Comp XE268H v Crow 18619 - 318

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Bewy said:
Barra,

If you really wanted to see what worked best in your engine, you would probably have to try a few cams & spend the $$$. DV did just that. Tested over 19,000 cam combinations at Crane cams....& more. From that he derived the 128 rule, which you will find on the web. Works for street CRs & parallel valve heads.

The last thing you want is a cam with 112-114 LSA. Too wide. 106 would probably be ideal but a shelf grind with short enough duration might be hard to find.
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The 128 rule is for finding the ideal LCA, not LSA.

I'd agree that in this case, with the OP's goals and engine combo, the narrower LSA is more ideal. A wider LSA has it's place, but would depend on the combo and the goal.
 
Bakerlite said:
Why isn't everyone using Isky? or Comp, or a dozen plus other grinders??
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Most people get married to a brand, for various reasons, most of which are similar to why people drink Asolut(ly garbage) vodka.
 
roccodart440 said:
The 128 rule is for finding the ideal LCA, not LSA.

I'd agree that in this case, with the OP's goals and engine combo, the narrower LSA is more ideal. A wider LSA has it's place, but would depend on the combo and the goal.
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I've seen some of David vizard's videos and have a book he wrote, he talks LCA alot not LSA and have read in the forums that a LCA and LSA are the same.
 
volaredon said:
I've seen some of David vizard's videos and have a book he wrote, he talks LCA alot not LSA and have read in the forums that a LCA and LSA are the same.
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LCA and LSA are not the same.


LSA =LOBE SEPARATION ANGLE. LSA is ground into the cam during manufacturing.

LCA =LOBE CENTER ANGLE. Lobe center angles can be changed by indexing the cam when degreeing it in, hence advancing or retarding the cam. Keep in mind some cams are up to 4 degrees advanced when installed "dot to dot"
 
I am far far from a cam expert, cam numbers make my head spin. Just going by what was said on a few forums that I frequent.
 
volaredon said:
cam numbers make my head spin
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You should look up old posts by a “missing in action” member, Wyrmrider I think it is, I refer to him as “The Chrysler Cam Crusader” That guy had the numbers I gotta tell ya! He knew his **** for sure, likely made many heads explode!:eek:
 
Rocco, post #76, hate to break it to you pal but LCA & LSA are the same. So is LDA. Different nomenclature for the same thing.
All three refer to the angular measurement between the exh lobe & int lobe at max lobe lift.
 
Bewy said:
Rocco, post #76, hate to break it to you pal but LCA & LSA are the same. So is LDA. Different nomenclature for the same thing.
All three refer to the angular measurement between the exh lobe & int lobe at max lobe lift.
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Here is an article by comp cams about this topic

"The last thing we will discuss is the difference between intake centerline and lobe separation angle. These two terms are often confused. Even though they have very similar names, they are very different and control different events in the engine."

COMP Cams Valve Timing Tutorial.
 
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Rocco,
That article is NOT about this topic. This topic is about LSA, LCA & LDA.
ICL is another topic.
 
Bewy said:
Rocco, post #76, hate to break it to you pal but LCA & LSA are the same. So is LDA. Different nomenclature for the same thing.
All three refer to the angular measurement between the exh lobe & int lobe at max lobe lift.
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LSA and LCA are not the same..
Tell me.. how are you going to change the LSA (Lobe Separation Angle) between an intake and an exhaust lobe on an single cam engine? They are fixed, so you can't.
LCA (Lobe Center Angle) is the angle in degrees that the cam is aligned with the crankshaft, obviously this can be changed, as in when degreeing in the cam on the intake center line or center of the nose of the lobe.
Or am I just a Dope?
It's people like you who take a simple basic concept and make a total mess out of it, for no reason at all..
 
No, you are wrong & for the umpteenth time LSA, LCA [ & LDA ] are the same thing, just different words used. Like calling a lifter a tappet....
Neither of the three have anything to do with the alignment of the cam to the crank.
If the cam has a 108 LSA [ or LCA or LDA ], it still has that angle sitting on a table & nowhere near a crank. It is in cam degrees & is ground into the cam for the cams in this thread.
LCA cannot be changed without having the cam re-ground.
You are confusing ICL [ int centre line ] with LCA. ICL is measured in crank degrees. ICL can be changed by moving the cam relative to the crank using multi slot sprockets etc. If you add the ICL to the ECL & divide by two, you get the LSA.
 
