------------------
1970 coupe restored with the help of my dad. 306 with 600 holley, Weiand Stealth intake, headers, Comp cam, harland sharp roller rockers, kb pistons, 11:1 compression ratio, pertonix ignitor 2 with matched coil, lakewood bellhousing, 4-speed toploader, and 2.79 open 8" rear. Soon to be 9" 3.50 trac-lok
1986 f-150, 5.0, factory towing package with original c-6 trans

I might want to run my girly cam through there just for laughs to see how much power I'm not making.
Thanks in advance.

I'm running that grind in my stroker now. 110* lsa, much tighter than the Crane's 114* if you're interested in overlap (cylinder bleed-off). In my deal, it starts comming on real hard around 3k... I shift at 7k and it isn't even starting to run out of steam

It will need more gear than you're running now.

Definetely not a daily driver, but yes, it is plenty streetable especially with a four speed. It will not make enough manifold vacuum for power assisted brakes (12-14" at best) so plan on either a canister or pump if you're running a booster

------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9"

quote:

---

Originally posted by V8 Thumper:
282S gets my vote

I'm running that grind in my stroker now. 110* lsa, much tighter than the Crane's 114* if you're interested in overlap (cylinder bleed-off). In my deal, it starts comming on real hard around 3k... I shift at 7k and it isn't even starting to run out of steam

It [b]will need more gear than you're running now.

Definetely not a daily driver, but yes, it is plenty streetable especially with a four speed. It will not make enough manifold vacuum for power assisted brakes (12-14" at best) so plan on either a canister or pump if you're running a booster

[/B]

---

And, definitely not daily driver, but plenty streetable must mean...slow around town until you put the pedal to the metal?

That's fine with me!

Whipping up on stoplight sprinters 100 ft. after the light turns green is more impressive when the other car realizes they don't have JACK on ya.
But then again, I don't drive like that on the street.

But, back to basics...I keep hearing conflicting data on this LSA thing?
When it makes sense to me, it doesn't make sense to someone else.
Where are these engine guru guys when the going gets rough?

Wide LSA...intake opens early, closes early, while exhaust opens late, closes late, allowing some pressure to be bled off because of the slower event?

Tight LSA...intake opens late, closes late, while exhaust is starting to open which creates a vacuum that scavenges the exhaust better, but also contaminates the intake charge, (smelly fumes) but also traps more pressure in the cylinder for compression, making a lower compression engine have more power?

C'mon guys, I get the concept, but what're the real facts?

Lobe Separation Angle.

The number of degrees between the intake and exhaust centerlines establishes what is called the LSA.
As an example, many Crane street cams are built using a 112 LSA. This means there are 112 cam degrees between the intake and exhaust centerlines.
This can be determined from a cam card by adding the intake and exhaust centerlines together, then dividing by 2.
So, if you add a 111 degree exhaust, and a 113 degree intake lobe centerline, then divide by 2, you get a 112 degree LSA.

Keep in mind that the lobe centerline number might also be the same number as the LSA, but they are completely 2 DIFFERENT functions.

Valve overlap is a function of both duration, and LSA. If LSA remains the same, but duration increases, the amount of overlap also increases.

Overlap is the time in crankshaft degrees when the exhaust and intake valves are both open.

Overlap helps improve engine performance by starting the INTAKE cycle before the EXHAUST closes.
As overlap increases, this tends to make the idle quality more erratic, or lumpy, while improving mid-range and top-end power.
But even slight changes in overlap and intake opening and closing points can make a BIG difference in performance.

My questions answered, but somehow, I knew that all along, I was just trying to converse with others on the subject.

So apparently, it's hit or miss.
Nobody can tell you what's the best for your application...you have to spend a little time and money and mistakes to find out for yourself.

In a nutshell.

quote:

---

Originally posted by itlbrnmoff:
[QUOTE]
Wide LSA...intake opens early, closes early, while exhaust opens late, closes late, allowing some pressure to be bled off because of the slower event?

