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Understanding 1.4 slipper foot rocker geo. Not elephant foot.
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Onceler
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PostPosted: Mon Dec 30, 2019 11:37 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

67rustavenger wrote:
Onceler wrote:
Sorry to hijack, but I didn’t won’t to start another thread.

You're not hijacking the thread. You're adding to the knowledge and understanding of the proper setup of 1.4:1 rocker setup.

This is a collaborative thread.
Everyone's input is a new level of understanding.

As far as I can see in the last image. You are still over the top of the center of the valve tip.

As asked before. "Did you shave the rocker shaft blocks?"
It makes a difference!

Thanks, 67rustavenger, no I didn’t shave the blocks. Once the shutdown is over at work, I’ll shave them down 0.100” and post a pic. Thank you all for the help, I just don’t have the eye, but prefer not to wear out my heads.
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rodeking
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PostPosted: Tue Dec 31, 2019 7:09 am    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

Stop trying to "eyeball" it. Locate the center of the bolt. Measure the distance from the top of the retainer to the top of the stem or lash cap. Scribe a line on the scale that same distance up from the bottom as shown in the pic. Lay the scale on the retainer and measure the distance from the bolt center to the scribed line. Shave the blocks or add shims equal to that distance. Done.
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PostPosted: Tue Dec 31, 2019 8:41 am    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

WTF?? what does the retainer high have to do with anything?? and no the pushrod angle has squat to do with the geo. Im not sure what scats full oiling is but..I would have the adjuster up in the rocker as far as they go and then 1/4 to 1/2 turn out.if the oil holes dont line up good then fix that issue like a slot in the top or bottom thread at the oil hole so it does. your hight looks good,possiably remove the 1 shim. hard to tell. but you many not need to shave the rocker blocks, and certainly not .100". be sure to deburr the oil hole edges in the cup and add flats to the pushrod wnds and deburr the holes their too.
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rodeking
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PostPosted: Tue Dec 31, 2019 8:45 am    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

read it
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rugblaster
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PostPosted: Wed Jan 01, 2020 1:08 am    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

It's 2 am here, new years and I'm pretty drunked up, but I think what he is describing concerning the retainer is at half lift there should be a 90 degree angle from the center of the rocker shaft (and by default the rocker itself) and the center line of the valve (and by default the retainer) unless something is really bent.

You have to take account of how far the valve stem/lash cap is above the retainer.

The op's last photo looks to be more than 90 degrees to me ......maybe 110 or so....hard to say. Taking material off the rocker blocks will tighten the angle.
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Last edited by rugblaster on Wed Jan 01, 2020 5:10 pm; edited 2 times in total
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Onceler
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PostPosted: Wed Jan 01, 2020 1:19 am    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

rugblaster wrote:
It's 2 am here, new years and I'm pretty drunked up, but I think what he is describing concerning the retainer is at half lift there should be a 90 degree angle from the center of the rocker shaft (and by default the rocker itself) and the center line of the valve (and by default the retainer) unless something is really bent.

3am here and I’m pretty lit too, but is that at half lift, or 0 lift? If half lift I’ll need to shave the blocks down ~0.120” but if at 0 lift I need to install .030” shims.
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PostPosted: Wed Jan 01, 2020 1:28 am    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

the 90 degree angle your looking for is at half lift.....go back and read how I described to do this and read it carefully. Middle of the third page.
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PostPosted: Wed Jan 01, 2020 10:24 am    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

The scribed line represents the top of the lash cap and is at 90 deg to the stem axis. You want that line to go through the center of the rocker shaft at whatever lift you choose to set up for. This method eliminates trying to eyeball the line from the stem/cap top thru the shaft center.

Whether you choose to do that at 1/3, 1/2 or 2/3 could be the subject of a doctoral dissertation.

Setting at 1/2 lift will give the absolute minimum swipe width but doesn't consider spring force or ramp acceleration.

The greatest ramp acceleration (and rocker accel in relation to stem) occurs at low lift so engines that see a lot of high rpm operation may be better off setting at 1/4 or 1/3 lift. High rpm means more valve inertia to offset the higher spring force at higher lift.

