Pushrods for guideplates

Yes, the stock 63-66 (before change level 11) pushrods should work just fine. They were hardened, because they relied on integral pushrod guide slots in the head. After CL 11, the 289 2V and 289 4V used "rail" rockers, with guides on the tip keeping the tip aligned. The 289HP continued to use the earlier hardened pushrods until it was discontinued. CL 11 included a valve change, with the tip extended higher to keep the rails from contacting the retainer rails. Do not mix the before/after CL 11 style valves and rockers.

You want to measure to determine the correct length pushrods. Every engine is different and especially with roller rockers and aftermarket camshafts it's important to get the geometry right. The consequence of incorrect geometry is rapid valve guide wear. Buy an adjustable length pushrod, mark the valve tip with machinists blue die or a magic marker, then rotate the engine over and look at the mark. There are many articles on the internet that go into detail on how to do it.

Hack said:

You want to measure to determine the correct length pushrods. Every engine is different and especially with roller rockers and aftermarket camshafts it's important to get the geometry right. The consequence of incorrect geometry is rapid valve guide wear. Buy an adjustable length pushrod, mark the valve tip with machinists blue die or a magic marker, then rotate the engine over and look at the mark. There are many articles on the internet that go into detail on how to do it.

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make sure you use a solid lifter when doing so.

or, checking springs.....

You can fashion a solid lifter with the old ones, I just took them apart and filled with JB Weld, had a solid lifter in a couple hours.

AZmustang98 said:

So, I will need to purchase an adjustable pushrod, and get a hold of a solid lifter to check the right geometry? I am in no hurry in getting it together so Ill check around...

@ PoppyMod, what do you mean by checking springs?

Thanks

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Hi,
Kits are sold (CompCam, being one, Summit, JEGs etc) by the big box houses that contain 2 very light valve springs and an adjustable push rod (PR). These springs allow one to simply replace the standard valve springs (no need to remove head) and start the check. For those of us running hydraulic lifters, these springs are light enough, so as, not depress the hyd. plunger when cycling through the valve motion for the check. Of course, if you are in the throngs of engine assembly, there is not the same need for the springs as you can fashion a solid lifter, but, you still need the adjustable PR. Be aware, Any change in height between the test lifter and the actual unit being installed will, obviously, nullify your results. This is why I advocate the springs, especially for those new to the process. The kit cost about $20, if I recall.
Hope this clears up any questions. Good Luck with your project.

what is the stock length of a 69 302 pushrod?

mustangmike6996 said:

what is the stock length of a 69 302 pushrod?

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Interesting question? As, it depends on how one measures. There are various tools used just ask a cam mfg.
Why would you ask?

i am going to order the adj pushrod checker. i just need to know the stock length so i can figure out which range i need.

mustangmike6996 said:

i am going to order the adj pushrod checker. i just need to know the stock length so i can figure out which range i need.

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OK. Talk to the tech guy of the vendor your calling. They'll have an idea.

PoppyMod,
Please realize that the following is not an attempt to refute and/or take exception with your comments/advice, just an attempt to gain a more clear understanding of the subject.

I am in total agreement with the use of a solid lifter and checking spring for checking certain valve train issues, such as piston to valve clearance, etc. What I'm having a hard time wrapping my brain around is why to use them for checking pushrod length? It would seem that if your cam/hydraulic lifter setup specifies, for example, a .060" pre-load/compression of the lifter, you would be eliminating that preload by using a light, checking spring or solid lifter, or both, thereby giving a false reading of the required pushrod length by .060"-ish? It seems that would show the need for a pushrod that was .060" too short. Am I missing something?
Thanks,
Gene

horseballz said:

PoppyMod,
Please realize that the following is not an attempt to refute and/or take exception with your comments/advice, just an attempt to gain a more clear understanding of the subject.

