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CarolinaTZ

Racer Brown Cam

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Hi, I checked around so not to ask a redundant question but couldn't find anything. I have Racer Brown cam with:

 

110 SS56 - SS54

485-2

 

The numbers seem to be a combination of 2 different grinds...SS56 and SS54. Has anyone seen a number like this or know what the specs are? The date appears to be 1985.

 

Thanks,

Joe

Edited by CarolinaTZ

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If you don't have any luck with the numbers, you can put it in some V blocks, spin it and use a dial indicator to get lift. Then multiply that by 1.5 and there's your lift at the valve. You might be able to match up the intake and exhaust lift with a known Racer Brown profile that way...

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Since I'm posting I'll probably be wrong but I remember those a hot street grind. A lot of lift and short duration. I think somewhere in the 475 to 495 lift range but shorter than stock duration. I had one in a street car in the eighties and it was NOISY. The aggressive ramps seemed to about double the valvetrain noise. I'll have to see if I can find my original BRE book as they were listed in it.

 

Cary

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Thanks for the help, guys. How well did the cam perform? This cam is in my motor that Tom Wyatt built so, I assume it's a good cam for a turbo motor. Do turbos like a lot of overlap or not? The steep profile/high lift may explain some wear on some of the lobes. Can cams be repaired? If so, who do you guys recommend? I haven't taken any measurements yet...this is based on visual.

Edited by CarolinaTZ

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"Can cams be repaired? If so, who do you guys recommend?"

 

Paeco in Birmingham Alabama markets a hardfacing compound welded on journals and cam lobes (price of repair is based per lobe/journal)

 

The issue is whether or not you can get the orginal grind replicated! Racer Brown used assymetric lobe profiles and once welded over, if not shadow-profiled (Isky can do this...) and then properly programmed into the grinding machine will be lost forever.

 

It may simply be cheaper to map the specs as best you can, and then talk to Isky or Sunbelt about what grind they have available to approximate it. They are the only two that I know of that are currently grinding assymetric cam profiles for the L-Engine.

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My cam from delta is an assymetric, but it's not a new grind...it's very obvious from looking at the lobes what type it is, though. I would imagine it's a knock off of another cam from the late 70's early 80's, but Isky and Sunbelt are not the only ones.

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News to me, then it would be Delta Sunbelt and Isky. Other stuff I've seen is old tech bumpstick profile. If Delta knocked something off, it would be Racer Brown if it was the 70's. They were the only one selling asymetric grinds for the L Series then. Isky didn't go assymetric till the early 80's.

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News to me, then it would be Delta Sunbelt and Isky. Other stuff I've seen is old tech bumpstick profile. If Delta knocked something off, it would be Racer Brown if it was the 70's. They were the only one selling asymetric grinds for the L Series then. Isky didn't go assymetric till the early 80's.

 

You may still be correct, Tony. As you know, you can't tell if a grind is asymmetric or not just by looking at the lobe - you have to map the actual lift that occurs at the valve vs engine rotation. Because of the way the geometry changes as the lobe wipes over the rocker, the lobe for our engines ends up looking asymmetric just to keep the actual lift profile symmetrical.

 

My current cam lobes look for all the world to be asymmetric, but here's a plot of the opening/closing rates at overlap - the ramp rates are pretty much identical. When I mapped the whole thing I was really surprised at how symmetrical the intake and exhaust lobes were - not what I expected to find!

cam%20overlap.jpg

Edited by TimZ

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Yeah Tim, I know. I'm not going too argue the point, there's just a time when you stop arguing and let people say/believe what they want.

 

Profile the cam? What's that? It doesn't LOOK like a VW cam, it's got a different ramp coming and going, it must be assymetric. What can you do?

 

Let them believe what they want.

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Yeah Tim, I know. I'm not going too argue the point, there's just a time when you stop arguing and let people say/believe what they want.

 

Profile the cam? What's that? It doesn't LOOK like a VW cam, it's got a different ramp coming and going, it must be assymetric. What can you do?

 

Let them believe what they want.

 

Okay - WHO ARE YOU AND WHAT HAVE YOU DONE WITH TONY???

 

:mrgreen:

 

...I knew I wasn't telling you anything new - just wanted to throw it out there

Edited by TimZ

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Mine were sold to me with the description "snaps the valve open, closes it slowly" and I was told that it would be less likely to float the valves, etc. But I just like to argue no matter what the point is... :rolleyes: I was however shown the actual lobe when told it was asymmetric.

