Highervalve lift with shims - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Rabrooks · 03-29-2022, 05:23 PM

Has anyone ever tried to get a little more valve lift by adding small shims under the post that tbe rocker rests on? It seems reasonable that raising the resting place of the rocker would translate into higher lift. Obviously, thia would need to be a small amount and still keep valve train geometry in good shape. Lmk

Tokay444 · 03-29-2022, 05:35 PM

lol

soundman98 · 03-29-2022, 10:58 PM

how does moving the fulcrum up alter how much lift the cam shaft provides?

Tokay444 · 03-30-2022, 08:33 AM

Quote:

Originally Posted by soundman98

how does moving the fulcrum up alter how much lift the cam shaft provides?

He's not talking about moving the fulcrum.
What he is talking about is removing lash.
Op, if you shim them enough that they're opened all the time, that will reduce pumping losses.

Lantanafrs2 · 03-30-2022, 11:13 AM

Nice backfires too

Breadman · 03-30-2022, 11:26 AM

The valves wouldnt close all the way then...
They also make bigger cams for just this reason

NoHaveMSG · 03-30-2022, 12:54 PM

Lift would still be the same, as pointed out already, you are just changing the lash.

Tokay444 · 03-30-2022, 02:01 PM

I say go for it because, “you don’t know until you know.”

Rabrooks · 03-30-2022, 08:49 PM

I thought the rocker ratio might provide a small advantage after altering the geometry. Oh well. A passing thought

NoHaveMSG · 03-30-2022, 09:10 PM

Quote:

Originally Posted by Rabrooks

I thought the rocker ratio might provide a small advantage after altering the geometry. Oh well. A passing thought

Realizing now I miss read the intent of what you where trying to do. Still wouldn't do it as I have had a rocker arm eject on an FA20 before. Raising the pivot seems like it would make it more unstable to me. It is not as simple as changing the rocker ratio on a pushrod motor.

makinen · 03-31-2022, 12:59 AM

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Will raising the pivot point (red arrows) result in higher lift? The shim at the top of valve stem should changed accordingly.

NoHaveMSG · 03-31-2022, 12:33 PM

Quote:

Originally Posted by makinen

Will raising the pivot point (red arrows) result in higher lift? The shim at the top of valve stem should changed accordingly.

I don't think so. Since the fulcrum is on the end the length of the arm is the same.

03-29-2022, 05:23 PM	#1
Rabrooks Senior Member Join Date: Oct 2019 Drives: 2020 Subaru BRZ Location: Washington NC Posts: 110 Thanks: 7 Thanked 23 Times in 18 Posts Mentioned: 3 Post(s)	Highervalve lift with shims Has anyone ever tried to get a little more valve lift by adding small shims under the post that tbe rocker rests on? It seems reasonable that raising the resting place of the rocker would translate into higher lift. Obviously, thia would need to be a small amount and still keep valve train geometry in good shape. Lmk

03-29-2022, 10:58 PM	#3
soundman98 ProCrastinationConsultant Join Date: Sep 2013 Drives: '14 Ranger, '18 Tacoma 4Dr LB Location: chicago-ish Posts: 11,327 Thanks: 35,240 Thanked 13,677 Times in 6,782 Posts Mentioned: 98 Post(s)	how does moving the fulcrum up alter how much lift the cam shaft provides? __________________ "The time you enjoy wasting is not wasted time"

03-30-2022, 12:54 PM	#7
NoHaveMSG Senior Member Join Date: Jan 2018 Drives: Crapcan Location: Oregon Posts: 11,613 Thanks: 18,894 Thanked 16,900 Times in 7,691 Posts Mentioned: 112 Post(s)	Lift would still be the same, as pointed out already, you are just changing the lash. __________________ "Experience is the hardest kind of teacher. It gives you the test first and the lesson afterward." -Oscar Wilde.

03-30-2022, 02:01 PM	#8
Tokay444 Anti stance. Join Date: Feb 2016 Drives: 17 White 860. RCE Tarmac 2. RE-71RS Location: Not Canada Posts: 1,757 Thanks: 939 Thanked 1,026 Times in 582 Posts Mentioned: 10 Post(s)	I say go for it because, “you don’t know until you know.” Last edited by Tokay444; 03-30-2022 at 03:28 PM.

03-31-2022, 12:59 AM	#11
makinen Senior Member Join Date: Jan 2013 Drives: Toyota 86 Location: South Korea Posts: 281 Thanks: 143 Thanked 223 Times in 127 Posts Mentioned: 6 Post(s)	Will raising the pivot point (red arrows) result in higher lift? The shim at the top of valve stem should changed accordingly. __________________ /* Custom underbody panels and diffuser Custom electric water pump and PWM controller */

03-29-2022, 05:35 PM	#2
Tokay444 Anti stance. Join Date: Feb 2016 Drives: 17 White 860. RCE Tarmac 2. RE-71RS Location: Not Canada Posts: 1,757 Thanks: 939 Thanked 1,026 Times in 582 Posts Mentioned: 10 Post(s)	lol

03-30-2022, 11:13 AM	#5
Lantanafrs2 Senior Member Join Date: Jan 2018 Drives: 2013 frs red Location: South Florida Posts: 3,596 Thanks: 2,617 Thanked 3,163 Times in 1,704 Posts Mentioned: 6 Post(s)	Nice backfires too

03-30-2022, 11:26 AM	#6
Breadman Senior Member Join Date: Jul 2017 Drives: 2017 BRZ w/PP Location: Pa Posts: 1,027 Thanks: 51 Thanked 303 Times in 225 Posts Mentioned: 3 Post(s)	The valves wouldnt close all the way then... They also make bigger cams for just this reason

03-30-2022, 08:49 PM	#9
Rabrooks Senior Member Join Date: Oct 2019 Drives: 2020 Subaru BRZ Location: Washington NC Posts: 110 Thanks: 7 Thanked 23 Times in 18 Posts Mentioned: 3 Post(s)	I thought the rocker ratio might provide a small advantage after altering the geometry. Oh well. A passing thought

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