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BFB Samba Member
Joined: November 03, 2014 Posts: 1693
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Posted: Sat Sep 18, 2021 4:21 pm Post subject: old sig erson ratios 2.1??? |
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I have a couple sets of old erson ratio rockers , don't know what size but I always assumed they were 1.25's . I grabbed one the other day just out of curiosity I measured one a little half-assedly with a tape measure and came up with 1 7/8" from shaft center to valve contact and 7/8 from shaft center to pushrod adjuster center. 1 7/8 and 7/8 converted to decimals of 1.875 and .875, then you'd divide the valve side by the pushrod side right? and I got 2.14. well that ain't right at all. what the hell did I do wrong? I figured a tape measure would get me in the ballpark but I don't think I see a hotdog or beer vendor anywhere around here!
I'm sure I did something I'll feel stupid for but this'll give us something to talk about and ppl to search _________________ Forced induction can overcome a lot of obsticles that gets in it's way
"You are the Engineer and the Mechanic.
Build it your way not the way someone else does it. Their way might not work for you." - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
“ The monkey see monkey do mentality seems to run deep in VW people. "Gene Berg said it was so 30 years ago so thats the way it is" “ - bdkw1 |
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Dan Ruddock Samba Member
Joined: October 25, 2012 Posts: 3574 Location: Sarasota, in my adopted state of Florida
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Posted: Sat Sep 18, 2021 5:42 pm Post subject: Re: old sig erson ratios 2.1??? |
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You determine the rocker ratio by measuring how much lift you get. |
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74 Thing Samba Member
Joined: September 02, 2004 Posts: 7374
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Posted: Sat Sep 18, 2021 8:19 pm Post subject: Re: old sig erson ratios 2.1??? |
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1.5s most likely |
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modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
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Posted: Sat Sep 18, 2021 8:27 pm Post subject: Re: old sig erson ratios 2.1??? |
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If I add you measurements... your rocker is about .300" too long. |
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BFB Samba Member
Joined: November 03, 2014 Posts: 1693
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Posted: Sun Sep 19, 2021 8:10 am Post subject: Re: old sig erson ratios 2.1??? |
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the measuring process and math formula is correct though, right?
if so I'll re measure but a little more accurately this time.. _________________ Forced induction can overcome a lot of obsticles that gets in it's way
"You are the Engineer and the Mechanic.
Build it your way not the way someone else does it. Their way might not work for you." - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
“ The monkey see monkey do mentality seems to run deep in VW people. "Gene Berg said it was so 30 years ago so thats the way it is" “ - bdkw1 |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7182 Location: Videbaek Denmark
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Posted: Sun Sep 19, 2021 11:03 am Post subject: Re: old sig erson ratios 2.1??? |
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richardcraineum wrote: |
the measuring process and math formula is correct though, right?
if so I'll re measure but a little more accurately this time.. |
As such yes. But it depends heavily on the PR to rocker arm angle and also the rocker arm to valve angle. If you begin measuring it IRL you will notice that the ratio varies a lot if you compare 0-0,200", 0,200-0,400" and 0,400"& up. On top of that the PR to rocker arm angle plays a significant role too.
The general consensus is to measure at full lift. If you notice what people write here and there, they get variations from 1,4 to 1,46 on a set of 1,4 rockers. _________________ https://www.thesamba.com/vw/forum/viewtopic.php?t=435993 |
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evanfrucht Samba Member
Joined: July 24, 2016 Posts: 2180 Location: Laurel Canyon, CA
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Posted: Sun Sep 19, 2021 11:23 am Post subject: Re: old sig erson ratios 2.1??? |
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You don't just divide the distance from center to contact point on a loose rocker shaft floating around the shop. There is more to take into account.
You can get a basic idea but you need to be measuring it at the right place and while installed. At that point a dial indicator will give you a more accurate result...
I think the biggest rocker Sig Erson ever made they referred to as a 1.6, but it might if been 1.5.
