What is the intake valve size and engine CID per cylinder on that engine?
128 my take, anybody see it like this ?
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Re: 128 my take, anybody see it like this ?
Re: 128 my take, anybody see it like this ?
LCA = LSA.Tom68 wrote: ↑Wed Sep 21, 2022 12:33 amThis is all I've seen of 128.skinny z wrote: ↑Tue Sep 20, 2022 9:21 pm
128 is to define the lobe separation angle. If we follow the originator of the 128 rule and continue on to the same author's TM program, you'll find that 4 degrees tends to be built into the cam specs.
What did 128 determine for an LSA with a 1.72" valve, your CID and CR?
128.jpg
As in Lobe Centreline Angle is also described as Lobe Seperation Angle.
Not sure if that was a point of confusion here but it often is elsewhere.
Kevin
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Re: 128 my take, anybody see it like this ?
LSA is just the average angle of the intake centerline and exhaust centerline. You could have the same LSA with many different centerline anglesskinny z wrote: ↑Wed Sep 21, 2022 8:33 amLCA = LSA.Tom68 wrote: ↑Wed Sep 21, 2022 12:33 amThis is all I've seen of 128.skinny z wrote: ↑Tue Sep 20, 2022 9:21 pm
128 is to define the lobe separation angle. If we follow the originator of the 128 rule and continue on to the same author's TM program, you'll find that 4 degrees tends to be built into the cam specs.
What did 128 determine for an LSA with a 1.72" valve, your CID and CR?
128.jpg
As in Lobe Centreline Angle is also described as Lobe Seperation Angle.
Not sure if that was a point of confusion here but it often is elsewhere.
-Bob
Re: 128 my take, anybody see it like this ?
I'm not entirely certain although I believe the 128 application is for a symmetrical lobe. In that case, there's a clearly defined centerline isn't there? And the math is much simpler.hoffman900 wrote: ↑Wed Sep 21, 2022 8:50 amLSA is just the average angle of the intake centerline and exhaust centerline. You could have the same LSA with many different centerline angles
Kevin
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Re: 128 my take, anybody see it like this ?
It is, but I’m not sure why “LCA” is used other than different marketing terminology. LSA is just an average of two centerlines, it doesn’t tell you anything.skinny z wrote: ↑Wed Sep 21, 2022 8:53 amI'm not entirely certain although I believe the 128 application is for a symmetrical lobe. In that case, there's a clearly defined centerline isn't there? And the math is much simpler.hoffman900 wrote: ↑Wed Sep 21, 2022 8:50 amLSA is just the average angle of the intake centerline and exhaust centerline. You could have the same LSA with many different centerline angles
-Bob
Re: 128 my take, anybody see it like this ?
LCA equals installed position, LSA ground into cam.
LSA Lobe separation angle between intake and exhaust centerlines, install wherever you like.
LCA Lobe centreline angle, one for exhaust, one for intake, defined when you degreed the cam in, add the two and halve them equals LSA.
That's the way I work with it anyways.
If the formula is for LSA, it does it without any exhaust information.
Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
Re: 128 my take, anybody see it like this ?
So, when going through a catalogue and coming across this...hoffman900 wrote: ↑Wed Sep 21, 2022 9:10 amIt is, but I’m not sure why “LCA” is used other than different marketing terminology. LSA is just an average of two centerlines, it doesn’t tell you anything.skinny z wrote: ↑Wed Sep 21, 2022 8:53 amI'm not entirely certain although I believe the 128 application is for a symmetrical lobe. In that case, there's a clearly defined centerline isn't there? And the math is much simpler.hoffman900 wrote: ↑Wed Sep 21, 2022 8:50 am
LSA is just the average angle of the intake centerline and exhaust centerline. You could have the same LSA with many different centerline angles
...it doesn't mean anything?
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Kevin
Re: 128 my take, anybody see it like this ?
That's right.
It takes into account a few basic parameters to establish the spread between centrelines. This is as ground into the cam.
Where you install the intake centerline is entirely up to the individual.
Kevin
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Re: 128 my take, anybody see it like this ?
Nope. That could be;skinny z wrote: ↑Wed Sep 21, 2022 9:23 amSo, when going through a catalogue and coming across this...hoffman900 wrote: ↑Wed Sep 21, 2022 9:10 amIt is, but I’m not sure why “LCA” is used other than different marketing terminology. LSA is just an average of two centerlines, it doesn’t tell you anything.
Screenshot_20220921-071910~2.png
...it doesn't mean anything?