Low rpms means low valve inertia so the greatest scrub force occurs at higher lift when there is higher spring force pushing the stem into the rocker and there is still some ramp acceleration. There is zero ramp acceleration on the nose where spring force is the highest so the scrub force at that point is zero. So somewhere around 2/3 to 3/4 lift is where the greatest scrub force happens depending on the lobe profile.

Theoretically, from a max performance consideration, there is some benefit to setting at low lift when vac is increasing the fastest due to piston acceleration but probably not enough to consider except for all out race.

So take your pick where you set it up. Half lift is generally considered a good compromise for a street engine.

Happy New Year Very Happy
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PostPosted: Wed Jan 01, 2020 1:13 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

rodeking wrote:
The scribed line represents the top of the lash cap and is at 90 deg to the stem axis. You want that line to go through the center of the rocker shaft at whatever lift you choose to set up for. This method eliminates trying to eyeball the line from the stem/cap top thru the shaft center.

Whether you choose to do that at 1/3, 1/2 or 2/3 could be the subject of a doctoral dissertation.

Setting at 1/2 lift will give the absolute minimum swipe width but doesn't consider spring force or ramp acceleration.

The greatest ramp acceleration (and rocker accel in relation to stem) occurs at low lift so engines that see a lot of high rpm operation may be better off setting at 1/4 or 1/3 lift. High rpm means more valve inertia to offset the higher spring force at higher lift.

Low rpms means low valve inertia so the greatest scrub force occurs at higher lift when there is higher spring force pushing the stem into the rocker and there is still some ramp acceleration. There is zero ramp acceleration on the nose where spring force is the highest so the scrub force at that point is zero. So somewhere around 2/3 to 3/4 lift is where the greatest scrub force happens depending on the lobe profile.

Theoretically, from a max performance consideration, there is some benefit to setting at low lift when vac is increasing the fastest due to piston acceleration but probably not enough to consider except for all out race.

So take your pick where you set it up. Half lift is generally considered a good compromise for a street engine.

Happy New Year Very Happy


Excellent write-up! I never considered altering swipe based on rpm and ramp profile.
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PostPosted: Wed Jan 01, 2020 3:10 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

rodeking wrote:
The scribed line represents the top of the lash cap and is at 90 deg to the stem axis. You want that line to go through the center of the rocker shaft at whatever lift you choose to set up for. This method eliminates trying to eyeball the line from the stem/cap top thru the shaft center.

Whether you choose to do that at 1/3, 1/2 or 2/3 could be the subject of a doctoral dissertation.

Setting at 1/2 lift will give the absolute minimum swipe width but doesn't consider spring force or ramp acceleration.

The greatest ramp acceleration (and rocker accel in relation to stem) occurs at low lift so engines that see a lot of high rpm operation may be better off setting at 1/4 or 1/3 lift. High rpm means more valve inertia to offset the higher spring force at higher lift.

Low rpms means low valve inertia so the greatest scrub force occurs at higher lift when there is higher spring force pushing the stem into the rocker and there is still some ramp acceleration. There is zero ramp acceleration on the nose where spring force is the highest so the scrub force at that point is zero. So somewhere around 2/3 to 3/4 lift is where the greatest scrub force happens depending on the lobe profile.

Theoretically, from a max performance consideration, there is some benefit to setting at low lift when vac is increasing the fastest due to piston acceleration but probably not enough to consider except for all out race.

So take your pick where you set it up. Half lift is generally considered a good compromise for a street engine.

Happy New Year Very Happy


Holy crap! This one post along with the “rodeking method” should be a sticky.
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Onceler
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PostPosted: Wed Jan 01, 2020 7:47 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

So I managed to make the tools as best I could atm. Then I chose 1/2 lift from rodeking’s post.
Image may have been reduced in size. Click image to view fullscreen.
set the jig on the rocker
Image may have been reduced in size. Click image to view fullscreen.
and measured
Image may have been reduced in size. Click image to view fullscreen.
Looks like I need to shave the blocks down 4mm (0.157”)
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PostPosted: Wed Jan 01, 2020 9:09 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

Is that a mock-up spring?

