[Cliff R]

Good post Paul.

One item not mentions when it comes to LSA is CID and stroke. Piston speed and swept volume play a role here, and so does rod length to a lesser degree.

Most of my comments on cam choices are directed a the long stroke engines and pump gas street engine builds.

For race stuff we try to get all the compression in them we can and go to HUGE cams on tight LSA's. Race engines use high octane fuel and operate in a much narrower rpm range than a street engine, so most are fine with 265-285 @ .050" cams on tight 108-110LSA's.

For a street 455, you are trying to take a somewhat poorly designed engine and improve it's basic operating characteristics. The 455 engine has a long stroke, long rod, and relatively small runner cylinder heads. It's not going to be a strong running high rpm engine by design, and is going to try to throw all it's power at you right off idle, with power ending early in the rpm range.

What happens with small cams and tight LSA's, is that they further enhance the good qualities of the 455, and pull power down it the rpm range and make more of it. When peak VE happens early, you get a really high torque number early and high cylinder pressure to go with it.

This is why we have had quite a few troubled 455's in here to tune that had difficulties managing pump fuel, even though the SCR was at or even under 9.5 to 1. The very worst ones used cams with short seat timing events (Comp XE lobes), and the even better XR276HR cam, all of which produce peak power just past 3000rpm's and a LOT of it. Problem is, the engine mimics one with really high static compression, and they will NOT manage pump fuel with "normal" timing/fuel curves in them.

The XR276HR cam is the worst of the bunch, since it's roller lobes provide excellent cylinder filling without a lot of off seat timing or overlap. The last one I had in here to tune would ping at light, heavy and full throttle, and would take no amount of vacuum advance at all from the distributor. Anything beyond 26 degrees total timing and it POUNDED like sledgehammers in the mid-range. No amount of fuel dumped on it made any difference.

To prove the "too small of a cam" deal I installed HS 1.65 rockers on it, and was immediately rewarded with being about to put a few more degrees power in it without pinging, and I added 8 degrees from the vacuum unit as well. It helped some, but the engine was still octane sensitive and WAY down on power from what I thought it should have been.

The dyno charts put up earlier in this thread show why, the cam is simply too small, too good at cylinder filling, and LSA too tight for the 455 engine, at least one with a little compression in it.

Paul has pointed out that some folks don't care about big power from these engine builds, and will NEVER race them or rev past 5000rpms, so there is a customer base that would be fine with a small cam in a 455 build as long as it's user friendly. Most of the folks that come to me for engine work or tuning are wanting it ALL. Big power, decent idle, good street manners, no running hot/overheating/detonating on pump gas and run like a race car if/when they decide to go to the track. A good percentage of them also prefer or lean towards "stock appearing", so don't want or care to have a lot of aftermarket parts in plain view.

These facts have led us to test and use parts to extract optimum power from pump gas street engine builds, without a lot of bling, or crappy idle qualities and poor street manners. I've known for many years that 455 engines do NOT like small cams in them, especially when you start pumping up the compression in them and increasing head flow.

Anyone reading this should take a close look at the dyno charts, and read about how they came to be. NONE of that work was done here, it was done by a shop that does a lot of high performance engine builds and has their own dyno. They found out, that simply by choosing the wrong cam, they were leaving nearly 90hp on the table and built a relatively "low" compression engine that would NOT manage currently available pump fuel.

At least we have some direct testing to show why I've been dubbed the "Comp XE cam basher" for quite a few years now. My own testing and testimonials don't seem to have been sufficient, so I was glad to see a professional engine builder get some hard data on one of these engines to show what I've been talking about......Cliff

[gtofreek]

Originally Posted by 72LuxuryLeMansLa.

If dynamic compression calculators have no real place in engine building how do you figure out how much pressure will result from a cam? Do you use static compression ratio calculators? Static in my opinion doesn't help since you get no compression until the Intake Valve closes........

