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Author Topic: Why the lack of published cam specs  (Read 4378 times)

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dave brode

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Why the lack of published cam specs
« on: June 22, 2018, 10:39:39 AM »

All,

Being a car guy, it seems absurd that cams are advertised with no seat timing specs. It would be quite rare to see car engine cam advertised without the seat timing being listed. Do they think that too many numbers would overwhelm the common man's brain? 

Andrews, oddly, [to me] lists duration at .020". That tell a little story, but still doesn't tell us all that much about the ramps. The .020" rise numbers are normally used for solid cams in the car world, and .006" rise is what's used for hydraulic grinds.

I chuckle what I read a fellow claiming that "this" cam is close to "that" cam, as he compared the .053" rise numbers. The seat timing could vary by a huge amount...

I have asked several cam grinders for seat timing info. To this point, only Zippers has supplied me any info. [thanks Pete]

I remember 20 yrs ago, it was rare to even see LSA and/or L/C listed for HD cams. It's not like one can't calculate it. At least that has changed in some cases. 

Dave
p.s. - I'd bet big $ that some racers aren't using solid grinds in the TCs, but I haven't seen any. I do remember, before S&S buy-out, when Crane had a drop in solid lifter for the '87 up chev/HD.  Some of the hyd grinds that are listed for TCs would be seen as being absurd in the car world.
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HD Street Performance

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Re: Why the lack of published cam specs
« Reply #1 on: June 22, 2018, 10:54:25 AM »

Solids have been tried by Bonneville efforts in a TC. Ironically they grow less than an evo, all things considered including pushrod growth
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dave brode

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Re: Why the lack of published cam specs
« Reply #2 on: June 22, 2018, 11:15:49 AM »

I remember from HTT, someone heated parts in an oven and the difference in cyl vs p-rod growth was small. Less than scientific but interesting.
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MCE

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Re: Why the lack of published cam specs
« Reply #3 on: June 22, 2018, 11:57:31 AM »

Published specs are almost meaningless (almost). It's a general guideline at best.

One would have to plot the lobe's lift vs. degrees to do any meaningful comparisons.
I haven't found a cam maker that will provide cam-pro files. You have to buy the
cam and get the data yourself.

"Advertised" means it's just like any other advertisement.   



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dave brode

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Re: Why the lack of published cam specs
« Reply #4 on: June 22, 2018, 12:59:37 PM »

Matt,

I agree that merely having some sort of seat timing in addition to the .053" timing isn't like you cam doctored it [or used a wheel and your brain], but it would still give some idea of the opening and closing ramp designs, in general. I'd like to know what's happening at less than .053" rise and make my own decisions.

Imo, just because they don't supply us with more doesn't mean we should just accept that. Most major car cam companies publish duration at .006" [hyd only] .020", .050" and .200" in their lobe listings.  Some will give you more than that if you ask.


Thanks

Dave
p.s. - and what's with the .053" number vs .050"? Anyone know why that became the std? Curious.....
 
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dave brode

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Re: Why the lack of published cam specs
« Reply #5 on: June 22, 2018, 01:08:35 PM »

Matt,

I admit that I realize that the end results might be better if I became a "here's my credit card" guy. LOL

Dave
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MCE

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Re: Why the lack of published cam specs
« Reply #6 on: June 22, 2018, 01:51:33 PM »

Matt,

I agree that merely having some sort of seat timing in addition to the .053" timing isn't like you cam doctored it [or used a wheel and your brain], but it would still give some idea of the opening and closing ramp designs, in general. I'd like to know what's happening at less than .053" rise and make my own decisions.

Imo, just because they don't supply us with more doesn't mean we should just accept that. Most major car cam companies publish duration at .006" [hyd only] .020", .050" and .200" in their lobe listings.  Some will give you more than that if you ask.


Thanks

Dave
p.s. - and what's with the .053" number vs .050"? Anyone know why that became the std? Curious.....

None (that I know of) will give you the actual lobe data files. As far as 'what's happening below .053"?
Not much. That's why they (somewhat) standardized the .050/.053" measurement. (the .003 difference
is almost insignificant imo)

But that still doesn't tell you enough to make any kind of real comparison. You could run Three cams with
identical .053 durations and lifts and get Three completely different sets of results.