Also, I keep reading people mentioning to lower the blocks for certain situations. Just wanted to point out that if you lower the blocks instead of the mounting pads on the head, the likelihood that your rockers will rub on the pads is very high. If you shorten the blocks, check that all your rockers still clear the mounting pads.
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PostPosted: Wed Jan 01, 2020 9:33 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

Ah, good point. It does look like my rockers will hit the mounting pads if I shave the blocks down. Now it looks like there is no way to remove that much material from the blocks. I’ll have to remove the studs and use the mill at work to shave down the pads. (The mill at work is kinda wonky, wish me luck)
Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Also, yes those are my mock-up springs, I have Dan Ruddock’s beehives I’m gonna run.
But I’m sold on the rodeking method, seems pure genius
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PostPosted: Thu Jan 02, 2020 6:54 am    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

Onceler wrote:
So I managed to make the tools as best I could atm. Then I chose 1/2 lift from rodeking’s post.
Image may have been reduced in size. Click image to view fullscreen.
set the jig on the rocker
Image may have been reduced in size. Click image to view fullscreen.
and measured
Image may have been reduced in size. Click image to view fullscreen.
Looks like I need to shave the blocks down 4mm (0.157”)



Looking at your pushrod to adjuster alignment it looks like a taller lash cap would help straighten this alignment better and would also negate the need to shave the blocks by such amount. Just another thing to consider.
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PostPosted: Thu May 20, 2021 4:24 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

VOLTWAGEN wrote:
67rustavenger wrote:
rugblaster wrote:
It looks like your very close to 90 degrees at half lift...I would screw your adjusters in about 5 turns and shorten the pushrods. You have too much of that adjusting screw sticking out there. GOOD JOB!!!. One can do amazing things with a belt sander and a flat bastard.

Thank you for the advice.

I'd hate to draw file the rocker blocks. It would take forever. I haven't cut the PR's yet so your post is timely.

I still need to lap the valves. So I have a few more day's before I cut the PR's.

I'll adjust the screw and see where I end up.

All this information. Should help someone down the road.


Helped me already, have been looking to get the Scat 1.4 rockersb, will be going in 043 heads and this thread has been a great source of info.

Thinking about the ACN pushrods as well, even though they say they are the right fitment, has anyone any real life experience with them?


How close are they? I'm guessing there is still a good chance they will need to be cut to the right length??



"These are the proper length to install SCAT's great 1.4 Ratio Rocker Arms (20195) onto your engine, IF you had original length PRs to begin with!"

Will be going into a stock engine with only twin carbs and exhaust changed so far.
I know this is along time ago but I could use the answer to this question. How did the precut PR work?
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PostPosted: Thu May 20, 2021 5:04 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

About a 2 years ago I purchased a set of ACN's Heavy Duty Aluminum Pushrods, Dual Tapered, Set Cut to Custom Length (Assembled) to my specs and they are good, no problems. They all measured out good and work good. I had to wait quite a while to receive them after ordering.

Marty
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PostPosted: Thu May 20, 2021 5:46 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

You can bevel the edges of the pads on the head too. The rocker blocks are narrower than the pads on the head...this provides clearance when you shave the blocks
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PostPosted: Sat Jul 24, 2021 5:13 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

So lets add to this thread Very Happy Cool Very Happy


The pushrod and adjuster are pin straight at half lift, correct?

1.4s with a K-8

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PostPosted: Sat Jul 24, 2021 5:40 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

Go to page three 2/3s the way down you can get a feel for what is close to correct on the rocker geo.
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PostPosted: Tue Aug 03, 2021 2:39 pm    Post subject: Re: Understanding 1.4 slipper foot rocker geo. Not elephant foot. Reply with quote

I have been working on my 2332 build trying to get Scat 1.4 rocker geometry correct. I have shaved 0.100 off the rocker blocks. With 0.100 off the block I now have the top of the lash cap inline with the center of the rocker shaft at half lift - 90 degrees to valve. The push rod is inline with the adjuster at half lift.

Below are pictures of the swipe. It starts low a moves up to exactly center of the lash cap at half lift, then stays there tell full lift. Is this OK?

Picture after two full rotations
Image may have been reduced in size. Click image to view fullscreen.


Picture with swipe pattern “cleaned up” so you can tell the full sweep.
Image may have been reduced in size. Click image to view fullscreen.


Am I where I need to be?

…and the top of the swipe (shinny area) is truly half way up the lash cap. Pictures make it look lower than that.
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