Tight LSA...intake opens late, closes late, while exhaust is starting to open which creates a vacuum that scavenges the exhaust better, but also contaminates the intake charge, (smelly fumes) but also traps more pressure in the cylinder for compression, making a lower compression engine have more power?

---

Well, yes and no. Although a direct function and product of duration, a tighter lsa will have both valves open for 'x' degrees of the compression stroke, pumping at least ~some~ of the charge out the exhaust while lowering the compression pressure.

One reason rollers can be so much more aggressive than flat tappets. The ramp angle and speed is so great, the valves don't have to open as soon and can shut earlier while still out-flowing a comparably speced flat tappet. A roller can yank the valve open very quickly and slam it shut, thus increasing manifold vacuum and increasing cylinder pressure as the overlap is (or can be) less. Geometry and physics

------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9"

I think the magazine info I typed in explained it better.

Where are the cam experts this week?

But doesn't the compression stroke take place when both the intake and exhaust lobes are on the base circle?

Which would explain that when the 2 lobes are further separated (less overlap) might cause some pressure bleed off because the valves might start to open sooner again as the piston is approaching TDC on the compression stroke?

I guess what gets my mind in a clusterf*** is that when I'm trying to visualize the opening and closing events, I'm not sure where the piston is in relation to the valve events.

Do they still make those see through visible V8 models?

https://mustangsandmore.com/ubb/Forum12/HTML/006666.html
------------------
'83 Mustang GT T/tops 306, 5-speed, 3.45 trac-loc, 650 dbl. pmpr. RPM intake, headers, 2 1/2" exhaust, 2 chamber Flowmasters = LOUD....
'88 Lincoln Mark VII LSC 5.0 HO, AOD, leather, A/C, 3.27 trac-loc...

------------------
1970 coupe restored with the help of my dad. 306 with 600 holley, Weiand Stealth intake, headers, Comp cam, harland sharp roller rockers, kb pistons, 10.3:1 compression ratio, pertonix ignitor 2 with matched coil, lakewood bellhousing, 4-speed toploader, and 2.79 open 8" rear. Soon to be 9" 3.50 trac-lok
1986 f-150, 5.0, factory towing package with original c-6 trans

I looked for that engine program and couldn't find it. Maybe I didn't try hard enough.

------------------
SCOOP

oddly obsessed with big scoops on little Mustangs

2.26 60'S
14.9 @ 90.86MPH

65 coupe,351w,C4,Big Boss 429 hood scoop,8" 3.40 TracLoc.

My Pics

As a point of reference I ran essentially the same engine that you have ? a 306 with GT-40 heads (same as early 351W heads), 10:1 compression, 600 Holley double-pumper, RPM intake and the following cam: 230/235 duration @ .050, .510/.515 lift with a 107 LSA. It was a great cam with a choppy idle that pulled to 6200 RPM?s. I think the 282S would be similar. The Crane cam seems a bit large on the duration and the LSA being 114 would seem to raise the dynamic compression enough to make detonation a possibility (maybe).

quote:

---

Originally posted by '69Stang:
I?m no cam expert but I do know that a narrower LSA will cause more overlap, leading to more cylinder ?bleed-off?. The narrower the LSA the less time the separate valve events have between each other to complete their portion of the internal combustion cycle.

---

But I've always thought it bleeds off pressure too.

Where is our multi-world record holder?

Alex...HELLLLLPPPP!!

I have no credibility here, and any future chances are going out the window.

Increasing lobe seperation
1. widens powerband
2. makes the idle smoother
3. takes away from the midrange
4. produces less maximum power

Racers usually use tight lobe seperations. The only exceptions are Pro-Stock, where 500+ ci are revved to the moon with cams so HUGE, tight LSA's produce too much overlap, and nitrous/blower/turbo applications where overlap sends all that extra fuel mixture out the tailpipe!

