Pushrod conundrum

So I have a question on pushrod length. I'm not so sure that my lack of vacuum isn't due to my adjustable valve train. My adjusters are basically backed out all the way and I'm wondering if this isn't the reason my vac readings are so low and why my garage floor has a thick layer of soot.

I have shaft mounted 1.65 rockers. A C9 head that hase been milled 0.070", and a NOS head gasket with a 0.035" crush thickness.

I don't have a good way to accurately measure the length of the rods that I have. I got them from Will in between CI to VI transition. With a tape measure (what I had) they look to be 8 1/8" long tip to tip. I realize this isn't a proper measurement of a ball/cup rod, but I do with what I have.

I used an adjustable pushrod with the adjuster roughly centered and wound up with something that measured 8 1/16". Matt is on vacation till the 10th, so I've got time to order, but he has the 8.030" ball/cup pushrods.

My question is, given the above information, does my measurement of 8 1/16" make sense? In the meantime, I'll try to find a more better way to measure than with some clunky tape...

would the calipers shaped like a "U" help? (called 'outside' rather than the 'inside' ones).
push the leg of 1 side into the cup, slide the other under the ball, adjust/tighten;
slide ball side off ball, place on measuring instrument.
Big box auto prts has 4 loan?
Keep talkin!

BTW: I don't know the standard for how to measure adjustable P/Rs
but when a machinest, this wuz onea our tools.

Howdy Bob:

When adjusting with the engine warmed up and just turned off, are you able to spin or twist the pushrods with the rocker in the up, or open position? If not, can you loosen the adjuster on the rocker to where you can spin the pushrods with the rocker arm in the up or closed valve position? If so, you don't have a valve hanging open. I'm guessing that is what you are thinking.

If that isn't it then you will likely be looking for a shorter pushrod.

Adios, David

Steve, i believe you need pushrods closer to 7.950". Put your adjustable pushrod in there & choose the length where the tip of the rocker has the less sweep close to the center of the valve stem.Then you measure with either a solid lifter or install a light spring so the hydraulic lifter is not in a collapsed position & the adjuster is in its mid adjustment.
Clay Smith cams can make you the correct length pushrod from your measurements. Bill

I reckon if I'm going to do this, I should do it right. Where do i hey a solid lifter? Only need 1 and not a whole set.

cr_bobcat":1k7ukjle said:

I reckon if I'm going to do this, I should do it right. Where do i hey a solid lifter? Only need 1 and not a whole set.

Click to expand...

me 2, goin ta NAPA Mon.
Only oneada 3 local stores will sell me 1 (know them from buyin so many bronk prts there). They R gonna drive to the other store to get it & deliver it back to their own store / onto the garage I'm @. Not unusual for these places (or out from a "hub" to local or garage).
Try it you'll like it.

Good call Chad! The Advanced Auto around the corner from my office had one in stock (according to the interwebs). Paid for and I should have it when I run out for lunch tomorrow. $4 well spent!

hope that's the right advice, R adj P/R measured that way?
Enjoy~

You are going to have to pull the head to do this....Be careful the lifters may or may not be the same height...I would try something else.

Shoot. You're right. I keep forgetting that i can't pull lifters without removing the head on these engines. I'll have to think about this some more. Hmmmm....think of got start of an idea. I'll sleep on it and see where this train of thought leads me...

No problem, remove the distributor & prime the oil pump with a drill on the hex oil pump shaft, that will pump up the lifter.
The other method is remove the rocker shaft & get a generic 2# spring from your local hardware store & remove the regular spring by putting air in the cylinder @ install the light weight till you get the right length.
Find another lifter & measure the distance between a fully collapsed lifter to one that is not collapsed & subtract that measurement to get the correct length needed. I would guess a lifter plunger travel is close to 1/8" ??
Best of luck.

Boy your thread sounds familiar!! I bought adjustable rockers and went with a new set of pushrods the same length. Once installed they were way too long and the adjusters were only engaged into the rocker by two or three threads. I measured up what I needed and RAU made me a set. They were perfect. Then I found out that adjusting lash by feel can be a very subjective thing. Never got it where I felt good about what I was hearing. I called Hylift Johnson who made my lifters and got the recommended compression tolerance spec. from them. Then I measured one adjuster thread and did the math. I adjusted them to the middle of the tolerance. Didn't try to turn the rods just took out the end freeplay and tightened from there. Worked perfect!!! BYT the way I also pulled a lifter out of the bore and had to tear it apart! glad it worked out for you!!

Well, I replaced the 8.125" pushrods with some 8.010" rods. This looks MUCH better! I have a small tick so I have some adjustment to do but I'm liking what I see. Prior to the change I had something around 13-14" of vac and now I'm at 14-15 and I think it will come up slightly still yet as I haven't let it idle long enough yet to get to temp. Another hour or so of fiddling around ought to get me there!

Congrats on the good progress it wont be long until its a great driver!