MORE VALVE TRAIN QUESTIONS................

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CFD244

CFD244

"THE NEW OLDSMOBILES ARE IN EARLY THIS YEAR"
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Hi Folks

Getting ready to assemble the valve train. In picture #1 (hydraulic lifters with OEM 273 rocker assy), you see the push rod/adjuster relationship. This is with a brand new lifter on the base circle with .040 of preload measured between the plunger and the retaining clip (7/8 of a turn from 0). I suppose in a perfect world, a person would like to see a little more space between the rocker tip and the push rod cup. But these are brand new push rods, and I have them. Am I asking for trouble running them like this?

Just for ***** and giggles, I installed the OEM non adjustable rocker assy (thinking about going with this set up)on the original push rods and got a whopping .125 + preload. As you can see in the next 2 pics, the rocker shaft is riding above the pedestals at 0 preload. The lifter pic is actually the preload. What gives? How did this thing even run with that much preload??

Thanks FABO

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You should have about 1.5 threads out of the adjusters. If not, your pushrod cups may contact the rockers. 65'
 
I would use shorter pushrods. You need a pushrod checker. Get the adjusters two threads out. adjust the checker for zero lash. Remove it. Measure it, then add .050 to that figure and order pushrods that length.
 
I am not sure what we are looking at in the pic with the factory hyd
rockers. I see gaps between the shaft & pedestals.....
 
Heads milled? Deck milled? Cam base circle? I've forgotten "which direction", but I know hydro and solid pushrods are different length
 
Adjustable pushrod I have is ball/ball.
I tried googling "measuring preload" and went down a rabbit hole lol, I've never done it before.
As mentioned above "by looks" with adj rocker, the adjuster isnt turned in enough. I have some stock ball/cup pushrods if you need a measurement.
 
Bewy said:
I am not sure what we are looking at in the pic with the factory hyd
rockers. I see gaps between the shaft & pedestals.....
Click to expand...
The last pic just shows the .125 preload on the lifter with the OEM non adjustable rocker assembly. Pic 2 shows how much more the OEM non adjustable rocker shafts would have to be tightened down from zero preload on the lifter.
 
4spdragtop said:
Adjustable pushrod I have is ball/ball.
I tried googling "measuring preload" and went down a rabbit hole lol, I've never done it before.
As mentioned above "by looks" with adj rocker, the adjuster isnt turned in enough. I have some stock ball/cup pushrods if you need a measurement.
Click to expand...
It's weird. The ball and cup's in the pic are actually new Comp Cams 7692's. I have a set of OEM ball and cup that came with a set of 273 rockers I bought. They are actually longer.
 
Maybe I'll mill the underside of the rocker to expose more threads, and grind the valve tips to open it up.
 
4spdragtop said:
What's Comp specs for preload?
Click to expand...
Comp says .030 =/- .010. I'm shooting for .040.

I can get everything adjusted to that, but there isn't enough thread showing on the adjuster........I need shorter pushrods. But, you know what kind of a PITA it is getting things north of the 49th. I was hoping my clearance was adequate to run the rods I have.

Now, with the OEM non adjustables, I figured that they would be bolt on and go..........Not the case. With OEM rods and rockers I am getting .125 preload which appears insane.
 
CFD244 said:
Maybe I'll mill the underside of the rocker to expose more threads, and grind the valve tips to open it up.
Click to expand...

Are you crazy? Measure the pushrod length, you can get one anywhere. Shim the shafts .060 for the hydraulic rockers and be done.
 
Were the heads shaved? Judging by pics the oem hydraulics look way off?
CFD244 said:
Comp says .030 =/- .010. I'm shooting for .040.

I can get everything adjusted to that, but there isn't enough thread showing on the adjuster........I need shorter pushrods. But, you know what kind of a PITA it is getting things north of the 49th. I was hoping my clearance was adequate to run the rods I have.

Now, with the OEM non adjustables, I figured that they would be bolt on and go..........Not the case. With OEM rods and rockers I am getting .125 preload which appears insane.
Click to expand...
 
If you're wondering where all the clearance went, by using factory mechanical components and a hydraulic lifer, they'll be an installed height discrepancy. Cup socket on the mechanical lifter will be about 1.63 inch. and about 1.79 inch for the hydraulic lifter. You just lost 160 thou of room. You need shorter push rods.
 
4spdragtop said:
Were the heads shaved? Judging by pics the oem hydraulics look way off?
Click to expand...
The deck was cleaned up, and the head surface was cleaned up as well. Just enough.........When I drop my intake on with the gaskets in place, the bolt holes line up just fine. I assume if so much was removed as to mess up the push rod length, that intake would be way off as well.
 
you now know the problem, hydraulic lifters are longer than solid's. so you NEED shorter pushrods.
so to answer your question, yes you're asking for trouble like that.
 
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