It's the area under the curve that we're mostly interested in. That translates into the valve curtain area that's
presented to the cylinder. Then, there's that area at 'x' degrees of crank rotation. And to further
complicate things, the piston's position (and speed) at that given crank degree (instance).

It gets pretty intense in a hurry. Engine analyzer programs help put some of it in perspective but at
the end of the day (week/month/year), trial and error on a dyno will sort the rest of it out if you're
willing to spend the time.

For 97% of the people, taking what they give you and running it is good enough.
« Last Edit: June 22, 2018, 02:01:36 PM by MCE Performance »
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MCE

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Re: Why the lack of published cam specs
« Reply #7 on: June 22, 2018, 02:10:40 PM »

A small percentage of engine builders are smarter than the engineers the cam companies employ.
Or very few are willing to spend the 100s of hours required to second guess them. Unless you're
competing in some (big money) class racing, it's just not worth it in most cases.

PS: Spending 100 hours (for example) to gain a couple HP is not worth it to most people. To me it is,
but my time (like everyone else) is limited. You don't generally get paid for that time either. (So there's
that too)

I don't do this for the money, but there's still only so much time in a day.
« Last Edit: June 22, 2018, 02:29:31 PM by MCE Performance »
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dave brode

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Re: Why the lack of published cam specs
« Reply #8 on: June 22, 2018, 04:12:29 PM »

MCE wrote;

"But that still doesn't tell you enough to make any kind of real comparison. You could run Three cams with
identical .053 durations and lifts and get Three completely different sets of results."

Exactly, and that's my whole point! And w/o the data, we can't know w/o buying first.

Btw, I wasn't second guessing anyone. I just wish to know what I'm buying.

Thanks for your input.

Dave
p.s. - Understood on .050" vs .053", I was just curious as to why that tappet rise was chosen
 
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MCE

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Re: Why the lack of published cam specs
« Reply #9 on: June 22, 2018, 04:26:49 PM »

.050/.053 was chosen because what happens below .050" means nothing. It eliminates skewing the duration
numbers for advertising purposes, which helps you compare apples to apples. Ask a couple cam manufacturers what they
recommend. Or ask someone that's built successful combos like the one you're building.

Why was .050 specifically chosen? It's likely that they got a group of engine builders, engineers and whoever else to agree
on a number. Zero obviously isn't a good choice because then, you really wouldn't know what you were getting. They had
to decide on a number that was far enough off of zero but not too far from zero.

Intake close, Overlap, and lobe separation are things to consider when choosing a cam. But the tech departments at the
cam companies are a much better resource than going it alone, especially if you're not well versed in this type of thing.

« Last Edit: June 23, 2018, 09:26:38 AM by Fired00d »
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Nocvo

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Re: Why the lack of published cam specs
« Reply #10 on: June 22, 2018, 06:15:13 PM »

Aside from not making it too easy for someone to copy your cam design translating the entire cam data onto paper would be more real-estate than the surface of the box and how many people would truly understand it all anyway?
Was looking at two cams yesterday, 32H and 590PS, just in lobe profile alone the difference is huge, open and close barely touches on the differences possible.
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MCE

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Re: Why the lack of published cam specs
« Reply #11 on: June 22, 2018, 11:22:39 PM »

exactly.
« Last Edit: June 23, 2018, 01:04:57 AM by MCE Performance »
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dave brode

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Re: Why the lack of published cam specs
« Reply #12 on: June 22, 2018, 11:36:59 PM »

When someone "steals" a lobe design, they sure don't need the published numbers to do it. 
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MCE

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Re: Why the lack of published cam specs
« Reply #13 on: June 22, 2018, 11:43:27 PM »

You generate them on a machine like Audie Cam Pro. You can also load those the files into Dynomation
if you wanted to.
(you still need is a lobe centerline number, That's the only spec you really NEED)
« Last Edit: June 23, 2018, 01:07:21 AM by MCE Performance »
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dave brode

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Re: Why the lack of published cam specs
« Reply #14 on: June 22, 2018, 11:57:53 PM »

Of course. Easy to steal.

Back to seat vs .053". the difference in .006" and .053" duration on two lobes with the same .053" duration could well differ by 6 or 8 degrees. The .200" number would be an indicator too. I'd like to have that info. Maybe I'm just used to car cam spec. .006", .050", .200". Maybe I'm the only guy that thinks it's not asking too much.

