Popular Hotrodding says 103 LSA??

[HT413]

Hey fellas, just doing my normal evening engine research and I came across this excellent cam selection article from Popular Hotrodding. They suggest that overlap is the FIRST thing you need to figure on when selecting a cam and the next is LCA (LSA being another way of saying LCA).

http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/viewall.html

Well, when you use their LCA chart, I come up with 103 for a street 440 with oem valve size (about the same for my 413).

Seriously, 102-103 LCA?? Most guys recommend 110 to 112 for big block mopars, though some cams like the whiplash go to 107. Does the long rod / high mopar rod ratio come into play here and require a longer LCA than the article suggests??? (Just guessing.) I know I'm not saying anything about my combo (though I've talked about it enough that you guys are probably sick of it). But the article suggests that this is good for any street / strip motor with that displacement and intake valve size.

What do you think?


Lobe Centerline Angle Determination Chart
"To use this chart, first establish the number of cubes in the cylinder per inch of valve diameter. To get this number, divide the engine displacement by the number of cylinders, then by the intake valve diameter..."

 

[Tempest 455]

Trust me, you are not going to like a 103 on a street car. I would stick with 110 or more.

 

[BeastlyBirdie]

LSA is seperation, LCA is (for intake) degrees after top dead referring to crankshaft. On exhaust, it is before top dead. This has to do with advancing/retarding the camshaft.
In other words, a 108° spun 4° advanced comes in at 104°.

 

[super-bee_ski]

I think this last sentance is the "key"
"But the article suggests that this is good for any street / strip motor with that displacement and intake valve size"

Street/Strip is just that,

As you pointed out, it seems radical...

 

[Cranky]

I'm no cam guru but the first thing I look at is where the intake valve opens at the recommended installation. If I don't like what I see there for what I'm building, I move on.

 

[HT413]

LSA is seperation, LCA is (for intake) degrees after top dead referring to crankshaft. On exhaust, it is before top dead. This has to do with advancing/retarding the camshaft.
In other words, a 108° spun 4° advanced comes in at 104°.

That's kinda what I was thinking too, maybe they really mean intake centerline. But if you read the article, they really do mean the LSA that the cam is ground on, not intake centerline.

- - - Updated - - -

Trust me, you are not going to like a 103 on a street car. I would stick with 110 or more.

I hear ya there. I kinda figured it would point me more toward 110 vs 112 or what have you, heck, maybe even as low as 108. But like you said, there's gotta be a reason I've never seen an off the shelf cam ground at 103 for these motors.

 

[ply64post]

cam selection

I call the cam grinder and ask there opinion.Give them the specs on the car,weight,trans,gears,engine specs,street,strip or combination of both and have them tell you what cam, valve components to use with your combination.Making the the wrong selection can make for money that is lost and plenty of extra work! Usally performance suffers with the wrong selection and you end up an unhappy camper.Made that mistake myself 40+ years ago.The 2 things that happens is over camming and wrong carb.Just don't like to see people spend money for the wrong parts,the money is hard to gather for projects even with the right parts.With the tech we have today things have changed with cam grinds compared to years ago.

Sorry just my 2 cents

Jeff

 

[HT413]

I call the cam grinder and ask there opinion.Give them the specs on the car,weight,trans,gears,engine specs,street,strip or combination of both and have them tell you what cam, valve components to use with your combination.Making the the wrong selection can make for money that is lost and plenty of extra work! Usally performance suffers with the wrong selection and you end up an unhappy camper.Made that mistake myself 40+ years ago.The 2 things that happens is over camming and wrong carb.Just don't like to see people spend money for the wrong parts,the money is hard to gather for projects even with the right parts.With the tech we have today things have changed with cam grinds compared to years ago.

Sorry just my 2 cents

Jeff

I just happened to come across this article, which otherwise seems very good, and figured I'd get your opinions just out of curiosity, I really wasn't planning on going with a 103.

But I do appreciate the advice. I did call a cam grinder, (lunati, hughes and howards). Howards and hughes suggested 106 and 107 LCA's to maintain cylinder pressure in my low compression 413. Lunati suggested 110.

 

[ply64post]

I just happened to come across this article, which otherwise seems very good, and figured I'd get your opinions just out of curiosity, I really wasn't planning on going with a 103.

But I do appreciate the advice. I did call a cam grinder, (lunati, hughes and howards). Howards and hughes suggested 106 and 107 LCA's to maintain cylinder pressure in my low compression 413. Lunati suggested 110.

HT 413

There are lots opinions thats why I always check with the cam people.As far as the articles there is good information out there also.I feel better to just varify my selection with the cam grinder.I see you got some different selections for your application from different grinders also. I am sure that there are tried and true good combinations out there .

Jeff

 

[BeastlyBirdie]

If they are referring to separation as lobe centerline, they are incorrect, and at that point I wouldn't be following any of the advice. The chart you posted however, is for centerline. With a 440 running 2.14 valve it works out at about 104°.

 

[HT413]

If they are referring to separation as lobe centerline, they are incorrect, and at that point I wouldn't be following any of the advice. The chart you posted however, is for centerline. With a 440 running 2.14 valve it works out at about 104°.

Yeah, if you look at it that way, it makes so much more sense. I'm guessing you have to be right. That way 104 centerline is a 110 cam advanced 6 degrees. That might be more than some would suggest, but seems much more reasonable than a 104 LSA cam I'd think.

 

[Cranky]

Damon Kuhn over at DiamondBack is the guy I talk to when I need cam advice....

 

[tallhair]

Damon Kuhn over at DiamondBack is the guy I talk to when I need cam advice....

Filed. Under "If Cranky has a cam guy HE calls I'm saving it"

 

[Cranky]

filed. Under "if cranky has a cam guy he calls i'm saving it"

lol!

 

[HT413]

Filed. Under "If Cranky has a cam guy HE calls I'm saving it"

About sums it up. Never heard of the guy but i'm gonna call this week. Cranky, happen to have some contact info? Or something i can google?

 

[Cranky]

https://www.google.com/#q=Damon+Kuhn+diamondback+engines&spell=1 He is/was COO of ROON Motors but I haven't heard much about that lately
http://peswiki.com/index.php/Article:Ronn_Motors'_Scorpion_using_Hydrogen_Booster

His web site diamondbackengines.com is in the process of being moved to a new server. Kinda thought it would be done by now tho. He's also a member here and goes by Fugly which is the name of his NSS race car.

 

[tallhair]

Thanks Crankster. File updated

 

[HT413]

https://www.google.com/#q=Damon+Kuhn+diamondback+engines&spell=1 He is/was COO of ROON Motors but I haven't heard much about that lately
http://peswiki.com/index.php/Article:Ronn_Motors'_Scorpion_using_Hydrogen_Booster

His web site diamondbackengines.com is in the process of being moved to a new server. Kinda thought it would be done by now tho. He's also a member here and goes by Fugly which is the name of his NSS race car.

That 2nd link was pretty wild.

 

[Meep-Meep]

I agree the description sounds like the lobe separation angle rather than the intake lobe centerline spec. I have to wonder if someone got the terminology mixed up while writing this article. I can see an installed intake CL of 104 but an LSA of 108, 112, 114, etc..

 

[Ryguytoodry]

Generally, lower = more power for a n/a motor. Problem is that it runs choppier the lower you go, making it hard to drive on the street. If it was a boosted motor it likes higher, I was going to run a 114 in my slant before I decided on keeping the stock cam until I run more boost.