Jim Hand and David Vizard are two engine builders that I believe are knowledgeable and considered expert engine builders by most. They seem to think Dynamic Compression ratios are to be considered........

http://pontiacstreetperformance.com/...mpression.html
http://www.hotrod.com/events/coverag...power-squeeze/

Karl, if you re-read my example, you will see why dynamic calculators don't accurately determine cylinder pressure. You can even have two cam lobes that close the valve at exactly the same point, but if one lobe does a better job at filling the cylinder, that lobe will make more cylinder pressure, thereby, raising the dynamic compression, even though the calculator shows them being the same. Most people don't think about this when they think about dynamic compression. Hell, I never really thought about it like this either, until a very wise man[Harold Brookshire] explained this to me. Then, I thought about it, and realized he's exactly right.

This is why cam companies always recommend a static compression ratio for cam lobes. Cams should be picked based off of static compression, not what they MIGHT produce dynamically. Harold designed cam lobes specifically for better cylinder filling. He has eliminated dead spots on the lobe where valve acceleration remains constant, and made those spots keep accelerating at greater speeds until near max lift. This helps initiate, and create more velocity in the intake runner[really important with large intake runners], for better cylinder filling. His lobes fill the cylinder better than most, and as a result, create more dynamic compression, and more cylinder pressure, which equates to more power. As far as detonation is concerned, whenever we use one of his cams in an engine with the appropriate compression ratio for it, and install it where he wants it, we don't have detonation issues with them.

I had an Erson high flow III cam[240° @ .050/316° advertised] in my 428, and my 400. It was a pinging SOB in the 428[high compression]. It was so bad it would ping in neutral, just stepping on the gas. That cam went into my 10:1 400 where it pinged pretty bad also. I advanced it 4°, and it quit pinging all together. Why did it quit pinging even though I advanced it, and theoretically produced more dynamic compression? Because it changed the intake and exhaust valve positions at TDC. In the advanced position, it had the intake valve open more at TDC, and the exhaust valve open less at TDC. This, in turn, lets the piston suck more on the intake side, than the exhaust side, thus sucking in less exhaust gasses to heat things up. So the pinging went away. Also, that cam was a dog under 3000 RPM when installed straight up, but when i advanced it, it was a screamin' demon! Had much more power under 3000 rpm than before. And the best part was, NO PINGING on 87 octane! Before, it would ping on 91 with octane booster in it. Matter of fact, octane booster never really did anything for that 428 with this cam installed straight up. Never tried advancing that cam when it was in my 428.

[71 T/A]

Very good post, Cliff, and what you're saying is true but the OF HR cam is a much bigger cam than the HR276.

[Skip Fix]

Most simulators also have the programmer bias in when comparing HFT to SFT to solid roller as far as HP gains.

[Steve C.]

Speaking of David Vizard, and a fwiw for conversation here...

Many years ago David Vizard developed a comprehensive computer program that offered precise cam selection. It was not duration-driven as you might expect but was overlap-driven. The event timing of the cam, dictated by the duration of the intake and exhaust, together with the Lobe Separation and the advance/retard position in the engine. Once the overlap to suit a given application is decided, everything falls in place.

Now one thing to note is that more often than not this program suggested a narrow lobe separation rather than wide.

Example, at the time I used the program for interest on a previous 4.210 stroke 462cid combination. In part, the computer input was based on a street/strip application with 70-90 degrees overlap. Peak power at 5500 rpm. Cam type was for a solid roller. And a low 9.95 static compression ratio.

The results suggested 286 degrees duration at .020", 253 degrees duration at .050" lift and a 105 lobe separation. With my engine builder we ended up ordering a custom single pattern XE solid roller cam with 254 degree at .050" and we decided to have it ground with a 108 lobe separation. I also contacted Chris Mays at Comp Cams and John Partridge at Bullet Racing cams prior to ordering the cam, after going over my total combination and goals both suggested the same 108 lobe separation. The engine on the dyno made peak power at 5800 rpm and 580 hp with a Performer RPM intake.

Also this article below by David Vizard might be of interest, take note of his thoughts regarding a narrow lobe separation.....

Cam Science
Resolving the Mysteries of Lobe Center Angles

Read more: http://www.hotrod.com/how-to/engine/...h/#ixzz3hU8HPX


.

