Rockers too high on the studs?

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travis
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Re: Rockers too high on the studs?

Post by travis »

I probably didn't describe that well (sleep deprived here too). 7.750" with the plunger fully depressed. On a 3/8"-24 stud, 1 turn of the adjuster should equal approx .042"...so to fully depress the plunger was 2 1/4 turns, thus 2.25x.042" equals .0945". So my thinking here is that with about 1 turn of lifter preload (I actually don't run mine that tight), .0945"-.042"=0.0525", so I would need about a .050 to .070" shorter pushrod to make everything right.

Or...I may be WAY off base here :lol:

Realistically, I shouldn't be working on this thing at all right now...too many distractions and a major shake up at home, but that is a story for another time...so no reason for you or anybody to feel bad. I know better...my head just hasn't been in the game and I keep finding myself making stupid mistakes with everything lately.
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Re: Rockers too high on the studs?

Post by gmrocket »

travis wrote: Thu Jan 02, 2020 2:33 am One BIG brain fart I did when checking with the PBM rockers was not accounting for the lifter plunger collapsing (too many distractions), so any previous numbers was basically garbage...

With the Scorpion rockers in place, using the Straub method mentioned earlier in this post, at .272" valve lift (1/2 max lift), I get a length of 7.750" when testing in .050" increments. But...there is also the lifter plunger bottomed out which is 2 1/4 turns down from 0 lash, which on a 3/8" stud calculates to .0945". So...7.700" should be about right, correct?
The best way to see exactly how your rocker is contacting the tip with a hydraulic lifter as it goes through the sweep/lift range is to pull the guts out of one lifter and pack it with washers to get the plunger where it will be at running condition.

Get rid of your checking spring and install a stock soft spring ... this will put some poundage on your whole rocker set up. My mantin p rod checkers handle the pressure just fine
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Re: Rockers too high on the studs?

Post by gmrocket »

MadBill wrote: Wed Jan 01, 2020 10:32 pm
gmrocket wrote: Wed Jan 01, 2020 4:45 pm..
Yep, the thought that the wheel rotates back and forth as it travels up and down , does not happen.

For one, at upper upper rpm's. There isn't enough time to rotate back and forth, if you have that happening, you have major friction between tip and wheel . It skids on the return to seat journey, and will rotate/skid on the opening
As with solid roller lifters discussions, the rationale re spin/skid ratios for roller tip rockers is compelling, but AFAIK, data is lacking. With all the high speed photography and strobe videos on the net, surely someone has posted one showing roller tip action in sufficient detail to make or break the case? :-k
The roller wheel on a lifter could only skid or turn in one direction, so not the same discussion really since the wheel on the rocker swipes the tip in one direction during opening and the other during closing

The lifter wheel accelerates or decelerates and skids only in the one direction
Last edited by gmrocket on Thu Jan 02, 2020 6:06 am, edited 1 time in total.
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Re: Rockers too high on the studs?

Post by gmrocket »

Kevin Johnson wrote: Thu Jan 02, 2020 12:56 am
MadBill wrote: Wed Jan 01, 2020 10:32 pm
gmrocket wrote: Wed Jan 01, 2020 4:45 pm..
Yep, the thought that the wheel rotates back and forth as it travels up and down , does not happen.

For one, at upper upper rpm's. There isn't enough time to rotate back and forth, if you have that happening, you have major friction between tip and wheel . It skids on the return to seat journey, and will rotate/skid on the opening
As with solid roller lifters discussions, the rationale re spin/skid ratios for roller tip rockers is compelling, but AFAIK, data is lacking. With all the high speed photography and strobe videos on the net, surely someone has posted one showing roller tip action in sufficient detail to make or break the case? :-k


You can see the wheel rotate.
That's it..you can clearly see it rotating in the one direction it would during opening, sweeping across the top .
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Re: Rockers too high on the studs?

Post by travis »

gmrocket wrote: Thu Jan 02, 2020 5:39 am
The best way to see exactly how your rocker is contacting the tip with a hydraulic lifter as it goes through the sweep/lift range is to pull the guts out of one lifter and pack it with washers to get the plunger where it will be at running condition.

I agree with this, except I can't figure out how to get the plunger out of these. How do you get the plunger out past the part that holds the link bar to the lifter body?
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Re: Rockers too high on the studs?

Post by 77cruiser »

travis wrote: Thu Jan 02, 2020 6:57 am
gmrocket wrote: Thu Jan 02, 2020 5:39 am
The best way to see exactly how your rocker is contacting the tip with a hydraulic lifter as it goes through the sweep/lift range is to pull the guts out of one lifter and pack it with washers to get the plunger where it will be at running condition.

I agree with this, except I can't figure out how to get the plunger out of these. How do you get the plunger out past the part that holds the link bar to the lifter body?
You can't. Get a single non link lifter & use that shimmed to the height you need.
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Re: Rockers too high on the studs?

Post by BigBlocksOnTop2 »

I had an issue with Canfield heads and Scorpion rockers. The issue was the push rods were touching the rockers. I had to relieve a small area there. Your push rod looks real close to the trunion. The pic made me think of the issue I had.
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Re: Rockers too high on the studs?

Post by gmrocket »

travis wrote: Thu Jan 02, 2020 6:57 am
gmrocket wrote: Thu Jan 02, 2020 5:39 am
The best way to see exactly how your rocker is contacting the tip with a hydraulic lifter as it goes through the sweep/lift range is to pull the guts out of one lifter and pack it with washers to get the plunger where it will be at running condition.

I agree with this, except I can't figure out how to get the plunger out of these. How do you get the plunger out past the part that holds the link bar to the lifter body?
If it bottoms out that easily, just subtract the distance it compresses from the p Rod length
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Re: Rockers too high on the studs?

Post by FC-Pilot »

travis wrote: Thu Jan 02, 2020 4:25 am I probably didn't describe that well (sleep deprived here too). 7.750" with the plunger fully depressed. On a 3/8"-24 stud, 1 turn of the adjuster should equal approx .042"...so to fully depress the plunger was 2 1/4 turns, thus 2.25x.042" equals .0945". So my thinking here is that with about 1 turn of lifter preload (I actually don't run mine that tight), .0945"-.042"=0.0525", so I would need about a .050 to .070" shorter pushrod to make everything right.

Or...I may be WAY off base here :lol:

Realistically, I shouldn't be working on this thing at all right now...too many distractions and a major shake up at home, but that is a story for another time...so no reason for you or anybody to feel bad. I know better...my head just hasn't been in the game and I keep finding myself making stupid mistakes with everything lately.
Holy cow, my head really was scrambled. 😝 Yes, the lifter would not have near an inch of plunger movement. I need to get my head checked. 😂

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Re: Rockers too high on the studs?

Post by MadBill »

Surely it would take a while (if ever) under load for a soft checking spring to cause any measurable leakdown of a fully oil-filled hydraulic? Plus you could check for same just by backing off the rocker and seeing if force on the pushrod can depress the button at all.
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Re: Rockers too high on the studs?

Post by lt4orbust »

since your on the subject , is rocker geometry used the same for ford chevy and chry push rod engines ? ie should the geometry be close or at 90 degrees for both valve side and push rod side at mid lift ?
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