Would it make me able to choose more wisely? Maybe not, but I'd just like to be able to gaze at the numbers and say golly gee. LOL.

Fwiw, for anyone that's not seen one and cares to, here is a typical lobe listing giving rated duration [.006" hyd, .020" solid], .050", .200". Why should we be happy with less? http://www.compcams.com/Technical/Catalogs/CamLobeMasterCatalog.pdf

I didn't mean to ruffle anyone's feathers.
Sincerely,
Dave   
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MCE

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Re: Why the lack of published cam specs
« Reply #15 on: June 23, 2018, 12:26:14 AM »

Quote
the difference in .006" and .053" duration on two lobes with the same .053" duration could well differ by 6 or 8 degrees.

Not really.

But It really doesn't matter. There's virtually no flow going on below .053, and even
if there was, it's not going to be significant enough to make any difference one way or
the other.

I don't get why you're so hung up on what goes on under .050 lift. It's called the lobe flank and
there's little to nothing happening there!!! (Thats why they wait to start measuring at .050,
measuring at .006 just gives a false illusion of more duration (no real flow happens until over .050
at least on an intake port. EX is a little different, but not all that much)
« Last Edit: June 23, 2018, 12:54:38 AM by MCE Performance »
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MCE

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Re: Why the lack of published cam specs
« Reply #16 on: June 23, 2018, 12:37:16 AM »

Flow a port at .006" lift one time. There ain't much of anything there. No real flow
happens below .050 (give or take). So any advertised duration taken at those lifts
is meaningless. .050 is just a number they picked out of thin air and everyone
follows that recommendation.

Kinda like flowing ports at 28" of depression. That too is just a number that everyone
agreed to use, so things would be 'pseudo-standardized'.
« Last Edit: June 23, 2018, 12:47:49 AM by MCE Performance »
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Nocvo

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Re: Why the lack of published cam specs
« Reply #17 on: June 23, 2018, 04:04:07 AM »

Even with more data points in the cam description it still won't tell the average punter bugga all, horses for courses so choose wisely or ask the right people.
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prodrag1320

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Re: Why the lack of published cam specs
« Reply #18 on: June 23, 2018, 08:09:18 AM »

I designed my cams in my fuel bike,did a good job I guess,fastest in the world & first in the 6`s (6.85)

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Re: Why the lack of published cam specs
« Reply #19 on: June 23, 2018, 08:42:23 AM »


I may have misconstrued what the OP was saying, but I took it to mean the interest was more about the severity of the closing and opening of the valves (which is a big issue on stock TC's IMHO), and not about duration.  The profile of the ramps isn't something you can easily discern from any of the specs commonly listed, so someone seeking to find a cam with less severe ramps can't just compare specs.  Of course I could be wrong about the intent of the OP, if so please ignore this post.

JMHO - Jerry
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dave brode

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Re: Why the lack of published cam specs
« Reply #20 on: June 23, 2018, 10:40:20 AM »

Thank you, Jerry. You are correct. Example, 252* is a popular intake duration. The chance of every 252* lobe having the same seat timing , or .200" duration is unlikely. There are other examples, but it would be interesting to see the numbers on say an SE 259 and a Wood TW-8 lobe, both 246" at .053".

Then again, I do admit that a lobe could be symetrical, or assymetrical, so even lobes with the same seat and ,200" duration could be different.

Matt, I'm not about to argue cam design or flow bench findings with you. I still believe that we deserve to have the same level of [perhaps meaningless? LOL] info that car cam companies publish. 


Thank you all.
Dave




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MCE

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Re: Why the lack of published cam specs
« Reply #21 on: June 23, 2018, 10:51:33 AM »

Even with more data points in the cam description it still won't tell the average punter bugga all, horses for courses so choose wisely or ask the right people.
Exactly.

Most people wouldn't have a clue what they're looking at even if they did have all the
data points. I've been doing this chit over 45 years, and i'm still learning (thats what keeps my interest)

The only way to really know "what your're buying" is ask the right people, then stick them in the motor
and dyno it. (you can spend weeks/months/years hunting for that elusive couple extra HP/TQ)

The other alternative is, generate the lobe profile (cam pro), load that into the simulator and see what
you get. At the end of the day, you'll have to dyno the real thing or run it down the track like Kirby does.

