Cam Experts: Lobe Separation Angle?

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RustyRatRod said:
"The rest of the car" a lot of times is overlooked in the quest for a fast/quick drag car. I knew a guy when I worked at the local Chevy dealer. Had a STONE STOCK 270 HP 350 in a 70 Nova. He's gone now, but he was a super cool old school racer and was still doing it and enjoying it with his 2 grown sons. That car was dead consistent in the mid 12s from what I remember. I think it may have even gotten some 12.30s. The car itself was set up right and yet it sounded like grandmaw's grocery getter. He said it was the most consistent car he had ever raced. He was always winning, too.
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Most cars are a 10 flat drive train tied to a 12.50 chassis = 11 second car. The good stuff 60's like a 9.5 car and runs 10.50 on an 11.00 drive train. Stock elim guys are good at this type of deal.

Light car - 68 A body, old school 214/224 .450ish lift cam with a really nice set of 915 iron heads running 11.50. It wasn't the engine that made it go. SOS with some posters, look at what someone can do that isn't the norm... 10's with exh manifolds, wide LSA cam... yeaaaaa!!! have a cookie. LOL A lot of things are possible with enough time, effort, money, desire, testing.
 
Sig Erson on LSA

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Newbomb Turk said:
Ok, on that day, with whatever weather he made about 370 hp. That’s about 1.05 hp/cid.

Again, unless he doesn’t have headers or the headers are junk he’d make more power with different cam timing.

Of course we only know what you tell us.
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With that MPH he should be mid 11's with just a small hydraulic cam on a wide LSA is a street car. Reminds me of Mike Jones' boat engine with the small duration and wide LSA that makes LOADS of torque.
 
I saw the dyno HP figures for Jones' boat engine. That must be the most generous dyno ever made...
 
Now the tinkerer in my wants to swap my 340 cam out for something with a narrower LSA just to see. I haven't even got the car on the road yet.
One thing that interests me is the variables that Erson mentions and how they affect performance with varying LSA. For example what happens when you have exhaust manifolds vs headers?
 
1MeanA said:
Now the tinkerer in my wants to swap my 340 cam out for something with a narrower LSA just to see. I haven't even got the car on the road yet.
One thing that interests me is the variables that Erson mentions and how they affect performance with varying LSA. For example what happens when you have exhaust manifolds vs headers?
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more exhaust duration and a wider lsa
 
1MeanA said:
Now the tinkerer in my wants to swap my 340 cam out for something with a narrower LSA just to see. I haven't even got the car on the road yet.
One thing that interests me is the variables that Erson mentions and how they affect performance with varying LSA. For example what happens when you have exhaust manifolds vs headers?
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I wouldn’t move the LSA just to move it.

That’s hard to do.

If you post your bore, stroke, rod length, compression ratio, where you want peak torque and power I’ll run some numbers.
 
Newbomb Turk said:
I wouldn’t move the LSA just to move it.

That’s hard to do.

If you post your bore, stroke, rod length, compression ratio, where you want peak torque and power I’ll run some numbers.
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Its a stock 0.040" over 340 with stock O head 2.02 intake valves, compression bumped to 9.75:1, Edelbrock RPM intake and AVS 650, stock hp manifolds. I'm running 3.55s and stock 14 tires with 3.09 low 4 speed. Its just a cruiser.
 
Thanks for the comments on how LSA is calculated. Now that I understand intake/exhaust Lobe Center design provides the "average" for the LSA, I need to some more thoughts/feedback. Given that my 360 combo has the stock compression height .060 forged pistons (= lower compression), would I want a low degree intake lobe center (106/107?) and a higher exhaust lobe center (112/114) to build more initial cylinder pressure. Example, I see these 2 Oregon Cam regrinds that utilize these different LCs:
1369: 218/224 (.050), LC: 106 (Intake), 114 (Exhaust), Lift (1.5) .462(I)/.470(E)
1176: 230/236 (.050), LC: 106 (Intake), 114 (Exhaust), Lift (1.5) .488(I)/.491(E)
I'm leaning towards the 1176 for my combination: Duster, 360 - 340 X-heads, single plane, single plane intake, 750 DP, 3k stall, 727, 4.11 gears (8 3/4). I've always been of the opinion; I'd like a little more cam than not enough.
 