 

Just checked Delta cams website, they advertise asymmetrical lobes as well and describe what makes a cam asymmetric:

http://www.deltacam.com/tech.php

In both engine designs, the rocker arm or lash cap compresses the valve spring to open the valve. As the cam continues to rotate, the force is relieved and the valve closes.Usually, the contour on both sides of the lobe is the same (the contour, or profile, controls the acceleration of the valve). However, if it differs from side to side, the camshaft is said to be asymmetric. The Ford 2300cc engine has asymmetric lobes. If the intake and exhaust lobes have different profiles, the camshaft is referred to as dual pattern design. Some of the so-called "mileage" camshafts are dual pattern.

 

I think the fact that the open and close rates might be similar is not a defining characteristic of a symmetric cam. The symmetry of the cam relates to the symmetry of the lobe. Maybe the reason that asymmetrical cams work better is because symmetrical cams have asymmetric open and closing characteristics. Certainly would seem to be the case, wouldn't it Tim? If your cam with obviously different ramps has similar lift and closing rates, seems kind of impossible for a cam with symmetrical lobes to do the same, and if the goal of most of these cams is to open the valve faster and close it slower, then a symmetrical cam would open the valve slower and close it faster.

 

Regardless of any of that, I don't get why anyone would think that Racer Brown should have discovered something in the 70's, this thing would be common knowledge and NOBODY else but Sunbelt would have thought "Hey, that's a pretty good idea! Let's do THAT!" in the intervening 40 years. That strikes me as not likely.

Edited by JMortensen

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"NOBODY else but Sunbelt would have thought "Hey, that's a pretty good idea! Let's do THAT!" in the intervening 40 years. "

 

Never said that, sometimes your attitude is...poor.

That's the most charitable I can be at this point.

 

Never said it, you're just plain being an ass misstating it like that.

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Mine were sold to me with the description "snaps the valve open, closes it slowly" and I was told that it would be less likely to float the valves, etc. But I just like to argue no matter what the point is... :rolleyes: I was however shown the actual lobe when told it was asymmetric.

 

Just checked Delta cams website, they advertise asymmetrical lobes as well and describe what makes a cam asymmetric:

http://www.deltacam.com/tech.php

 

 

I think the fact that the open and close rates might be similar is not a defining characteristic of a symmetric cam. The symmetry of the cam relates to the symmetry of the lobe. Maybe the reason that asymmetrical cams work better is because symmetrical cams have asymmetric open and closing characteristics. Certainly would seem to be the case, wouldn't it Tim? If your cam with obviously different ramps has similar lift and closing rates, seems kind of impossible for a cam with symmetrical lobes to do the same, and if the goal of most of these cams is to open the valve faster and close it slower, then a symmetrical cam would open the valve slower and close it faster.

 

Regardless of any of that, I don't get why anyone would think that Racer Brown should have discovered something in the 70's, this thing would be common knowledge and NOBODY else but Sunbelt would have thought "Hey, that's a pretty good idea! Let's do THAT!" in the intervening 40 years. That strikes me as not likely.

 

This position just doesn't make sense - you are saying that it only matters what the cam lobe looks like, not how it effects the opening and closing of the valves. If you can't tell anything about the performance of the cam by talking about its "symmetry" then there is no point in talking about it at all. You might as well be talking about what font was used to stamp the cam code onto it.

 

You missed the salient point in the Delta Cams definition -

"Usually, the contour on both sides of the lobe is the same (the contour, or profile, controls the acceleration of the valve)"

 

...it's the shape of the lobe that results in a given acceleration at the valve that they are referring to, not just the shape of the lobe, devoid of any other information. The "profile" as stated refers to the motion at the valve, not just the visual characteristics of the lobe. So, if the shape of the lobe results in the same valve motion on the opening and closing sides, then it is symmetrical. No other definition is worth talking about.

Edited by TimZ

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I appreciate you guys chiming in...I definitely learned some things. I'll be installing new stem seals soon and will look more closely at the condition of the cam. In the meantime dapiper (small world, David) has offered to send me the specs on this cam which will help me know what I have. texis30O, I saw your youtube videos...both of them...a year or 2 ago...before I even had this car. Very cool videos...looks like a very nice - and fast - Z you have there! Do you know what cam you have?