100ICL and 114ECL
105ICL and 109ECL
107ICL and 107ECL
109ICL and 105ECL
Etc
All would run completely different.
Guys, we’ve been through this a million times here and many have of you have been around long enough to see this discussed many of those times.
-Bob
Re: 128 my take, anybody see it like this ?
Yes. But now you've thrown duration into the mix.hoffman900 wrote: ↑Wed Sep 21, 2022 9:28 amNope. That could be;skinny z wrote: ↑Wed Sep 21, 2022 9:23 amSo, when going through a catalogue and coming across this...hoffman900 wrote: ↑Wed Sep 21, 2022 9:10 am
It is, but I’m not sure why “LCA” is used other than different marketing terminology. LSA is just an average of two centerlines, it doesn’t tell you anything.
Screenshot_20220921-071910~2.png
...it doesn't mean anything?
100ICL and 114ECL
105ICL and 109ECL
107ICL and 107ECL
109ICL and 105ECL
Etc
All would run completely different.
Guys, we’ve been through this a million times here and many have of you have been around long enough to see this discussed many of those times.
I'm talking, as the 128 formula describes, how much spread there should be. The duration is another spec altogether.
The 128 formula does not provide a spec and this discussion, as per the title of the thread, is about 128. Nothing else.
It only serves as as a guide for what in this case is a finite application and that has proven empirically to be effective.
It would be up to the user to take this LSA and then also determine what duration, centrelines, lift, et al will provide the results sought after.
Make of it what you will.
Last edited by skinny z on Wed Sep 21, 2022 9:46 am, edited 1 time in total.
Kevin
Re: 128 my take, anybody see it like this ?
The OEM factory stock 2bbl base 265-283 sbc engines the stock hyd cam had 107° LSA. 172/172 .333" .333"
70's era. 366/427 hd truck camshaft. 103.5 LSA
80's era 267/305 cam 109 LSA
Last edited by F-BIRD'88 on Wed Sep 21, 2022 10:02 am, edited 1 time in total.
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Re: 128 my take, anybody see it like this ?
I’m making of it exactly what it is. A rule of thumb for car show and street rodders, with 350ish ci inline valve 2 valvers and nothing more.skinny z wrote: ↑Wed Sep 21, 2022 9:40 amYes. But now you've thrown duration into the mix.hoffman900 wrote: ↑Wed Sep 21, 2022 9:28 amNope. That could be;
100ICL and 114ECL
105ICL and 109ECL
107ICL and 107ECL
109ICL and 105ECL
Etc
All would run completely different.
Guys, we’ve been through this a million times here and many have of you have been around long enough to see this discussed many of those times.
I'm talking, as the 128 formula describes, how much spread there should be. The duration is another spec altogether.
The 128 formula does not provide a spec and this discussion, as per the title of the thread, is about 128. Nothing else.
It only serves as as a guide for what in this case is a finite application has proven empirically to be effective.
It would be up to the user to take this LSA and then also determine what duration, centrelines, lift, et al will provide the results sought after.
Make of it what you will.
-Bob
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- HotPass
- Posts: 3468
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Re: 128 my take, anybody see it like this ?
They also had terrible cylinder heads. ICL 98-102 is typical on old British stuff. On one we built, for racing, we like around 104ICL and around 104-106ECL.
I know of an A-Series that is making 126hp/L naturally aspirated on gasoline with around a 105-107ICL.
Horses for courses.
-Bob
Re: 128 my take, anybody see it like this ?
Precisely.hoffman900 wrote: ↑Wed Sep 21, 2022 9:46 amI’m making of it exactly what it is. A rule of thumb for car show and street rodders, with 350ish ci inline valve 2 valvers and nothing more.skinny z wrote: ↑Wed Sep 21, 2022 9:40 amYes. But now you've thrown duration into the mix.hoffman900 wrote: ↑Wed Sep 21, 2022 9:28 am
Nope. That could be;
100ICL and 114ECL
105ICL and 109ECL
107ICL and 107ECL
109ICL and 105ECL
Etc
All would run completely different.
Guys, we’ve been through this a million times here and many have of you have been around long enough to see this discussed many of those times.
I'm talking, as the 128 formula describes, how much spread there should be. The duration is another spec altogether.
The 128 formula does not provide a spec and this discussion, as per the title of the thread, is about 128. Nothing else.
It only serves as as a guide for what in this case is a finite application has proven empirically to be effective.
It would be up to the user to take this LSA and then also determine what duration, centrelines, lift, et al will provide the results sought after.
Make of it what you will.
Kevin