Tight lobe seperations increase overlap and can help increase velocity in overly huge intake ports (4bbl 351C). This will pump up the midrange, and make the engine feel less "lazy". Some 351C drag race cams have lobe seperations as low as 102-104 degrees. Automatics generally need a tighter lobe seperation for extra midrange.

Small engines with big ports LOVE tight lobe seperations, large engines with small ports work better with wider angles between the lobes.

A GOOD, free flowing exhaust is required on engines with cams having tight lobe seperations. Without a good exhaust, the exhaust just doesn't flow out, creating a vacuum to pull the intake charge in like it should. The exhaust just backs up into the cylinder and makes the car run like crap. Extreme cases will even have the exhaust back up into the intake, which will turn the inside of the carb black with soot.

Tight lobe seperations can also be used on engines with restricted intakes and carbs. When used correctly, that extra overlap can help draw extra fuel/air mixture through the restricted intake ports and carbs.

A tighter lobe seperation also allows you to use a slightly larger cam in a lower rpm range. If you want maximum valve timing without revving the engine to the moon, a tighter lobe seperation can make it happen.

Here's an image that will help explain how WIDENING the lobe seperation DECREASES cranking cylinder pressure. You can see how spreading the lobes further apart puts the intake event further into the compression stoke. This causes the valve to be open longer into the compression stroke... bleeding off cylinder pressure.

Just be sure to use an extremely free flowing exhaust with extra tight lobe seperation angles. Their scavenging effect from their extra overlap NEEDS some free flowing tubes, or the exhaust will just get backed up into the cylinders... Really bad exhaust systems will actually make the carburetor get all black with carbon. Open er' up, and let er' fly! I really like the dual 3" woofers that occupy the underside of my car.

Good Luck!

------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220

quote:

---

Originally posted by Buster:
I think I agree with everyone in this thread.

---

Here are my results...
306 w/ E7TE heads...although I couldn't include the 1.90/1.60 valves...
RPM intake...
650 dbl. pmpr.
1 1/2" primary, 3" coll. full-length headers.
2 1/2" free-flowing full exhaust....
Lunati 218 @ 0.50 .488 int./.488 exh. lift 110 LSA....

Peak Tq = 327 ft.lbs. @ 4000 rpm
Peak HP = 296 @ 5000 rpm
Peak VE = 97.5 @ 4500 & 5000 rpm

same as above, except open headers...

Peak Tq = 332 @ 4000 rpm
Peak HP = 302 @ 5000 rpm
Peak VE = 98.7 @ 5000 rpm

Now, I know there are alot of variables, and this program does "not" guarantee accuracy, but that's darn close to an ideal street engine I think.

And it made 215 HP (the factory rating) from 2500 rpm increasing to the 296 HP @ 5000 rpm peak.
(Actually, 175 HP for an '83 carbed & flat-tappet cam.)

A full report stated that more TQ & HP could be gained by increasing "overlap" (tighter LSA) and more duration @ 0.50....but for 9:1 compression, I'm about right where I should be.

Not bad for a 1st rebuild.

------------------
'83 Mustang GT T/tops 306, 5-speed, 3.45 trac-loc, 650 dbl. pmpr. RPM intake, headers, 2 1/2" exhaust, 2 chamber Flowmasters = LOUD....
'88 Lincoln Mark VII LSC 5.0 HO, AOD, leather, A/C, 3.27 trac-loc...

[This message has been edited by itlbrnmoff (edited 02-09-2004).]

------------------
mike r
racing is real
everything else is just a game.
81 capri-7.47 @90mph 1/8
1.54 60 ft.

quote:

---

Originally posted by capri man:
dang, are you guys trying to gain .002 sec to break a world record, or what?? just call the cam company of your choice and put in what they reccomend!

---

Sure Mike make it sound easy
I like me they are just wanting to get all the they can for the money.