 

Joe

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This position just doesn't make sense - you are saying that it only matters what the cam lobe looks like, not how it effects the opening and closing of the valves. If you can't tell anything about the performance of the cam by talking about its "symmetry" then there is no point in talking about it at all. You might as well be talking about what font was used to stamp the cam code onto it.

 

You missed the salient point in the Delta Cams definition -

"Usually, the contour on both sides of the lobe is the same (the contour, or profile, controls the acceleration of the valve)"

 

...it's the shape of the lobe that results in a given acceleration at the valve that they are referring to, not just the shape of the lobe, devoid of any other information. The "profile" as stated refers to the motion at the valve, not just the visual characteristics of the lobe. So, if the shape of the lobe results in the same valve motion on the opening and closing sides, then it is symmetrical. No other definition is worth talking about.

My position makes perfect sense. The cam lobe is either symmetrical in shape or it is not. If I weren't talking about the cam lobe, and were actually talking about valve speeds or cam timing, I might refer to that as "valve speed symmetry" or "valve timing symmetry" but that is not what people are talking about when they say "asymmetrical camshaft." While your description of valve timing events might be more accurately called "symmetric", that has no bearing on the common meaning of the term asymmetric cam. The common definition refers to the shape of the lobe and the ramps. Some evidence follows. This took about a few minutes to look up on google. You can try and find some that say that asymmetric cam refers to valve speed or valve timing, but based on what I just found I think you'll be looking for a while.

 

http://www.hotrodder.com/kwkride/cambasic.html

"Asymmetrical - An Asymmetrical cam has opening and closing ramps that are different. These profiles are usually found on high performance cams and offer a high velocity opening and a lower velocity closing ramp in order to snap the valve open quickly and then set it back down more gently. "

 

http://www.cartechbooks.com/vstore/showdetl.cfm?st=0&st2=0&st3=0&CATID=23&Product_ID=3540&DID=6&chapter=10625

"If you are degreeing a cam with asymmetric cam lobes, you cannot use the lobe centerline method. After precisely setting the degree wheel to TDC as indicated in the text, mark the 0.050-inch timing figures on your degree wheel and verify them with your cam card"

Why can't you use the lobe centerline? Because the lobe isn't symmetrical.

 

http://www.hotrod.com/techarticles/camshaft_tips_definitions/index.html

"Definition: An asymmetrical camshaft features a lobe shape or profile that is different on the opening side than the closing side of the same lobe. For example, a camshaft could feature a very rapid valve opening profile, but when the valve is closing on the same lobe, the shape could be extremely smooth and gentle."

 

http://www.tildentechnologies.com/Technical/CamBasics.html

"Asymmetric Lobe - the opening and closing side of the cam are different"

 

http://books.google.com/books?id=bE111229meQC&pg=PA72&lpg=PA72&dq=asymmetric+cam+lobe&source=bl&ots=g634XxwfPU&sig=siK8162QqdHZJnfz0Fywus2CnkY&hl=en&ei=jU7XTL3HE5CosAO-zrSNCw&sa=X&oi=book_result&ct=result&resnum=2&ved=0CBYQ6AEwATgU#v=onepage&q=asymmetric%20cam%20lobe&f=true

 

http://www.circletrack.com/techarticles/ctrp_0701_camshaft_design_science/index.html

"An asymmetrical lobe refers to opening and closing ramps that are not identical."

 

Here's one that even refers to what you and Tony are talking about.

http://www.metricmechanic.com/catalog/dual-profile-asymmetrical-cam.php

"If you look at the BMW intake and exhaust cam lobes, they will appear to be a mirror image of one another and ground with an asymmetrical profile. When you plot out the lift curve on a piece of graph paper, you'll discover that the asymmetrical BMW lobe looks like a symmetrical bell shaped curve. The reason this phenomena occurs is because as the nose of the cam wipes across the curved foot of the rocker arm, the rocker arm ratio changes from a low of 0.9:1 to a high of 1.6:1 (with an average of 1.25:1). So, if we combine a fairly symmetrical lobe with BMW's variable rocker arm ratio we end up generating an asymmetrical cam map."

 

Is everybody else wrong, or are you and Tony wrong?

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I should have just taken Tony's position.

 

I'll just say this - from the context of the posts up until mine, it's really clear that everybody (including you, Jon) was talking about the symmetry of the valve opening/closing rates, and assuming that you could tell this by looking at the lobe shape and whether its symmetrical or not. You can't. Not on an L-series cam.