How the advertised rocker ratio actually plays out in real life also depends on the rocker geometry and your specific heads. _________________ 1967 Bug ( the daily rod )
1964 Fury Wagon ( the pavement shredder ) |
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BFB Samba Member
Joined: November 03, 2014 Posts: 1693
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Posted: Sun Sep 19, 2021 12:38 pm Post subject: Re: old sig erson ratios 2.1??? |
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evanfrucht wrote: |
You don't just divide the distance from center to contact point on a loose rocker shaft floating around the shop. There is more to take into account.
You can get a basic idea but you need to be measuring it at the right place and while installed. At that point a dial indicator will give you a more accurate result...
I think the biggest rocker Sig Erson ever made they referred to as a 1.6, but it might if been 1.5.
How the advertised rocker ratio actually plays out in real life also depends on the rocker geometry and your specific heads. |
I understand where a couple of you are going with this and it's true but at the same time it's really splitting hairs, I'm only trying to figure the ratio of the rocker itself ( advertised ). I mean if you have a lever and on one side of the fulcrum it's a foot long and the other side of the fulcrum it's two feet long then you'd say that lever is a 2:1 . now how someone may install or use that lever will cause a variation to that ratio, sure. but all were trying to do here is figure out the "lever's" ratio. if you can't figure out the "lever's" ratio then manufacturers couldn't sell rockers as 1.1:1, or 1.25, or 1.5, they'd have to list them as "we don't even know a close ratio , could be from 1:1 to 3:1 depending on your installation ". I know that's an exaggeration but at the same so is saying that you have to build an engine just to figure out an unknown rockers ratio.
by this same train of thought you'd say that a person can't just measure a loose cam floating around the shop to get the lobe lift. yes there will be variations according to the rest of the valvetrain used but you can absolutely measure its lift. maybe other specs too but I don't know, never done more than lift _________________ Forced induction can overcome a lot of obsticles that gets in it's way
"You are the Engineer and the Mechanic.
Build it your way not the way someone else does it. Their way might not work for you." - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
“ The monkey see monkey do mentality seems to run deep in VW people. "Gene Berg said it was so 30 years ago so thats the way it is" “ - bdkw1 |
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evanfrucht Samba Member
Joined: July 24, 2016 Posts: 2180 Location: Laurel Canyon, CA
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Posted: Sun Sep 19, 2021 12:51 pm Post subject: Re: old sig erson ratios 2.1??? |
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I get your point, what I'm basically saying is that is actually hard to do without mocking up on a head or engine (not sure if you did that.) Also something a little stiffer than tape might work better. _________________ 1967 Bug ( the daily rod )
1964 Fury Wagon ( the pavement shredder ) |
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modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
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Posted: Sun Sep 19, 2021 1:51 pm Post subject: Re: old sig erson ratios 2.1??? |
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I can show how to measure rocker ratio if you would like.
I think it would be best to make an illustration.
"What did I do wrong" well, probably a few things but I don't know.
I had a similar conversation with my good buddy yesterday showing him ways to setup things on his CNC machine.
I know most ALL of the tricks, so I showed him quite a few and that should help BUT, adds a little complication which you have to get used to.
but I was amazed to see how good he was at "eyeballing it".
His eyeballs are really good tho. Better than 20-20, mine sure aren't |
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modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
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Posted: Sun Sep 19, 2021 2:51 pm Post subject: Re: old sig erson ratios 2.1??? |
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Measure it like this, and you will find the intended ratio.
This is also wrong, but, it is more right.
How to measure the actual instantaneous ratio of a wrongly designed rocker might be another discussion, or it might not. But for that you will need to know the location of the valve and pushrod.
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BFB Samba Member
Joined: November 03, 2014 Posts: 1693
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Posted: Mon Sep 20, 2021 5:52 pm Post subject: Re: old sig erson ratios 2.1??? |
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evanfrucht wrote: |
I get your point, what I'm basically saying is that is actually hard to do without mocking up on a head or engine (not sure if you did that.) Also something a little stiffer than tape might work better. |
yeh, I actually thought yall might get a kick out of the tape measure thing... _________________ Forced induction can overcome a lot of obsticles that gets in it's way
"You are the Engineer and the Mechanic.
Build it your way not the way someone else does it. Their way might not work for you." - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
“ The monkey see monkey do mentality seems to run deep in VW people. "Gene Berg said it was so 30 years ago so thats the way it is" “ - bdkw1 |
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Back to top |
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