I was talking to a guy that has an exhaust shop here in town. He also drag races, he told me that a good 3" system with an x pipe might be worth a .2 or less depending on the motor. But he doesn't think it's worth extra money and sound level. He said a good 2.5" system with no H or X pipe and some good NON flowmasters will flow better then most street cars will ever use.

------------------
SCOOP

oddly obsessed with big scoops on little Mustangs

2.26 60'S
14.9 @ 90.86MPH

65 coupe,351w,C4,Big Boss 429 hood scoop,8" 3.40 TracLoc.

My Pics

quote:

---

Originally posted by capri man:
dang, are you guys trying to gain .002 sec to break a world record, or what?? just call the cam company of your choice and put in what they reccomend!

---

But also, I got a chance to see where I might stand as far as power with my set-up.
Now I know my engine is more suited to street duty and maybe some occasional strip use for fun.

You guys might want to download that engine analyzer just for fun, it's fun to use also.

quote:

---

Originally posted by BLstangin:
it sounds like I need the wider lsa to bleed off cranking pressure and make it run on pump gas and still drive very well on the street.

---

Keep in mind, the extra duration on the intake lobe will also bleed off cylinder pressure. You might not need and 'extra wide' lobe seperation angle.

Good Luck!

quote:

---

Originally posted by BLstangin:
So Mike are you saying that maybe this crane cam would be a good one, but maybe I could have it custom ground on a tighter lsa, like a 112, or a 110, or is that not going to help me any? It has 5 degrees of advance ground into it.

---

i hope you were talking to the other mike because yall left me about 2 days ago!!
heck, i can hardly remember the speed shop's phone # much less all these other big numbers!! good luck guys.

------------------
mike r
racing is real
everything else is just a game.
81 capri-7.47 @90mph 1/8
1.54 60 ft.

quote:

---

Originally posted by BLstangin:
Ya, that's the program I was talking about. Thanks for the help guys. I think I am going with the crane cam. itlbrnmoff you can put my combo in the program if you want and compare the 282s and the crane. You can then see the difference and give me your opinion based on the program. I have given the specs thoughout this post. n20 Mike thinks for the help, it sounds like I need the wider lsa to bleed off cranking pressure and make it run on pump gas and still drive very well on the street. Thanks guys, you have made cams much more understandable for me.

---

First of all, both the Crane cam and the Comp 282s seemed to have about the same torque powerband that started at 2500 rpm and peaked at 5000 rpm.

First the Crane.
TQ = 211 ft.lbs. @ 2500, peaking at 306 ft.lbs. @ 5000 rpm.
HP = 325 @ 6000 rpm.
estimated idle vac. @ 10.7 hg.
spark was retarded to 33* @ 3000 rpm to avoid detonation, but was OK at every other rpm.

Comp 282s.
TQ = 225 ft.lbs. @ 2500, peaking at 312 ft.lbs. @ 5000 rpm.
HP = 324 @ 6000 rpm.
estimated idle vac. 10.4 hg.
Here's the kicker.
spark was retarded at ALL points between 2500 rpm & 4500 rpm to avoid detonation.

So, confirming the fact that "overlap" DOES increase cylinder pressure enough to cause detonation, but overlap can be REDUCED when it's ground on a "tight LSA" by reducing the DURATION of the cam.
Overlap will INCREASE with a tight LSA, and a large duration.

So, you could either go with the Crane for it's "wide LSA" and large duration, or consider going with the Comp 282s, but having your distributor advance set to be all in by 2500 rpm max so it doesn't reach the point of detonation.

I forgot to mention though about the air/fuel ratio data.
Assuming that the analyzer is using factory holley jetting figures.
The Crane cam was showing a much better A/F ratio throughout the whole rpm range than the Comp cam was.
The detonation that the Comp cam was producing could be remedied by going up on the jets because a cam with overlap will need higher jetting.
The fuel being sucked into the exhaust from the open intake valve will cause a leaner A/F ratio.
Also proving the point that "fuel mileage" ain't gonna happen with a high overlap cam.
More HP = more $$$$$$

------------------
'83 Mustang GT T/tops 306, 5-speed, 3.45 trac-loc, 650 dbl. pmpr. RPM intake, headers, 2 1/2" exhaust, 2 chamber Flowmasters = LOUD....
'88 Lincoln Mark VII LSC 5.0 HO, AOD, leather, A/C, 3.27 trac-loc...