 

Many other engines do have valvetrain geometry that results in the shape of the lobe being analogous to the valve opening/closing profile, which is most likely why the links posted above made this generalization.

 

Regardless, trying to help CarolinaTZ ID his cam by telling him it's "asymmetrical" by your definition is pointless. I defy you to find an L-series cam that doesn't have asymmetrical lobes. There are, however, L-series cams that have symmetrical valve opening/closing profiles and those that have asymmetrical valve opening/closing profiles, and that's what everybody in this thread was referring to.

 

Mine were sold to me with the description "snaps the valve open, closes it slowly" and I was told that it would be less likely to float the valves, etc. But I just like to argue no matter what the point is... I was however shown the actual lobe when told it was asymmetric.

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My position makes perfect sense. The cam lobe is either symmetrical in shape or it is not. If I weren't talking about the cam lobe, and were actually talking about valve speeds or cam timing, I might refer to that as "valve speed symmetry" or "valve timing symmetry" but that is not what people are talking about when they say "asymmetrical camshaft." While your description of valve timing events might be more accurately called "symmetric", that has no bearing on the common meaning of the term asymmetric cam. The common definition refers to the shape of the lobe and the ramps. Some evidence follows. This took about a few minutes to look up on google. You can try and find some that say that asymmetric cam refers to valve speed or valve timing, but based on what I just found I think you'll be looking for a while.

 

.

.

..

...

 

Here's one that even refers to what you and Tony are talking about.

http://www.metricmechanic.com/catalog/dual-profile-asymmetrical-cam.php

"If you look at the BMW intake and exhaust cam lobes, they will appear to be a mirror image of one another and ground with an asymmetrical profile. When you plot out the lift curve on a piece of graph paper, you'll discover that the asymmetrical BMW lobe looks like a symmetrical bell shaped curve. The reason this phenomena occurs is because as the nose of the cam wipes across the curved foot of the rocker arm, the rocker arm ratio changes from a low of 0.9:1 to a high of 1.6:1 (with an average of 1.25:1). So, if we combine a fairly symmetrical lobe with BMW's variable rocker arm ratio we end up generating an asymmetrical cam map."

 

Is everybody else wrong, or are you and Tony wrong?

 

Jon,

 

Almost all the links you posted to the definition of asymmetrical cams are referring to cams that would be used in engines with relatively fixed/constant rocker ratio, which would also result in a symmetrical cam giving symmetrical valve opening/closing.

 

Maybe the nomenclature doesn't agree from one source to the next, but I would have to agree that almost all L6 cams would have to have asymmetrical "cam profiles" to optimize the changing rocker ratios for valve velocity/acceleration (as mentioned in your BMW quote.)

 

For the Original Poster,

 

Why not buy some v-blocks as Jon mentioned earlier, get a dial indicator and a degree wheel and measure the cam all the way around. Then model the valve movement as the cam acts through the rocker arm, and check out what the lift is.

 

At that point you would have more information than the original cam card had. (might be more work than you signed up for though.)

 

Also, if anyone is willing to take measurements of their cam (don't care if it's stock or regrind) and send them to me, I would be happy to model the resultant lift at the valve.

Edited by olie05

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People who use the term "symmetric cam" are talking first and foremost about the shape of the lobe, I think that is clear based on the links I posted. You're partially right though Tim. I assumed that the shape of the lift curves when plotted would be roughly analogous to the shape of the lobe. So when I said I had two cams that were asymmetric, I made that distinction based on the shape of the lobe, because "everyone knows how to tell an asymmetric cam". I learned something about my erroneous assumption about how the cams really act from your post and I appreciate the education. Regardless, the cam that acts like we are all describing with regards to timing is still going to have an asymmetric profile, with a fast lift ramp and a slow close ramp.