[Cliff R]

"This is why cam companies always recommend a static compression ratio for cam lobes. Cams should be picked based off of static compression, not what they MIGHT produce dynamically."

Very true, except cam companies leave out the most important piece of the puzzle, the CID of the engine the cam is going to end up in.

At the bottom of their notes they will say that it fits 326 thru 455 Pontiac engines, and maybe something like 9.5 or "raised compression" recommended. Sounds great except for the fact that a cam that is completely happy in a 350cid engine at 9.5 to 1 is more often that not going to be a very poor choice for a 455 engine at 9.5 to 1.....FWIW.....Cliff

[Steve C.]

And when they state a specific or suggested static compression ratio it doesn't take into consideration cylinder head material, alum or iron. Same with many of the computer simulations that have static compression as part of their input, Performance Trends Engine Analyzer is one example.

I believe Crower does in some cases have categories for different engine sizes for some of their cams.

.

[67GTO4SPEED]

Let me preface this post by saying I appreciate all the posts on my comment about the LS cams, and respect you guy's opinions/experiences. I'm here to learn from guys like you. I have a few questions to clarify some of the posts, so please take these questions as me trying to learn more as opposed to thinking I'm being argumentative or trying to "one up" you. There's plenty of that here in the Race section!

Originally Posted by hurryinhoosier62

It's a simple answer: fuel injected engines need LSAs of 112-116 degrees.

This is true, but I know a couple of guys running LS engines in old cars with carbs, and these wide LSA cams are making stupid power. There's a guy here locally with a carb'd 421 cube LS in '69 Nova with a cam very similar to one below and he's running very low 11's on motor. The engine doesn't act that rowdy, and it is actually pretty dang streetable, which I think is the point of the thread. It runs so well that it has made me wonder how it would work having some of those lobes put on a custom grind Pontiac camshaft.

Are you saying that you think this style cam is a compromise and is potentially leaving power on the table being that has to have a wide LSA being that it is an EFI cam?

Originally Posted by gtofreek

Wide lobe seps are not considered old school. There are engine combos that need them, or run better on them. Long stroke engines can benefit from them to keep the engine in a wide power band to pull the car. Engines that need to make power at 9000-10,000 RPM's NEED wide lobe seps[sometimes as wide as 119°-120°], and big duration cams. Narrow lobe seps run out of steam too soon to make power up there.

To guys like you that know what they are talking about - no, they aren't considered old school technology. However, to a lot of average Joe car guys out there, they are. They've been told by magazines, the guy at their local motor machine shop, and lots of other places that you CAN'T run more that 9.5 : 1 in street, and the best cam out there is a Comp XE, and before that a Comp High Energy or Magnum.

About 20 years ago I had a #461 double hump (62cc) headed .060" over 350 SBC in a '68 Camaro. I bought the car from an older guy that built it pretty much as old school as you can. It had forged flat-tops with the little small valve reliefs, "pink" rods, steel crank. The heads were cut about .030" and were bowl ported, it has a high rise dual plane factory L-79 intake with a 650 DP and a set of Hooker Headers. It had the infamous "151" L-79 cam with a 1.6 roller tips and Z/28 springs. It was a 4 speed car, and that damn thing ran like a demon! I never got a completely clean pass back then because I never put it on slicks, but I managed some mid 12's at 111 - 113 MPH (which says it had more) while spinning the Mickey Thompson Indy Profiles that were on it. The car idled very mildly, the brakes worked great, and it never detonated. It was a very fun car in every way.

