Measuring for pushrods...part deux

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travis
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Re: Measuring for pushrods...part deux

Post by travis »

PBM rocker, 3/8” stud, 6.5 turns on the adjuster...7.700” PR...

371E8CD0-B43E-47E9-9DF2-104E3DFC3565.jpeg

Scorpion rocker, 7/16” stud, 5.5 turns down...required 7.936” PR...

D03113A8-5A34-462A-BBBA-1F46CD7DB80F.jpeg
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travis
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Re: Measuring for pushrods...part deux

Post by travis »

Neither rocker looks right doing it this way...the PBM is too short trunion to tip, while the scorpion is quite a bit too long. Both pics are on the base circle. Is this one of the “joys” of cheap heads???
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Re: Measuring for pushrods...part deux

Post by PRH »

The PBM looks reasonably close like that....... the body is just too short for the head.

The pushrod just looks way too long/rocker too high with the Scorpion.

As “back woods” as it sounds, with the Scorpion........ I’d “eyeball” the rocker position relative to the valve......to where I “liked” how it looked.
Then I’d check the net lift and sweep.

If I could get those 3 things to be “reasonable”...... I’d run it.

Shorten the pushrod .100 at a time from where it is now...... take a pic at each point until you’re at the point where it’s obviously too short.

We can vote on which one we like best 8)
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travis
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Re: Measuring for pushrods...part deux

Post by travis »

I will try that next.

In the meantime...E5AE head, crane conversion 3/8” studs, 6.5 turns on the adjuster, PBM rocker, 7.700” PR

F26FFADB-2224-439A-A20C-0F92AAB1CF22.jpeg
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Re: Measuring for pushrods...part deux

Post by PRH »

Looking at the pics from earlier, it looks like you were pretty close with the 7.600 PR and Scorpion rockers.

I’d have tried it with just a bit shorter PR, then checked the sweep and lift ......at full spring load.

On the stuff I’m usually working on, the ratio often loses .05+ going from checking springs to full load.
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Re: Measuring for pushrods...part deux

Post by PRH »

travis wrote: Sat Jan 18, 2020 4:27 pm I will try that next.

In the meantime...E5AE head, crane conversion 3/8” studs, 6.5 turns on the adjuster, PBM rocker, 7.700” PR


F26FFADB-2224-439A-A20C-0F92AAB1CF22.jpeg

It looks like the Scorpions would be too long on those heads.
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Re: Measuring for pushrods...part deux

Post by travis »

7.670” PR length with no preload gives a nice centered and fairly tight contact pattern on the valve tip, so I think a 7.700” PR will do the trick as I usually use 1/2 turn of preload. This is with the scorpions. It will either work or I’ll be putting guides in this thing in short order. In any case, I am done. Going 5.5 turns on the adjuster makes the PR way too long (wouldn’t stud length affect doing it this way???), so I did it the way that I am more comfortable with. I took so many pics I now don’t know which is which, but here is the contact pattern I ended up with at 7.670”.

64BA2C4D-E068-4B85-B866-AA04C41784CB.jpeg
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travis
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Re: Measuring for pushrods...part deux

Post by travis »

This is 9.5 turns on the adjuster, 7.670” PR. Creates .556” lift (not the most, but best tip pattern). This is on the base circle. Mid lift geometry is not perfect, but pretty good.

B7912D42-FB73-48B3-BF54-137EB627DF6D.jpeg
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Re: Measuring for pushrods...part deux

Post by PRH »

That would work for me.

With full spring load it won’t be .556 lift(ratio will be lower than the currently observed 1.63).
(wouldn’t stud length affect doing it this way???)
You saying that makes me think you’re still not following the instructions from the video correctly(for mid-lift geometry).
The stud could be a foot long...... would make no difference.

The starting point before counting the turns is to establish the top of the retainer is parallel to the “line”...... then count the turns from there.

You might have to turn the adjusting nut 1 turn .......or 50 turns(or anything in between)...... to get to that starting point....... depending on how long the stud is.
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Re: Measuring for pushrods...part deux

Post by travis »

I’m going to try it again (hopefully correctly this time)...like I need more numbers bouncing around in my head right now!

Many thanks to you and everyone else for their help on this. Once I get some spring shims and PR’s, the rest of this “should” fall into place
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Re: Measuring for pushrods...part deux

Post by PRH »

Regardless of what you come up with when you check it again, what you had with the 7.670 looked okay to me.
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Re: Measuring for pushrods...part deux

Post by travis »

Using the Straub method, possibly correctly this time, got me a PR length of 7.675” :lol: Add .025” of preload, and we are still looking at a 7.700” PR

Omg :lol:
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Re: Measuring for pushrods...part deux

Post by gmrocket »

travis wrote: Sat Jan 18, 2020 6:08 pm 7.670” PR length with no preload gives a nice centered and fairly tight contact pattern on the valve tip, so I think a 7.700” PR will do the trick as I usually use 1/2 turn of preload. This is with the scorpions. It will either work or I’ll be putting guides in this thing in short order. In any case, I am done. Going 5.5 turns on the adjuster makes the PR way too long (wouldn’t stud length affect doing it this way???), so I did it the way that I am more comfortable with. I took so many pics I now don’t know which is which, but here is the contact pattern I ended up with at 7.670”.


64BA2C4D-E068-4B85-B866-AA04C41784CB.jpeg
I vote you stop at this point :lol:

oh ya,,dont forget to check your ex too #-o
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Re: Measuring for pushrods...part deux

Post by Schurkey »

gmrocket wrote: Sat Jan 18, 2020 10:05 pmoh ya,,dont forget to check your ex too
When it's me, I look for narrowest sweep while staying reasonably centered. If I can't get that, I've got non-compatible parts or the valve tip heights are wrong.

I look at intake and exhaust on #1; and intake and exhaust on whatever the companion cylinder to #1 is. That's #6 for a 18436572 firing order. Using the companion cylinder means I don't have to dick with the degree wheel, I get a cylinder on both banks, and I get one front cylinder and one towards the rear.
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Re: Measuring for pushrods...part deux

Post by MadBill »

Aiming for the narrowest sweep is fine, but that always coincides with 90° at half lift and the angle measurement can be made far more accurately than the sweep check, especially if you lay a straightedge of the appropriate height* across the retainer and line it up with the center of the trunnion. *i.e., a height equal to the distance from the top of the retainer to the roller axis.
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