 

Tony's assumption that Delta, Sunbelt, and Isky make asymmetrically timed cams for the L series and "others" use "old tech bumpstick profile" still strikes me as wrong and if I were one of those "other" cam manufacturers I'd be insulted by it. As you pointed out Tim, virtually every cam that you can find for an L series is asymmetrical. Don't you think it would be a strange thing to assume that every cam manufacturer had gone through and found the proper profile to get equal timing events on the open and close of the valve, and then make all of their cams a variation of that basic profile to maintain their symmetry, especially while simultaneously advertising that their asymmetric cam profile opens the valve quickly and closes it slowly? Are they all liars, or are they all too stupid to figure it out, while simultaneously being smart enough to ensure the symmetry of all of their L cams? No customer with a race car ever plotted it out and came back and said: "Hey, this thing actually opens and closes pretty evenly"? And no cam manufacturer ever cared enough to put their cam in a car with a degree wheel and a dial indicator and check what the thing actually does on the engine and then thought to himself: "Hey, what if we modified this thing to actually open the valve quickly and close it slowly, in the same way that works with our cars that don't have the curved rocker contact surface throwing the cam timing off?" None of those cam grinders ever put it through a computer model? Really? I dunno. It seems like you have to have an awfully low estimate of a lot of peoples' integrity or intelligence to believe such a thing.

Edited by JMortensen

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I dunno, in the pushrod realm, and assymetric cam was quite a revolutionary thing.

 

To discuss what a cam manufacturer does or doesn't do when you aren't one seems arrogant and presumptious, IMO.

 

Ron seemed straightforward about their R&D: "We copied a BMW profile just to have something to offer initially. It's amazing to see our profiles from back then directly copied on other people's cams, even to this day! They make power I guess, but they aren't right. When we were working with Electromotive ten years later, Nissan wouldn't give us ANY information, so we had to shadow-profile their stock cams and that's when we realized they were doing things quite a bit different from what BMW did, the profile was all wrong for the Nissan Engine and I had to totally re-engineer the ramps to get an assymetric valve action. From that, we changed everything we did on the L-Cams."

 

Like I said before: Plenty of IMMITATORS, but few INNOVATORS. If it runs and makes power, and you can just rip it off from someone else, why ENGINEER it? Yeah, the Chinese are the only ones that do that, right? It would NEVER happen in the USA with something as complex as a camshaft... :rolleyes:

Edited by Tony D

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To discuss what a cam manufacturer does or doesn't do when you aren't one seems arrogant and presumptious, IMO.

 

Like I said before: Plenty of IMMITATORS, but few INNOVATORS. If it runs and makes power, and you can just rip it off from someone else, why ENGINEER it? Yeah, the Chinese are the only ones that do that, right? It would NEVER happen in the USA with something as complex as a camshaft... :rolleyes:

Glad we cleared that up.

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Concentrate on that which doesn't blow your argument out of the water? Interesting that's your only comment now... :huh:

 

I can delete those portions if that makes you feel better John, but they both bring out two salient points to your ad hominems about my comments from earlier. What, is this a goose-gander situation?

 

I mean, facts of the matter are that many cam manufacturers simply rip off profiles. Isky did it, and admits it. And they also went back to revisit the design when it became obvious they needed to. And the evidence remains clear today that many other cam manufacturers HAVE NOT done this.

 

Which directly addresses your sarcastic comment about assuming other manufacturers being competent enough chack what their designs do on an engineering level. Well perhaps THEY HAVEN'T...the evidence exists that some still have the SAME grinds they stole back in the 70's. Perhaps it's simply as Ron said: "they make power I guess, but they aren't right"---so their criteria may simply be limited to functionality, defined as power production. For many people that is all that matters.

 

Never ASSUME total competence from a guy simply because he has a shingle hung out. Limited competence, or performance is one thing, engineering backed knowledge of what is going on is something totally different. I limited my comments to what I have actually seen in my own investigations, or gained from discussions directly with people who design and manufacture the product, not off some website. From what I have seen, Ron's assessment seemed valid, so that is probably a bit more indicative of the state of the manufacturing environment regarding camshafts. I only know people from three manufacturers, Erson, Crane and Isky, perhaps you know more and have more insight than I do...I don't know. But from what I've seen and discussed over the past 15 or so years I belive my statements to be based on fatual conversations and evidence from my own investigations and not supposition and wild-arse guessing based on assumptions.

 

The last point in your quote punctuates that: Finding a competent engineer to actually start something from scratch is exceedingly difficult. To assume simple human nature to imitate is not applicable or done in something as complex as camshaft design seems foolish to me, it's often been said that China rips off things...but they are simply human and cam manufacturers in the USA are the same humans (as far as I know) and that they would have the same tendencies to 'save work'.

 

That it addresses things salient to the discussion is a separate, additional benefit.

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