After having it a while, everybody and his brother told me how much power I could gain by putting a Comp 270H Magnum in it. I called Comp and told them my combo and it was said to be the biggest Magnum cam that you could run with power brakes and stock converter and would work well with my combination. I pulled the trigger and bought the cam, lifters, and springs and put them in one weekend. After we fired it up and broke in the cam, we were like OMG!!! This things sounds like as race car! I drove it around on the street, and it spun like crazy (like it did with L-79 cam), but I could just tell that it was going to be faster. It sounded awesome, so it had to, right? A few weeks later we took it to the track and the car slowed down. This bigger, better, modern cam would not rev anything like the L-79 did and just wasn't stronger really in any RPM range. Ok - I had to have done something wrong. I re-checked everything, but everything was right. I had a few guys that were more experienced than me look at it - re-checked the timing, re-set the valves, and everything was right. We played with jets, and could not get it run like it did before. It still ran OK, and sounded great, but the brakes weren't as good and it ran a touch hotter. I was driving it on a real hot southern summer day and I thought a I heard valve rattling when I wound it up in 1st leaving a stop sign. I talked to some people and told them my combo and we determined with the cut 62cc heads, small valve relief flattops,and being .060" over (360 cubes) that I was probably pushing a touch over 10 : 1 CR. I bought some Sunoco 110 and we cut it half and half with pump gas. I took it back to the track and sure enough it picked up about a tenth in the 1/4. The mid-range was stronger than it had ever been before, but it still never revved like it did with L-79 cam and I had shift at a lower RPM. It had been obviously been detonating, but I never heard it until that hot summer day. I ended up dropping the timing a little bit, and the problems went away, but it never ran like it did with before the cam change unless I bumped up the octane.

I never went back and dropped the CR to be more friendly with the Magnum cam, but I can't see where it would have been any faster than it was with the race fuel blend. Even if it had been a tenth or two faster, it wasn't as fun to drive and wasn't as streetable. That old 30+ year old cam (back then - almost 50 years old now! ) was much like those RAIV's, and just plain worked! It idled well, had plenty of vacuum, and truthfully, I wouldn't hesitate to a build a L-79 cammed SBC today as long as it had enough CR to take advantage of it.

Originally Posted by gtofreek

We all know that wider lobe seps make less peak power than narrower lobe seps, but in a broader RPM range. More average power. Certain lobe designs, by nature, benefit from wide lobe seps, while other lobes benefit from tighter lobe seps. If you have a lobe design that when ground on a 110° LSA, has a power band as broad as another lobe design ground on a 112° or 114° LSA, why not take advantage of the extra power if your not running the cam out of it's power band in the first place?

Isn't more average power what you need in a TRUE street car? (Meaning a car that is built for the street that might go to the track sometimes, as opposed to a car that is built for low ET's but called a street car). The reason I ask is that I've been in street cars and actually built a few many years ago with Comp XE cams that ran pretty good, but had a narrow range of power. These cars ran pretty good at the track too, but they required low gears (4.10's) and pretty loose converters to run fast. That's fine for a street/strip car, but nothing I'd want to drive a lot. Power over a broader range is seems like the cure to that problem.

That said, I am not too close minded to listen to suggestions, recommendations, and other people's experiences with tighter LSA cams that make great power and are very streetable. What tighter LSA camshafts/lobe designs out there make power over with the same broad range as a cam with a wider LSA and is as equally streetable (good vacuum, low idle, no need for a big converter)?

Originally Posted by gtofreek

The factory's use wide lobe seps because they can run more duration and still have mild manners. The bigger cams with wider lobe seps will still make good vacuum, and have better driveability than if they ground them on tight lobe seps. The factories are looking for smooth idles, and good driveability, NOT mean sounding hotrods. They also need them to pass strict emissions laws. Something that is not going to happen with 220° @ .050", ground on a 108° LSA. I understand why the OEM did what they did. I don't argue with it. I just don't think it's always the best way to go for everything.

Again, all of the above sounds exactly like what I (and a lot of other people) want out of their car. To put it bluntly, many of us want the cake and to eat it too! I want the car to be very streetable but I'm not satisfied with being a low 13, high 12 second car. I want the car to be fast but to act like it's not. That's what these these longer duration cams with wider LSA's in big inch engines with a healthy compression ratio seem to offer. I couldn't honestly care less about it sounding like a hot rod or race car. I'd rather it sound like a car with a mild street cam that drops jaws when it goes around a so-called hot rod or down the track. This doesn't seem to be what you typically get with a tighter LSA cam, correct?


If I understand you right, you are saying that a well designed cam with a tighter lobe separation can potentially make more power as long you are more interested in ET than streetability, meaning that you like most things, you have to compromise some power to have good street manners.