1 5/8"x 34" length primary headers...
2.5" typical aftermarket 500 cfm exhaust...
Then, the results were different than I posted earlier.

First the Crane.
238/248 @ 0.50 512/533 lift 114* LSA installed Straight up.
TQ = 194 ft.lbs. @ 2500 rpm, peaking at 300 @ 5000 rpm.
HP = 329 @ 6500 rpm.
No spark retard at all, 39* total to 6500 rpm.
Cranking compression = 144 psi.

Comp 282s.
236/236 @ 0.50 528/528 lift 110* LSA, installed straight up.
TQ = 206 ft.lbs. @ 2500 rpm, peaking at 309 @ 5000 rpm.
HP = 330 @ 6500 rpm.
Spark retard to 36* at 4500 rpm only.
Cranking compression = 160 psi.

OK...In light of the new results, it seems the Comp 282s is actually the best choice between the 2 cams.

The comp 282s has more TQ across the board, because the Crane loses too much cranking compression.
It would seem that you could set up your distributor for 36* total timing advance and not have issues with detonation...nothing that a little test and tune couldn't fix.

The Crane cam is just too lazy, and loses 12 ft.lbs. of TQ from the get go.
Comp 282s wins this one.

You did a pretty good job narrowing it all down to those 2 cam choices...if it were my engine, I'd go with the Comp 282s...
More TQ than Crane, and keeps pulling HP all the way to 6500.
It's a no-brainer.

BlkFord was just free-wheeling his engine to 7k. With a load, I'd say his 331 will run best shifted around 6500 rpm.

You domed pistons have you limited with cam selection. Install a set of flat tops, and you can use a 270S, which will probably match up to the rest of the engine better.

The Crane cam will want to rpm even higher, plus, it will be soft in the midrange.

Good Luck!

quote:

---

Originally posted by BLstangin:
Thanks for all the help. The thing that gets me is that Todd runs it and he has to spin a motor with 27 more cubic inches to 7,000 rpm to use it all and I am afraid it will be a classic case of overcammed. Alex would you please be so kind as to chime in and give me your opinion. It would mean a bunch to me to hear from someone with the expertice you have. Thanks to everyone for your help. After the last numbers posted I am begining to wonder which one is better since my friend who should be using the same program has a few more horse and a much better torque curve out of the crane cam. Also what did the torque curve look like on your program, fairly flat, or was it peaky?

---

The Crane has too much duration, and if you want to spin it to 7500 rpm to get the full HP, that's fine, but the TQ curve still gives out at 5000 rpm.

I'd rather have useable TQ in a useable rpm range and still get HP up to 6500 rpm...that would be the Comp cam.

Either way, time is money, that'll be $5.00 please.

BTW, I didn't know you have domed pistons either?

quote:

---

Originally posted by BLstangin:
Thanks for the links. I don't know if they helped or made me more confused. O.k. so lets say my 306 with 10.3:1 compression ratio 2.5" mandrel bent exhaust, 3.50 gears, and a 4-speed with ported D0OE-C windsor heads, and a stealth intake with a 650 double pumper is going to like a wider lsa, and more duration, making the crane the better choice. The 2 cams are very close according to the computer program, which buy the way my friend found at a mustang website that had it as a free download. I think it was mustangshop.com. Am I correct or way off base here? Thanks for the continued help. Brandon.
One more thing, wider lsa= lower cranking compression= less chance of detonation and pinging, correct?

---

quote:

---

Originally posted by Fastymz:
Did you call Alex ?

---