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HD Street Performance

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Re: Why the lack of published cam specs
« Reply #22 on: June 23, 2018, 11:01:24 AM »

Dave, you are right. There is a void in the information supplied. Being as many are made by Andrews and the buyers that get their name and part number attached to them are not experienced in the technical aspects a lot of the grinds (lobe profiles) have similar ramps and intensity or in some cases identical other than a LC or a lift number changed a little.  Others grinding them are CompCams (and Lunati) and S&S. There are some small specialty houses as well. None that I am aware of provide the data like the car guys get. As crude as it may seem you can place them between centers and use a degree wheel and dial indicator, rig up a deal to turn them at 1/2 CS speed. Better than nothing if you don't own a cam doctor. The cam doctor will get you more accurate data but not sure if you can get the true LC angles. I don't own one. I just use empirical data, results from builds using my heads, Dynomation, and Pipemax.
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MCE

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Re: Why the lack of published cam specs
« Reply #23 on: June 23, 2018, 11:05:42 AM »

Thank you, Jerry. You are correct. Example, 252* is a popular intake duration. The chance of every 252* lobe having the same seat timing , or .200" duration is unlikely. There are other examples, but it would be interesting to see the numbers on say an SE 259 and a Wood TW-8 lobe, both 246" at .053".

Then again, I do admit that a lobe could be symetrical, or assymetrical, so even lobes with the same seat and ,200" duration could be different.

Matt, I'm not about to argue cam design or flow bench findings with you. I still believe that we deserve to have the same level of [perhaps meaningless? LOL] info that car cam companies publish. 


Thank you all.
Dave

Wanting knowledge is is great. If you really want to understand this stuff, I suggest getting a simulator
program and start playing around with it. You won't get any meaningful information from the cam maker
(other than dyno results from people that have tested) You need the Cam Pro data, they WON'T give that
out, so why bother? Get a Cam Pro and generate the files if you want that stuff, that's the only other way.
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MCE

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Re: Why the lack of published cam specs
« Reply #24 on: June 23, 2018, 11:14:51 AM »

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Nocvo

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Re: Why the lack of published cam specs
« Reply #25 on: June 23, 2018, 01:46:48 PM »

By average punter I ment mugs like me not you blokes who live and breathe this stuff, I understand what Dave is saying as well, after looking at Matt's link to his analyser I see there could be a little inclusion on the box that may be helpful to some, by that I mean a little wave gragh that shows intake and exhaust lift over duration, but as Matt said that is not information the cam owner wants to share.
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MCE

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Re: Why the lack of published cam specs
« Reply #26 on: June 23, 2018, 02:44:09 PM »

The average 'user' really doesn't need (or care) to know some of this stuff. They only care about the end result.
If you fall into that camp, just find someone that does know it and leave it to them.


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Nocvo

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Re: Why the lack of published cam specs
« Reply #27 on: June 23, 2018, 04:06:21 PM »

The average 'user' really doesn't need (or care) to know some of this stuff. They only care about the end result.
If you fall into that camp, just find someone that does know it and leave it to them.
I like to know the why of things at times, well enough to make some sense of it, thanks for sharing your knowledge, I won't be running out to make my own cam design but I do find cam topics interesting.
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TIMINATOR

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Re: Why the lack of published cam specs
« Reply #28 on: June 23, 2018, 09:31:20 PM »

Dave: I feel your pain! All of the HD cam companies could, but don't choose to provide the info that almost all of the car cam companies do. I have never gotten a straight answer from any of the companies that don't provide much (or any) advertised info either. We do not buy any cams from those companies, ever!
The cam "advertising wars" were heating up in the late 50s, so Ed Iskenderian (Isky Cams) came up with the .050 lift/ duration advertising figure back in the early 1960s (Yep, I'm old!) to "level the playing field", he figured that meaningful port flow was actually happening at .050" and that figure would provide more accurate duration info to the consumer. Crane Cams owner Harvey Crane, in the 70s, coined the term "intensity" to describe ramp rate differences from .050" to .200" so "joe average" could get an idea how "rampy" (therefore having more "area under the curve") a cam is in relation to another cam.
Lift and duration only are but a small bit of info you actually need to select the proper cam for your engine. Lobe separation and advance are just as important, and not usually stated, but can be easily calculated if seat timing is provided.  Competition Cams is one of the few companies that publish all lobe; lift/duration/shape/characteristics in one book. Crane tried that for one year in about 2005 and then hasn't done it since.
We Cam Dr. analyze most of the cams that come through here (automotive and HD), and have for 25+ years, thats why we use the cam companies that we do and leave the junk and "companies with something to hide" to the uncaring. We also don't select cams by "how they sound in another bike." Harsh, but true.  TIMINATOR