[Skip Fix]

That said, I am not too close minded to listen to suggestions, recommendations, and other people's experiences with tighter LSA cams that make great power and are very streetable. What tighter LSA camshafts/lobe designs out there make power over with the same broad range as a cam with a wider LSA and is as equally streetable (good vacuum, low idle, no need for a big converter)?

My friend's RAIV headed 428 in a 70 TA stick car. Swapped an UD 288/296 on a 110 from Butler for an 068. Thought it felt slower than the 068 until he took it to the track and it went .2-3 seconds faster. Idled just barely more lope.

Lee Atkinson had same cam on a 108 in his first gen Bird got in the 11s with it. I had one on a 108 in a 455 in my TA that ran PB and A/C and no Rhoades lifters. With a road race suspension the car open headers ran 12.30s@118.

[67GTO4SPEED]

Originally Posted by Skip Fix

Lee Atkinson had same cam on a 108 in his first gen Bird got in the 11s with it. I had one on a 108 in a 455 in my TA that ran PB and A/C and no Rhoades lifters. With a road race suspension the car open headers ran 12.30s@118.

Those are strong numbers for sure. What heads/carb/intake/CR, etc. were you guys running with those cams?

[Steve C.]

Link to Lee's Pontiac....

http://www.pontiacstreetperformance....uild45500.html

I'm not positive but I believe Lee's best was 11.46 at 115.4 mph with a 1.53 60 ft.

He later changed to a UltraDyne solid flat tappet cam with 247 degrees duration ground with a 108 lobe separation. I think he ran 11.27 at 119.6 mph after the change. Streetability was similar as I recall.

Information posted by Lee previously....

I ran an UltraDyne 288/296 HFT for many years in my 455. It was on a 108, and my best performance came with shifting it around 5300.

I later replaced it with an UltraDyne 280/280 SFT, also on a 108. It ran best shifting at 5900.

The HFT had MUCH better power off the line, my converter flashed to 32-3300rpm, and I could get 1.53 60' times with 3.42 gears.

The SFT was softer off the line 1.59-.61, but ran 3mph and .2 quicker in the 1/4 mile.
__________________
'67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 with old UD 288/296 hydraulic cam] Feb '05 HPP Shootout article



.

[67GTO4SPEED]

Originally Posted by Steve C.

Link to Lee's Pontiac....

http://www.pontiacstreetperformance....uild45500.html

I'm not positive but I believe Lee's best was 11.46 at 115.4 mph with a 1.53 60 ft.

He later changed to a UltraDyne solid flat tappet cam with 247 degrees duration ground with a 108 lobe separation. I think he ran 11.27 at 119.6 mph after the change. Streetability was similar as I recall.

Information posted by Lee previously....

I ran an UltraDyne 288/296 HFT for many years in my 455. It was on a 108, and my best performance came with shifting it around 5300.

I later replaced it with an UltraDyne 280/280 SFT, also on a 108. It ran best shifting at 5900.

The HFT had MUCH better power off the line, my converter flashed to 32-3300rpm, and I could get 1.53 60' times with 3.42 gears.

The SFT was softer off the line 1.59-.61, but ran 3mph and .2 quicker in the 1/4 mile.
__________________
'67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 with old UD 288/296 hydraulic cam] Feb '05 HPP Shootout article



.

Thanks for that! That engine is very similar to my build, except I'm going to run a ported stock intake, a Cliff'd 800 cfm Q-jet off a 455 Buick, and ported RA manifolds to keep retain my Ram Air pan and to look stock.

[Steve C.]

Lee's car, Skip's car and my '70 TA go back awhile

20 years ago my car had a 412cid combination with race ported #16 d-port heads, Performer RPM intake and a Holley carb rated 926 cfm. Back then Harold at UltraDyne also suggested a cam with a 108 lobe separation, it had 251 degrees duration. It was heavier then, probably closer to 3800 lbs race weight. With that combo the best ET was 11.45 at 118 mph. It came from the factory with a TH400 trans and 3.73 gears.


.

[72LuxuryLeMansLa.]

Originally Posted by Steve C.