middleagecrisis said:
Thanks for the comments on how LSA is calculated. Now that I understand intake/exhaust Lobe Center design provides the "average" for the LSA, I need to some more thoughts/feedback. Given that my 360 combo has the stock compression height .060 forged pistons (= lower compression), would I want a low degree intake lobe center (106/107?) and a higher exhaust lobe center (112/114) to build more initial cylinder pressure. Example, I see these 2 Oregon Cam regrinds that utilize these different LCs:
1369: 218/224 (.050), LC: 106 (Intake), 114 (Exhaust), Lift (1.5) .462(I)/.470(E)
1176: 230/236 (.050), LC: 106 (Intake), 114 (Exhaust), Lift (1.5) .488(I)/.491(E)
I'm leaning towards the 1176 for my combination: Duster, 360 - 340 X-heads, single plane, single plane intake, 750 DP, 3k stall, 727, 4.11 gears (8 3/4). I've always been of the opinion; I'd like a little more cam than not enough.
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Cam 1176 with rhoads lifters would be nice
Stock rockers can be as bad as 1.35 not 1.5 @ 1.4 it turns into 462ish instead of 491
 
middleagecrisis said:
Thanks for the comments on how LSA is calculated. Now that I understand intake/exhaust Lobe Center design provides the "average" for the LSA, I need to some more thoughts/feedback. Given that my 360 combo has the stock compression height .060 forged pistons (= lower compression), would I want a low degree intake lobe center (106/107?) and a higher exhaust lobe center (112/114) to build more initial cylinder pressure. Example, I see these 2 Oregon Cam regrinds that utilize these different LCs:
1369: 218/224 (.050), LC: 106 (Intake), 114 (Exhaust), Lift (1.5) .462(I)/.470(E)
1176: 230/236 (.050), LC: 106 (Intake), 114 (Exhaust), Lift (1.5) .488(I)/.491(E)
I'm leaning towards the 1176 for my combination: Duster, 360 - 340 X-heads, single plane, single plane intake, 750 DP, 3k stall, 727, 4.11 gears (8 3/4). I've always been of the opinion; I'd like a little more cam than not enough.
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I think it goes like this.
LSA = (106+114)/2 = 110

I would use the 1176 cam with your combo. You could probably get it ground with a different LSA. 110 is pretty typical.
 
cookietruck said:
I think it goes like this.
LSA = (106+114)/2 = 110

I would use the 1176 cam with your combo. You could probably get it ground with a different LSA. 110 is pretty typical.
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Oregon cam said they could ground to a different LSA, but the LC (Intake or exhaust) will need to change to affect the LSA. My question involves building the highest initial cylinder pressure, so should I change the existing LCs (and consequently the LSA) or will that cam, as ground, build high initial cylinder pressure with the existing LCs?
 
middleagecrisis said:
Oregon cam said they could ground to a different LSA, but the LC (Intake or exhaust) will need to change to affect the LSA. My question involves building the highest initial cylinder pressure, so should I change the existing LCs (and consequently the LSA) or will that cam, as ground, build high initial cylinder pressure with the existing LCs?
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I think it’s mostly dependent on intake valve closing event.
I just did a dynamic compression calculator for a 360 since those numbers were fresh in my head.
Closing the intake valve 4* earlier builds an extra 5psi in cranking pressure.
I think if you spread the lsa then the recommended icl for the cam moves back a bit most of the time.
 
crackedback said:
Using the 1176, what is the narrowest LSA he can grind on your core?
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That would be a determining factor, wouldn’t it? I have two possible options, one a hydraulic purple cam I suspect it’s the.474/280, but I can’t find a part number on it. The other is a Mopar solid lifter cam with a lot of lift/duration and a 112 LSA.
 
The 474/280 cam seems to be on a 110.
I just had bullet regrind a cam. They said they could go one degree either way. I had a 110 and moved it to 111.

You prob want to go to 109 or maybe even get to 108. Prob depends on how much of the base circle he is comfortable with grinding…
 
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