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TIMINATOR

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Re: Why the lack of published cam specs
« Reply #29 on: June 23, 2018, 09:47:56 PM »

I also agree with Dave that two cams with the same .053" duration can easily be 6 to 8 degrees different at .006" lift. You only need to compare the same old, same old "house brand" (40+ year old automotive grinds) cams to more modern Comp Cams grinds to see that. I have one of those in the shop that I refused to install for a customer's engine.
If both cams have the same .050/.053 duration, but different .006" advertised durations, the one with the longer advertised duration will have poorer idle vacuum and idle quality, and higher idle emissions too, than the modern grind. You don't even need a Cam Dr. for that comparison, its all on the cam cards!    TIMINATOR
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TIMINATOR

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Re: Why the lack of published cam specs
« Reply #30 on: June 23, 2018, 10:46:34 PM »

GRC: The severity of the opening/closing ramps in TCs relates more to Hydraulic Roller tappet limitations than cams. Oil aeration and lifter bleed down cause power loss and valvetrain noise. This is a big deal with larger Hyd. RLR cams in Big Block Chevies, as a heavy valve train and the required heavier spring pressures required cause lifter bleed down and noticeable power loss. This is why the popular 5.0 Ford engines respond well Horsepower wise with Hyd.Rlrs. and BBChevies don't. These issues are also why a drag car engine works better with a HYD. RLR. than a boat or other endurance engine. A drag car that runs only 10 second passes and then sits for a while does not heat or aerate the oil nearly as much as a Harley with hot aerated oil from miles of use. The other thing that I don't understand is why similar cams in HDs use 50 to 80 lbs. more seat pressure than a BBChevy engine. I have experimented with lighter than recommended spring pressure in HD engines with good results, but no explanations as to why from the cam companies. I expected Comp cams to explain their recommendations to me since they grind both auto and HD cams, but no info so far.
A BBC has a higher rocker ratio, bigger diameter and longer spring, heavier spring retainer, a similar length pushrod, bigger diameter and longer valve, and heavier locks than an HD, but less recommended spring pressure than the HDs for the same RPM range.

When I bought my 565" 14-71 blown and intercooled BBChevy powered boat, it came with a 260 degree @.050 and .670 lift Hydraulic Roller Comp. cam with 160 lbs. seat pressure as recommended from Comp Cams. RPM was 5300 and the boat ran high 90 MPHs. It had valve train noise above 4400 rpm (the lifters were bleeding down). I changed nothing but the lifters to solid rollers (different pushrod lengths were needed) and gained 450 rpm and 9 mph. I lashed the lifters at .004 intake and .005 exhaust. The valve train was a lot quieter too.

Bottom line: I run either short travel lifters or standard low bleed lifters and lash them up a half turn from the bottom with good results in my HDs, and never any signs of pump up. P.S lifter "pump up" (actually brought upon by valve float) was an old phenomenon from the old days when they didn't have computer designed and Spintron tested cam lobes and valve springs. Just some observations for comment from the TIMINATOR
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MCE

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We should publish
« Reply #31 on: June 23, 2018, 11:35:01 PM »

I wonder if we would get in any trouble for publishing the lobe profile data for HD cams...
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Nocvo

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Re: We should publish
« Reply #32 on: June 23, 2018, 11:36:11 PM »

I wonder if we would get in any trouble for publishing the lobe profile data for HD cams...
I'm guessing you would get a legal eagle phone call lol
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HD Street Performance

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Re: Why the lack of published cam specs
« Reply #33 on: June 24, 2018, 10:06:11 AM »

