Having a little trouble getting the info I need to correctly order a set of hardened pushrods for my early 302. Have the Lunati pushrod checker assembly which gives me a length of 6.850" using zero lash as I am dealing with hydraulic rockers on a flat tappet cam. Now their instruction sheet has a chart for making length adjustments depending on the gross lift of your cam since their assembly gives the length for a cam with .708" net lift. Ok, my net lift gives me a correction factor of +.045" to add to the length making it 6.895 or 6.90'". Do I need to take into account anything else, as far as length, or am I good to go with the 6.90" pushrod?

 

Hi TBM,
The only other thing I can think of is the head gasket. The one used to take your readings should be close to the same thickness as the to-be-installed one.
I assume "hydraulic rockers" should read "hydraulic lifters".

 

I finally got it right after two nights, a sharpie pen and turning the engine over by hand. Not even close to the instructions with the Lunati checker. Helps to have the adjustable pushrod, an actual roller rocker and a sharpie to ink up valve stems. However, all the work and the cost of $150-$200 for pushrods makes the idea of roller rockers for a street engine very questionable. How much do you really gain versus the valve guide wear if you don't set the pushrod length correctly. Have read several instructions with rollers and most just say use new pushrods and that is it. No one got into the science of getting the exact right length to keep you centered over the valve stem. Next time there will be no next time...

 

Verbatum from the 1965/72 Ford passenger car parts catalog:

302

1968/69

"Before chg. / L4" C2OZ-6565-B .. Pushrod ~ 6.825"-long hydraulic tappets
------------------------------------------------------------------------

1969/

"after chg. / L4" C9OZ-6565-B .. Pushrod ~ 6.905"-long hydraulic tappets

D0OZ-6565-C .. Pushrod ~ 060" U.S.

D0OZ-6565-D .. Pushrod ~ 060" O.S.
-------------------------------------------------------------------------
68/70 C9OZ-6565-F .. Pushrod ~ mechanical tappets = 6.950" -long hardened steel

 

150 200 for push rods???


http://www.compcams.com/information/Products/Pushrods/

 

Yep, just look at the Summit Racing site. Comp Cams has 6.850" hardened pushrods for this application at $145.99. I can find 6.850" ($145), 6.875" ($102) and 6.900" ($86-115) hardened rods but as little as .05" can make a difference. Custom lengths actually at $144 so not maybe near the $200 mark after all. Stock lengths may not always work for getting a roller rocker in the correct position on the valve stem. Not an issue with standard rockers as their contact point is very large. Now whatever I have the length is between 6.850"-6.925". We'll see this weekend when I get my hand on a large micrometer.

 

The 6.825" stock length for this car will no longer work in this modified engine. Way too short and the roller way too high on the valve tip. As in my other answer the length will be between 6.800-6.925".

 

Hi TBM,
In your first post you suggest your pushrod length should be 6.895 or 6.90".
In your third post you say "whatever I have the length is between 6.850"-6.925", while in your previous post you wrote, "As in my other answer the length will be between 6.800-6.925".

The 2002 Ford Racing catalog lists part number M-6565-N332, pushrod, 0.312" diameter x 6.905" long (gage), "Production grade hardened and ground for use with guide plate." Suggested retail price $45 for set of 16.

They also sell a set that are 6.804" (gage), M-6565-L312, for the same price.

For measuring pushrod length, an 8" vernier caliper should be fine as this will be within one or two thousandths of an inch accuracy over its length. Don't forget that due to the through hole in the pushrod the measured length is somewhat shorter than the gage length, Ford says about .025".

 

Yes, in the first post I was using the rocker supplied by Lunati to get my pushrod length. Then after some web research I used an actual roller rocker and the adjustable Lunati pushrod to get my length after inking my valve stems. This, I feel, is more accurate than the first way. That meant there was no need for converting what I measured with the actual roller rocker versus a conversion needed with the mockup Lunati rocker. That is where the difference in lengths came about. The third post came from using that inking system of measurement and looking at the centration of the smudge mark on the valve stem top. That actually works really well just like in the articles I read.