Lee's car, Skip's car and my '70 TA go back awhile

20 years ago my car had a 412cid combination with race ported #16 d-port heads, Performer RPM intake and a Holley carb rated 926 cfm. Back then Harold at UltraDyne also suggested a cam with a 108 lobe separation, it had 251 degrees duration. It was heavier then, probably closer to 3800 lbs race weight. With that combo the best ET was 11.45 at 118 mph. It came from the factory with a TH400 trans and 3.73 gears.


.

How was the idle quality on that bad boy? 412ci with 251 on a 108.............is that the advertised or .050" duration? Street use?

[77 TRASHCAN]

Originally Posted by Steve C.

Lee's car, Skip's car and my '70 TA go back awhile

20 years ago my car had a 412cid combination with race ported #16 d-port heads, Performer RPM intake and a Holley carb rated 926 cfm. Back then Harold at UltraDyne also suggested a cam with a 108 lobe separation, it had 251 degrees duration. It was heavier then, probably closer to 3800 lbs race weight. With that combo the best ET was 11.45 at 118 mph. It came from the factory with a TH400 trans and 3.73 gears.


.

Ha!
I remember that engine, talked to you a little @ Southern Nat's.

Karl, that would have to be @ .050

[Skip Fix]

There was one Southern Nats Lee and I were in the quarter finals -both using the 288/296-108- him with a 455 mine a 400 , Lee low 12s me mid 12s 109 3900lbs (Jim Hand was still in the 12s back then also). I lit the red bulb -Lee's wife at the time swore I did it to leave early as it was a typical 100 degree Southern Nats in Dallas! Never figured why the Dallas guys never did it more in the spring or fall. It was still a good event back then, good friends and good times-just HOT-try sitting in a black T top car in the staging lanes in Texas summers.

[gtofreek]

Let me make one thing perfectly clear. When I talk about narrower lobe sep cams in big engines, I am specifically talking about Harold cams. Not Comp XE or anyone else's tight LSA cams. Harold did many things differently to his lobes. Things NO ONE ELSE DID! These subtle little things created lobes that when ground on a 110LSA, gave the power band performance of a cam ground on a 112-114 LSA. Just look at some of the Voodoo lobes. They all have 4000-4200 RPM power bands.

Just look at these two cams.

Crower 60919. Duration at .050" = 231/240, 304/316 Adv., ground on a 112° LSA. Power band = 2000-4800 RPM.

Voodoo 10510704 = 233/241 @ .050", 276/284 Adv., ground on a 110° LSA. Power band = 2000-6000 RPM.

Here the Voodoo cam has a much broader power band, even though it's ground on a tighter LSA. This is a Harold cam at work right here. His cams cannot be compared to others, only his own. Like I said in another post. Comparing Voodoo lobes to XE lobes is like comparing ice cream to horse radish sauce! There is simply no comparison.

I firmly believe that when running another cam designed by someone other than Harold, you really need to go wider LSA with the smaller duration cams in order to have the broad power band. I NEVER disputed that. I only dispute it when people classify the Voodoo lobes with others like XE lobes, when they have no experience with Voodoo lobes. That's the problem. People condemning a cam simply because what they see on a cam card. The cam card does not show the entire lobe. Matter of fact, cam cards show very little about a cam lobe, and leave out the most important stuff. Duration @ .200", how much the valves are open at TDC, etc.

The Magnum cam you referenced had too narrow of a power band for what you were doing. That's why the factory cam worked better. Narrow lobe seps, in most cases are for engines that run in a narrow RPM range, like a circle track engine, for example.

Also, cam companies consider a 110° or higher LSA a wide LSA. Anything under 110° is considered narrow.

Originally Posted by 67GTO4SPEED

Let me preface this post by saying I appreciate all the posts on my comment about the LS cams, and respect you guy's opinions/experiences. I'm here to learn from guys like you. I have a few questions to clarify some of the posts, so please take these questions as me trying to learn more as opposed to thinking I'm being argumentative or trying to "one up" you. There's plenty of that here in the Race section!