Why would there be any issue? And what significance and value would it bring to an average builder? I have stated what horsepower levels are currently. Over 20 years ago nightrider published horsepower expectations for modified street riden Harley bikes and what it would take to get there. The twin cam was nearly new and the prevalent engine was the EVO. They actually haven't changed a whole lot in all those years. We et al builders are building higher quality engines that last longer between overhauls however. We can give credit where due to the aftermarket and some to Harley as well as ingenuity. We now are at about 1.2 hp/cu in with 1.1 being more common and affordable. Will publishing the cams specifications help us move higher in horsepower levels normally aspirated on pump gas? Is the valve train, including the hydraulic roller lifters, the achilles heel that is holding horsepower back? On a similar but side note when testing a few of the cams you will find some tricks done that were done when I was a kid to win in stock class racing with cam profiles.
Quote from one of the manufacturers'
These cams get from .004" to .053" in only 32 degrees as our competitors cams get only from .020" to .053" in 36 degrees the result is better manifold vacuum, do to less non-advertised overlap also referred to By HARVEY J. CRANE as the cross over area so better engine acceleration thru the range.
This is in reference to opening, the closing is another story.
Makes power and is hell on parts.
Then you have S&S that designs and grinds their own cams. Industrial engine lobes by comparison.

So what are we going to do to bring these motors up while still remaining something you can put the wife on the back and ride cross country? That would help the OP and all Harley performance enthusiasts and more importantly the average guy, the ham and eggers, that just want to pass a truck on the freeway headed up a hill.
« Last Edit: June 24, 2018, 10:08:02 AM by HD Street Performance »
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MCE

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Re: Why the lack of published cam specs
« Reply #34 on: June 24, 2018, 11:08:55 AM »

I was thinking more about the serious performance engine guys. Jon Q Public wouldn't know what to do with any of it,
neither would allot of others. And why would they? (We already talked about that)

Quote
So what are we going to do to bring these motors up while still remaining something you can put the wife on the back and ride cross country?

Good question. Continuous R&D is what makes it possible. (Spending tons of time on the dyno, flow bench, (and simulators)).
The never ending pursuit of continuous improvement, It's just what some people do.
 
I'd like to have a database shared by like minded people so we could exchange/share data files. I have quite a collection
of them, but not as many as I'd like.
« Last Edit: June 24, 2018, 11:43:15 AM by MCE Performance »
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TIMINATOR

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Re: Why the lack of published cam specs
« Reply #35 on: June 24, 2018, 11:50:17 AM »

I don't see any legal issues with publishing raw data. We just wouldn't want to publish any of our conclusions as to the relative merits of certain designs. As per data only, would publishing the actual screen size of a laptop be any different?
In my experience looking at the shape of the lobes graph and digesting the quirk and jerk and acceleration rates is the more meaningful data to have. Its just not anything that Joe Average could do anything with. I feel that those that can use the data meaningfully probably have already spent the coin and have a cam analyzer, or are saving up for one...
As an alternative, graphing a lobe on a lathe between centers every 10 degrees or so will give a newbie the ability to at least get an idea as to what the differences are in the way a cam different cams act in their engine.
I started regrinding mini bike cams on my grandfathers lathe with a tool post grinder and a home made degree wheel when I was 14 or so, and that experience came in handy when I was running my street/ strip Chevelle years later. It ran high 10s at 124 mph with a Comp Cams street roller cam, and I wanted more. Long story short, I bought 5 "larger" cams from other manufacturers, all with 4 to 9 degrees longer duration at .050 and up to .075" more lift. All went slower, in ET and MPH. So I went back to the degree wheel/lathe for several evenings (it did take that long to get meaningful info) and discovered that every "larger" cam had less area under the curve. I called Comp. and bought another cam and went faster. Sold the other cams, destroyed a credit card and bought a Cam Dr. at the next PRI show. I still have it and use it regularly.
There are more than a few cam companies that produce laughable cams in area under the curve and quality, that are big sellers, because most cams are bought for "the sound," or the idea that "any power gain is more than I had." This is true of automotive and bike cams. Some people you just can't help.  Just more ramblings from the TIMINATOR
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MCE

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Re: Why the lack of published cam specs
« Reply #36 on: June 24, 2018, 12:10:26 PM »

Ha! Good points Tim. (I started out on single cylinder flat heads too, in the 60's).

