm oil baffles and cut the wavy part out and use them as a shim to raise the rocker assembly approximately .040. Is this a good idea? The preload amounts look pretty high to me.

Can anyone point me in the right direction? Thanks!


Here is my spreadsheet:

 

Anyone out there?

 

Why if your compensating with the push rods? That now would give you two intangibles instead of one.

 

True...Thanks. I guess my real question is if you look at the spreadsheet you can see the preload that I would get using either one of the new pushrod sizes, how much preload is too much for this engine and will I have to get different size pushrods to compensate or is it ok for them to be "close enough"?

 

Also, would adjustable pushrods from Crower be a good option in this case?

 

Myself, I'd go with adjustable rockers. A little more expensive but in my op. fool proof.

 

Ford service recommended procedure from the 1960 manual is;


Use the service tool to bleed down the lifter when at the base of the lobe and measure the valve gap at the valve stem, clearance needs to be .040-.060 cold.


Now with new lifters it is easy to compress the lifter down and measure. I also use the Comp Cam pushrod sizing tool to set the length and when the clearance is correct (I use .050) remove the tool and measure the length.


Jeff

 

Hi Jeff,

Thanks for your input. If i am not mistaken the tool that ford mentions in the manual has long since been obsolete. Are you saying that you are basically doing the same thing with the comp cams pushrod checker tool?

Are you inserting a .050 feeler guage between the rocker tip and the valve stem then using the pushrod too to measure the length? Won't that leave play in the rocker once the feeler guage is removed? Maybe i am not understanding. Thanks!

 

You have to collapsed the lifter at base lobe and hold it there. The Ford tool was a lever that did that for you (Similar to the tools for changing valve seals on assembled engines, but in reverse).
You then check the clearance at the tip. Subtract the .0.40-.060 recommended clearance from the measured clearance and add that figure to the installed pushrod to get the length of the required pushrod. Worked for Ford throughout the lifecycle of the FE.


With the pushrod tool on newly assembled FE it takes less pressure to collapse the lifter (never pre-pump up FE lifters). With the pushrod checker adjust the length, bottom out the lifter with a pry bar and check the clearance at the tip. Repeat adjusting the pushrod tool until correct clearance has been met. Remove the rocker shaft and measure the length of the tool to get the proper length pushrod. This is a direct reading, no need to use the chart. Disregard the chart in the beginning of this thread. There is NO PRELOAD, oil pressure adjusts the lash.


The lifter is collapsed so once the engine is started, oil pressure pumps up the lifter but you still have .040-.060 of adjustment inside the lifter for expansion so no bent pushrods. Actually less depending upon the rocker ratio.

Same principle with adjustable rocker arms but you tighten down the nut from zero lash plus the correct number of turns. 1 turn = .050 on fine threads.


Jeff

 

Hi Jeff,

Thanks for the info! I just looked up the valve adjustment online and i found a picture of what you are saying from the old ford shop manual....makes sense now! Question: If you are allowing for .050 clearance at the valve stem tip wouldn't it be the same thing I adjusted the pushrod checker to zero lash, remove rocker assembly and then measure the checker length and then just add .050 to get the total length needed? Thanks!

 

Depending upon what brand of checker tool you use. Some compensate for hollow pushrods since they do not have complete spherical ends. Also you do have to consider the rocker arm ratio, none are a 1:1 ratio. You do not want to order custom pushrods more than once when some cost $3 to $7 each.



Jeff