I am in total agreement with the use of a solid lifter and checking spring for checking certain valve train issues, such as piston to valve clearance, etc. What I'm having a hard time wrapping my brain around is why to use them for checking pushrod length? It would seem that if your cam/hydraulic lifter setup specifies, for example, a .060" pre-load/compression of the lifter, you would be eliminating that preload by using a light, checking spring or solid lifter, or both, thereby giving a false reading of the required pushrod length by .060"-ish? It seems that would show the need for a pushrod that was .060" too short. Am I missing something?
Thanks,
Gene

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Hi Gene,
None taken. Some of this may be redundant, but, I want to paint a full picture.
I'll start with, in building/assembling my own engines, I have followed the rule for adjusting the pre-load of hydraulic lifters to be within a range of .020 to .060". There may be exceptions, but, for spirited street engines, this has worked well and have never lost one.
OK. The idea of proper P/R geo (geometry), when set correctly, is to insure as near a 90 deg. relationship between the valve tip and it's rocker point of contact, as possible, when cycled. A correct length is described as the distance between the rocker point of contact with the P/R and it's point of contact with the lifter (no depression of the plunger) in the case of hydraulic. The use of checking springs substituted for the valve springs, are just heavy enough to keep the valves closed, yet, when cycled are light enough as to not depress the lifter plunger, thus distorting the length.
So, let's say we have the checking springs in place, we've installed an adjustable P/R and it's set 6.50" and we have marked the tip of the valve in some way. We cycle the valves a few times. We note the wear pattern is short, that is, it's wear pattern is toward the intake. we remove the P/R and unscrew the tip (making it longer). After several iterations we have a perfect center mark and have determined the P/R should be 6.75". At this point after testing and retesting we're satisfied the wear mark is dead center and about .070, or so wide. This is good.
Now getting back to my suggestive pre-load of .020-.060. How do we get there? I'll use this as an example as these are the rocker studs I run. Having 7/16 X 20 rocker studs, one can determine that one complete rotation (360 degs.) of the nut will travel downward .050". this, based on the fact, you have 20 threads/inch. Dividing 1/20=.050". Now, to add to the formula, you have your rocker ratio as the rocker is not 100% linear at it's axis, is it? It's curved. So, If I were to screw down my adjustment nut 1 full turn thinking my pre-load is good at .050. After all it is between .020-.060....I'd be wrong! Why? because, I'm running a 1.6 ratio rocker, the ".6" has to be considered. Therefore, my ooops! of .050, in reality becomes ".080", by virtue of .050 X 1.6 = .080. now too much pre-load. Too much pre-load can cause reduced engine vacuum.
Simply stated, you use the springs to get an accurate P/R length with which to begin the check. The check being, a centered wear mark with a narrow track and an "ideal" (90 deg) relationship. Thus, within reason, you are getting 100% of the cam lobe's ability to transfer it's total "lift" characteristics. If the push rod is too long coil bind, valves touching can make for a bad day.
I hope this is not too much stuff to take absorb. I hope I answered why it is important to start with a correct base P/R length.
Happy Motoring!

PoppyMod,
Not too much to digest.
"I hope this is not too much stuff to take absorb. I hope I answered why it is important to start with a correct base P/R length."
When I set my pre-load, I use a dial indicator on the pushrod end of the rocker arm to eliminate the need to factor in the rocker arm ratio. My confusion still lies with the thinking that if you set your "ideal" (90 deg) relationship and perfectly center the proper width wear mark on the valve and then pre-load the lifter, whatever amount, we will move the wear pattern slightly toward the exhaust side of the valve. It has always been my understanding that if the wear pattern is going to not end up perfectly centered, it should err, ever so slightly, toward the intake side? Please correct me, if necessary, as I want a good understanding as I learn. I have read, in several places, that after all other measurement are taken, it is a good idea to make a final check with all parts to be used installed and properly pre-loaded to confirm that the wear pattern is dead centered or, if slightly off, to be justified to the intake side.
Thanks for sharing your knowledge and experience,
Gene

H,
Yes, error bias on the short side would be preferred. The final check is, after several cycles (hours of operation) pulling a V/C will give a good indication of where the wear is taking place. I think you have it. I just think using checking springs allow's one to not have to pull a head or during assembly not torque/re-torque the gaskets etc.
Happy Motoring Gene!

PoppyMod,
Thanks again for sharing and helping us all to have a clear and complete picture.
Enjoy Your Better Idea,
Gene