Bewy said:
No, you are wrong & for the umpteenth time LSA, LCA [ & LDA ] are the same thing, just different words used. Like calling a lifter a tappet....
Neither of the three have anything to do with the alignment of the cam to the crank.
If the cam has a 108 LSA [ or LCA or LDA ], it still has that angle sitting on a table & nowhere near a crank. It is in cam degrees & is ground into the cam for the cams in this thread.
LCA cannot be changed without having the cam re-ground.
You are confusing ICL [ int centre line ] with LCA. ICL is measured in crank degrees. ICL can be changed by moving the cam relative to the crank using multi slot sprockets etc. If you add the ICL to the ECL & divide by two, you get the LSA.
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I'll have to re educate all the Cam Grinders I know:rolleyes:
I guess you just can't be told, can you. The reason LSA is spelt different to LCA is because they mean two different things.
LSA refers to the angle between two lobes, LCA is a reference to only one lobe.
Separation.....Center... use a Dictionary..
ILCA, ELCA, ILCD, ELCD... See I can make it even muddier and more of a mess.
I see David has a new book out, but somehow I think you already have a copy.

Knobend.JPG
 
The term Lobe Center and Lobe Separation were defined / Clarified as two separate things years ago, BECAUSE of the confusion they caused with the non College educated crowd..
Clay Smith. Didn't even know they still existed. Are they just selling stickers and T shirts these days?
 
Have a little look at this. Here you can see Separation and Centerline .
Camstuff.JPG
 
Bakerlite said:
The reason LSA is spelt different to LCA is because they mean two different things.

View attachment 1715907284
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I DM'd an engine builder many of us know, who calls in cam specs, he doesn't ask for them. He assured me of three things; one that LSA and LCA are different, two, that everyone gets wet in a pissing contest, and three, that he has learned to stay dry.
 
Wow, this is really groundbreaking and enlightening with all this nonsense about LSA and LCA. :rolleyes::rolleyes::rolleyes:

If someone doesn’t know the difference between separation and centerline it’s because they read it somewhere as a misprint or an oversight, it was mislabeled and it wasn’t properly proofread and corrected by the writer and/or editor before going to print. I have the David Vizard books with all his charts and mislabeling of LSA as LCA.
We all use LSA and ICL and perhaps check the ECL. But if you want to start a new trend use ILCA and ECLA, ETA, TDS, TSA, OCD, PTSD.....:steering:
 
Bakerlite said:
Have a little look at this. Here you can see Separation and Centerline .
View attachment 1715907290
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The lobe center angle and the lobe separation angle are one in the same. Maybe it's how you fellers down there use different terminology. You're talking about the Intake Center line, not the lobe center angle. The lobe center angle is the distance from the peak of the intake and exhaust lobes. Just the same as the Lobe separation angle. The intake center line is the comparison of the intake lobe peak TO the lobe separation angle. I don't know how to make it any plainer. Again, maybe we have some language barrier going on. I don't know.
 
Rusty,
If your claiming that lobe center angle is between the intake and exhaust, then it would be called "centers" angle.
"Centers" ,Plural, because it's referencing two lobes in the equation.
But it's called "Center angle" ,Singular, because it's only referencing one lobe.
But why should I care, I'm not payed to educate here.
 
Bakerlite said:
Rusty,
If your claiming that lobe center angle is between the intake and exhaust, then it would be called "centers" angle.
"Centers" ,Plural, because it's referencing two lobes in the equation.
But it's called "Center angle" ,Singular, because it's only referencing one lobe.
But why should I care, I'm not payed to educate here.
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sounds like the same thing as installed centerline. Is it not?
 
roccodart440 said:
he has learned to stay dry.
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Two idiots will always agree with each other before they agree with an experienced person.
I think I'll keep dry by just letting the idiots infect each other, they don't pay my bills..
 
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