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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 didnít wonít 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 didnít shave the blocks. Once the shutdown is over at work, Iíll shave them down 0.100Ē and post a pic. Thank you all for the help, I just donít 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 Iím pretty lit too, but is that at half lift, or 0 lift? If half lift Iíll need to shave the blocks down ~0.120Ē but if at 0 lift I need to install .030Ē shims.
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rugblaster
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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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rodeking
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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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bugguy1967
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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 ďrodeking methodĒ 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 rodekingís 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 (0.157Ē)
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bugguy1967
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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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Onceler
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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. Iíll 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 Ruddockís beehives Iím gonna run.
But Iím 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 rodekingís 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 (0.157Ē)



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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