This is true, but I know a couple of guys running LS engines in old cars with carbs, and these wide LSA cams are making stupid power. There's a guy here locally with a carb'd 421 cube LS in '69 Nova with a cam very similar to one below and he's running very low 11's on motor. The engine doesn't act that rowdy, and it is actually pretty dang streetable, which I think is the point of the thread. It runs so well that it has made me wonder how it would work having some of those lobes put on a custom grind Pontiac camshaft.

Are you saying that you think this style cam is a compromise and is potentially leaving power on the table being that has to have a wide LSA being that it is an EFI cam?






To guys like you that know what they are talking about - no, they aren't considered old school technology. However, to a lot of average Joe car guys out there, they are. They've been told by magazines, the guy at their local motor machine shop, and lots of other places that you CAN'T run more that 9.5 : 1 in street, and the best cam out there is a Comp XE, and before that a Comp High Energy or Magnum.

About 20 years ago I had a #461 double hump (62cc) headed .060" over 350 SBC in a '68 Camaro. I bought the car from an older guy that built it pretty much as old school as you can. It had forged flat-tops with the little small valve reliefs, "pink" rods, steel crank. The heads were cut about .030" and were bowl ported, it has a high rise dual plane factory L-79 intake with a 650 DP and a set of Hooker Headers. It had the infamous "151" L-79 cam with a 1.6 roller tips and Z/28 springs. It was a 4 speed car, and that damn thing ran like a demon! I never got a completely clean pass back then because I never put it on slicks, but I managed some mid 12's at 111 - 113 MPH (which says it had more) while spinning the Mickey Thompson Indy Profiles that were on it. The car idled very mildly, the brakes worked great, and it never detonated. It was a very fun car in every way.

After having it a while, everybody and his brother told me how much power I could gain by putting a Comp 270H Magnum in it. I called Comp and told them my combo and it was said to be the biggest Magnum cam that you could run with power brakes and stock converter and would work well with my combination. I pulled the trigger and bought the cam, lifters, and springs and put them in one weekend. After we fired it up and broke in the cam, we were like OMG!!! This things sounds like as race car! I drove it around on the street, and it spun like crazy (like it did with L-79 cam), but I could just tell that it was going to be faster. It sounded awesome, so it had to, right? A few weeks later we took it to the track and the car slowed down. This bigger, better, modern cam would not rev anything like the L-79 did and just wasn't stronger really in any RPM range. Ok - I had to have done something wrong. I re-checked everything, but everything was right. I had a few guys that were more experienced than me look at it - re-checked the timing, re-set the valves, and everything was right. We played with jets, and could not get it run like it did before. It still ran OK, and sounded great, but the brakes weren't as good and it ran a touch hotter. I was driving it on a real hot southern summer day and I thought a I heard valve rattling when I wound it up in 1st leaving a stop sign. I talked to some people and told them my combo and we determined with the cut 62cc heads, small valve relief flattops,and being .060" over (360 cubes) that I was probably pushing a touch over 10 : 1 CR. I bought some Sunoco 110 and we cut it half and half with pump gas. I took it back to the track and sure enough it picked up about a tenth in the 1/4. The mid-range was stronger than it had ever been before, but it still never revved like it did with L-79 cam and I had shift at a lower RPM. It had been obviously been detonating, but I never heard it until that hot summer day. I ended up dropping the timing a little bit, and the problems went away, but it never ran like it did with before the cam change unless I bumped up the octane.

I never went back and dropped the CR to be more friendly with the Magnum cam, but I can't see where it would have been any faster than it was with the race fuel blend. Even if it had been a tenth or two faster, it wasn't as fun to drive and wasn't as streetable. That old 30+ year old cam (back then - almost 50 years old now! ) was much like those RAIV's, and just plain worked! It idled well, had plenty of vacuum, and truthfully, I wouldn't hesitate to a build a L-79 cammed SBC today as long as it had enough CR to take advantage of it.