I forgot to mention the track as a testing tool. That's the one that really counts.
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MCE

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Re: Why the lack of published cam specs
« Reply #37 on: June 24, 2018, 01:09:55 PM »

We had an engine shop class in high school. They had a small engine dyno that we tested the
Briggs, Kohlers and Tecumseh on. Blew up a bunch of them!
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TIMINATOR

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Re: Why the lack of published cam specs
« Reply #38 on: June 25, 2018, 11:14:24 AM »

I still play with mini bikes when time permits. Currently doing an 8HP OHV B&S motored Heald Super Bronc. Torq-a-verter drive, custom header (played with the formulas and re did it length and diameter 7 times), bored, flowed, and rejetted the carb, longer runner intake manifold, completely filled/reshaped intake runner, reshaped/filled exhaust runner, unshrouded combustion chamber, milled head, Cadillac NorthStar intake valve, V-6 Nissan exhaust valve,both the same stem size but cut down in length, 5+ angle valve job, advanced timing(made an offset crank key), indexed and side gapped spark plug, and whatever I forgot. Nothing at all done to the short block, never dissembled it, only top end. Original HP=7.8, new HP=15.9. STOCK CAM WITH STOCK PHASING (so far). Old top speed=34, new top speed=63+. I have a cop RADAR gun.
Sometimes its easier to try things on a single cylinder, or a 4 cyl. 2000 Pinto engine. You can learn something on anything...  I taught myself porting with a 2300 Pinto engine, Dykem layout fluid and spray paint. Where the air goes, so does the fuel, fuel removes Dykem, Exhaust burns paint, where the exhaust goes, no paint. I figured that out when I was very young and couldn't afford a flow bench. Paint/Dykem the ports, make a full throttle blast down the street, remove head grind/reshape the clean spots. By the time I made an industrial shop vac flow bench, I had a reasonable idea how air worked. The Superflow 600 came later...
Study steam engines if you want to understand compression(expansion) ratio effects. Study Boyle, Hooke, Gay-Lussac and Hilsch if you want to learn about air. The Super Flow tells you what happened, studying the pioneers tells you why.  TIMINATOR     P.S. later I'll clue y'all in on my other mini bike project.
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TIMINATOR

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Re: Why the lack of published cam specs
« Reply #39 on: June 25, 2018, 11:51:25 AM »

Sorry about the long winded post, but in conclusion: If you don't publish cam specs, maybe you aren't grinding your own cams, or are just copying someone elses lobes, and mebbie using different intake lobes form one guys cam and an exhaust lobe from someone else's cam. Maybe you don't really understand what it is you are doing, so you can't really have a good discussion about it. Or perhaps you really think that you have re-invented the wheel and have discovered a "secret" grind that works perfectly in everything. The proof is on the street and on the dyno. Not in the advertising. A while back a company advertised: "The Worlds Most Powerful XXX Cam." It did make a bit more power than the other XXX cams, but for those of us with a way to analyze cams, we knew that it was actually a longer duration than an XXX cam, and also had more lift than advertised, and that's why you needed their "Special" valve springs.
I AM NOT POINTING A FINGER AT ANY COMPANIES HERE NEW OR OLD!!!!!  Just relating what went on in the automotive Cam Wars of the 1970s.
"Those who do not study History are doomed to repeat it." I don't remember who said that, but I know its true.   

Boy, I probably started something here!         TIMINATOR

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TIMINATOR

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Re: Why the lack of published cam specs
« Reply #40 on: June 25, 2018, 11:56:27 AM »

P.S. My Grandma said: "If the truth hurts, it probably should."     TIMINATOR
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MCE

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Re: Why the lack of published cam specs
« Reply #41 on: June 25, 2018, 12:03:12 PM »

I had to take allot of those M.E. classes, (even though I majored in Electronics).

I've forgotten most of the math formulas (it's been 40 years) but the concepts
are still up there. And I read allot too.
« Last Edit: June 25, 2018, 12:23:29 PM by MCE Performance »
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MCE

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Re: Why the lack of published cam specs
« Reply #42 on: June 25, 2018, 04:06:29 PM »

We didn't have access to computers like we have now, when I went to school. (If you needed a computer for an assignment,
you had to schedule it and fight over time slots.)
 
Now days, with the computing power that's available and the simulator programs, just about anyone can attempt to design
whatever they want. It's so damn amazing how far things have come. It just blows my mind to think what will be available
in another 20-30 years.