Isn't more average power what you need in a TRUE street car? (Meaning a car that is built for the street that might go to the track sometimes, as opposed to a car that is built for low ET's but called a street car). The reason I ask is that I've been in street cars and actually built a few many years ago with Comp XE cams that ran pretty good, but had a narrow range of power. These cars ran pretty good at the track too, but they required low gears (4.10's) and pretty loose converters to run fast. That's fine for a street/strip car, but nothing I'd want to drive a lot. Power over a broader range is seems like the cure to that problem.

That said, I am not too close minded to listen to suggestions, recommendations, and other people's experiences with tighter LSA cams that make great power and are very streetable. What tighter LSA camshafts/lobe designs out there make power over with the same broad range as a cam with a wider LSA and is as equally streetable (good vacuum, low idle, no need for a big converter)?




Again, all of the above sounds exactly like what I (and a lot of other people) want out of their car. To put it bluntly, many of us want the cake and to eat it too! I want the car to be very streetable but I'm not satisfied with being a low 13, high 12 second car. I want the car to be fast but to act like it's not. That's what these these longer duration cams with wider LSA's in big inch engines with a healthy compression ratio seem to offer. I couldn't honestly care less about it sounding like a hot rod or race car. I'd rather it sound like a car with a mild street cam that drops jaws when it goes around a so-called hot rod or down the track. This doesn't seem to be what you typically get with a tighter LSA cam, correct?


If I understand you right, you are saying that a well designed cam with a tighter lobe separation can potentially make more power as long you are more interested in ET than streetability, meaning that you like most things, you have to compromise some power to have good street manners.

[Steve C.]

It wasn't long after I bought the car that the novelty of a 'numbers matching' daily driver was replaced with emphasis on performance. It was registered, safety inspected and spent more time on the street than a drag strip. Granted it wasn't meant as a highway cruiser and because of the compression ratio I did add a bit of race gas to our 93 octane available here in Texas, but that was no big deal as I lived near the local race shop and race gas was cheap back then and bought a 5 gallon jug of it now and then. Again, no big deal. As expected it had a nice wicked idle coupled with a loose converter, like many I thrived on it. Still do !

Yes, that was 251 degrees at .050". I agree with Cliff, too many under cam their Pontiac's.

Enough though about 400 engines.... back to boring 5000 rpm truck motor combinations

.

[67GTO4SPEED]

Thanks for that clarification! I see what you mean about grouping all that style of cam together, because I was guilty of that myself because I didn't know any better. I guess a part of that, for me, comes from something I was told by Jim Butler himself, years ago. He told me not long after they stopped selling the UD cams that they found that the Comp XE's were better in every way. I think looking back that he was just doing what most people do that are selling something. I know now that Butler stopped using UD cams because Harold couldn't keep him supplied. I guess you couldn't expect Jim to say "Well, the UD's were better, but we can't get them anymore."

I'd love to see a side by side test of the RAIV/Crower 60919 and the Voodoo 704 in the same engine. I do know from my own experience that a RAIV cam has a way larger RPM range that 2000 - 4800. I haven't actually used a Crower 60919, but I know a RAIV cam makes power much higher than 4800.

In your builds Paul, have you used the Voodoo 704 in a 455-467 with a RA manifolds?

[gtofreek]

Originally Posted by 67GTO4SPEED

Thanks for that clarification! I see what you mean about grouping all that style of cam together, because I was guilty of that myself because I didn't know any better. I guess a part of that, for me, comes from something I was told by Jim Butler himself, years ago. He told me not long after they stopped selling the UD cams that they found that the Comp XE's were better in every way. I think looking back that he was just doing what most people do that are selling something. I know now that Butler stopped using UD cams because Harold couldn't keep him supplied. I guess you couldn't expect Jim to say "Well, the UD's were better, but we can't get them anymore."

I'd love to see a side by side test of the RAIV/Crower 60919 and the Voodoo 704 in the same engine. I do know from my own experience that a RAIV cam has a way larger RPM range that 2000 - 4800. I haven't actually used a Crower 60919, but I know a RAIV cam makes power much higher than 4800.

In your builds Paul, have you used the Voodoo 704 in a 455-467 with a RA manifolds?

I really don't want to hi-jack Cliff's thread with Voodoo cam stuff, so maybe you could start a thread about this, and I will answer your questions there.