Advances in metallurgy and computing power are what's driving the advances and the power we're able to get out of these
engines.
« Last Edit: June 25, 2018, 04:16:56 PM by MCE Performance »
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TIMINATOR

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Re: Why the lack of published cam specs
« Reply #43 on: June 26, 2018, 11:29:41 AM »

Another reason for no cam specs: The company just signed up with a large supplier of cams that are all the same as a lot of other "Private name" cams. If they published the specs then all would know that they sell the same generic stuff as others. In the automotive industry, Elgin grinds the house brand cams for many distributors. I believe that at least one company still advertises on their own web site that they will grind, box, and label your "house brand " cams. Google 204/214, 222/222, 214/224 duration automotive cams for instance and see how many brands you come up with. Some companies actually mis label the cams by a degree or two and a few thousandths lift to mislead you. Those generic cams have been sold since the 1970s and are of ancient designs, but they are useful to some because they will still make more power than a stock cam, and are cheap. Not to say that nobody else actually grinds their own cams to that spec. but if it looks like a duck, walks and quacks like a duck, mebbie it just might be a duck. Especially if most of the ducks look the same and are cheep (pun intended).
Then there are a few automotive companies that buy the old "master" lobes that were used on old manual cam grinding machines when the original companies sell them off cheap (because the "master" is worn and no longer grinds what was originally intended.) Some of them Cam Dr. the resulting lobes and then advertise the cam as what it actually grinds to now, problem is that the ramps are no longer the shape that was originally intended (valve float? or just less area under the curve?)
Another company comes to mind. This guy Cam Drs, the lobes to compute the area under the curve, then sells the cams as a shorter advertised duration like a modern cam so his old cams seem to make as much top end power as newer fast ramp designs. Idle quality is worse and they come up on the power band later, but can make the same power up top. I became aware of that practice in about 1990 when I built a set of BBChevy competition heads for a customer. I supplied Comp Cams springs, retainers and locks, and set them up for the cam as indicated on the cam card he had. I tried to talk him into a Comp Cam too, but he "went to school in California with this guy and he bought the cam really cheap because they had History." The heads sat until about 6 months later when he had the cash for the short block, he assenbled it, drove it on the street for a few weeks and took it to the dragstrip and bent every exhaust pushrod. After listenening him scream about my incompetance for about an hour, he brought over the heads. I pulled out a copy of his cam card and checked the clearances as stated on the card, they were fine. More screaming. I went with him to his garage and removed the cam myself, came back and Cam Doctored it. Intake and exhaust durations were 5 to 7 degrees longer and exhaust lift was almost .05 something higher. The cam was marked the same as the cam card. No apology. He did make excuses and the guy sent him another cam, it measured the same. He blamed my Cam Dr. We checked about a half dozen of other cams I had laying around, and all the others were fine. No apology still. I never did any more work for him again. But after hearing stories from others, I posted a large blown up copy of the cam card and the Cam Dr. results along with his name and date. He sued me for slander. I won. I left that info on the wall for about 15 years, along with a copy of the the court judgement!
I Cam Dr. every cam I install since, and refuse to install one every once in a while.
Sorry for the long rant, but it might save someone a bit of grief.  TIMINATOR   :soapbox:
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remington007

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Re: Why the lack of published cam specs
« Reply #44 on: June 28, 2018, 02:22:49 PM »

I had a interesting thing happen on my shovelhead last winter. I have been running a Andrews #2 in my 87 inch stroker and i had a starting issue from compression. So in the general world i thought to just add a cam that the intake closes later, problem solved. So i went from a #2 that closed a 35* to a V-Thunder 4010 that closed at 42*, 7 degrees later should help right?  Instead it raised the compression 10 lbs. So i would guess something below 53* advertised timing does affect things. 
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TIMINATOR

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Re: Why the lack of published cam specs
« Reply #45 on: June 29, 2018, 03:14:46 AM »

Seat to seat timing means more to cranking compression than .053 timing, also, did you check both of the cams degreeing? It too may vary and cause your symptoms. Or a combination of both. Andrews cams typically have lazier ramps than the V-Thunder cams too. Same deal. Briggs & Stratton "easy spin" starting cams use a late intake closing of seat timing to effect lower cranking compression. Once started, the long slow intake closing ramp means less to the running power band. Outboard motors in the old days before electric start also used the same method, as the early Evenrude/ Johnson "performance" engines (28 and 35 HP) started to use higher compression to make more power. Prior to this they were a mother bear to start. They were 2 stroke engines, but the same principle was applied to cylinder porting.  TIMINATOR
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