cam "blue printing"
- Thread starter Ed Funk
- Start date
lateapex911
Super Moderator
It's been done. But, you (the protester or the protestee) don't send the 'stock cam'. For evidence purity reasons, a third party procures that. SCCA has some cams on digital file. They source the rest, then send them back.
I don't know what the Cam Doctor uses as a pass/fail threshold, but I imagine it will catch things like the ITB BMW 2002 cams I read an ad for that called them "IT tech shed legal cheater cams".
As to enforceable at a local event, I'd imagine that if it had excessive lift, it would be dinked right away. Measuring cams is something that (I bet) tech would get a bit bnervous about. If I had reasons to think that I needed to protest somebody over a cam, I would:
-find a tech guy I know and discuss it quietly, then..
-inform the tech staff that would be attending that event to be prepared for such a protest. That part would make me nervous, as it presents a chance for info to leak, but I think things would go smother with that approach.
In any case, I'd be prepared to have the cam impounded and sent to Topeka. Also, out of fairness to the protestee, I might plan on doing such a protest when there wasn't an event the next weekend, so as to not disable his car and preclude him from racing. (See spiteful Spec Miata protest fiascos of years past as examples of such 'strategies')
I don't know what the Cam Doctor uses as a pass/fail threshold, but I imagine it will catch things like the ITB BMW 2002 cams I read an ad for that called them "IT tech shed legal cheater cams".
As to enforceable at a local event, I'd imagine that if it had excessive lift, it would be dinked right away. Measuring cams is something that (I bet) tech would get a bit bnervous about. If I had reasons to think that I needed to protest somebody over a cam, I would:
-find a tech guy I know and discuss it quietly, then..
-inform the tech staff that would be attending that event to be prepared for such a protest. That part would make me nervous, as it presents a chance for info to leak, but I think things would go smother with that approach.
In any case, I'd be prepared to have the cam impounded and sent to Topeka. Also, out of fairness to the protestee, I might plan on doing such a protest when there wasn't an event the next weekend, so as to not disable his car and preclude him from racing. (See spiteful Spec Miata protest fiascos of years past as examples of such 'strategies')
Last edited:
it's been done in this division.
Measuring cams is not difficult, if you have the specs. In fact, macro checks of the lift can be done with hand tools (not to the level to get bounced - you need specs, v-blocks, and a dial-indicator setup for that - but certainly adequately enough to check for gross cheating). But the only real way to do it per the GCR is to send them to Topeka with the (now, lower) test fee (non-refundable).
Jake, you're mistaken: the GCR actually requires the protester to provide a "known stock example" of the part(s) being protested. In the past, that's generally meant the protester has the part(s) sent directly to the inspector(s) from a trusted third party. Topeka does have camshaft profiles of common cars, but don't count on them having one for a Suzuki Swift <...rubbing hands/evil grin...>
Don't worry about the "word getting out"; once a protest is filed against a competitor, the car is immediately impounded, and their failure to allow inspection (or impound) results in immediate Steward action. - GA
Jake, you're mistaken: the GCR actually requires the protester to provide a "known stock example" of the part(s) being protested. In the past, that's generally meant the protester has the part(s) sent directly to the inspector(s) from a trusted third party. Topeka does have camshaft profiles of common cars, but don't count on them having one for a Suzuki Swift <...rubbing hands/evil grin...>
Don't worry about the "word getting out"; once a protest is filed against a competitor, the car is immediately impounded, and their failure to allow inspection (or impound) results in immediate Steward action. - GA
Last edited:
lateapex911
Super Moderator
Greg, I hear you, but...what I meant was that the protester provides the means to get the "Known stock example". If I showed up with a Honda/Nisaan/Mazda etc cam in a bag and handed to to you and said, "here is the stock version" it would be rejected, as you would have to assume I had some trick up the sleeve....it's an obvious conflict of interest.
But in the protest, I provide the means for others (unbiased third parties , ie, Stewards) to do the legwork, right?
I was told (by Tech) when I did a similar protest, that I should have contacted tech a week or so in advance, so that they would be prepared. As it turned out, they were most certainly NOT prepared (search this site for "A Protest Story" for a detailed rundown of how that played out) for what I had thought was a semi do-able protest. The concern going in was that leaking word that far in advance might yield adverse results. (That and the fact that the group of guys made the final call the morning of the actual protest...and we decided "By the book" was the way to go)
Heck, in that protest, the tech guys called out asking for tools to do the protest. We offered tools, but were rejected on teh conflict of interest basis.
But in the protest, I provide the means for others (unbiased third parties , ie, Stewards) to do the legwork, right?
I was told (by Tech) when I did a similar protest, that I should have contacted tech a week or so in advance, so that they would be prepared. As it turned out, they were most certainly NOT prepared (search this site for "A Protest Story" for a detailed rundown of how that played out) for what I had thought was a semi do-able protest. The concern going in was that leaking word that far in advance might yield adverse results. (That and the fact that the group of guys made the final call the morning of the actual protest...and we decided "By the book" was the way to go)
Heck, in that protest, the tech guys called out asking for tools to do the protest. We offered tools, but were rejected on teh conflict of interest basis.
A cam's duration is not a simple matter of measuring the base circle and subtracting that from the lobe measurement (thus my allusion above to "gross" cheating); cams' measurements are typical to and from a certain degree, and/or height between specific valve lift ('lash'). So, to measure lift correctly you need v-blocks (to spin the cam on), dial calipers (to measure the starting/ending point and the total lift), and specs ('cam card'). The Cam Doctor does all this for you. It'll "create" a cam card electronically if you measure a known stock example, then you compare that data to the part in question.
An alternative is to use an optical comparator, which projects the profile of the cam visually over a known shape. From there you actually compare the shape/profile.
To answer your question directly: yes, a known stock example is needed, assuming you don't have the Cam Doctor or optical comparator info already.
Oh, I'm well aware and remember it well. Everything that COULD have been done incorrectly WAS. However, I'd like to think that your experience is not indicative of how the process would work as a matter of course...I know it's not the way I would have handled it.
The few factory service manuals that I have seen don't list cam specs, tho you can usually extrapolate lift, but duration etc ---fugidabotit!
lateapex911
Super Moderator
I've sometimes wondered if your increased role in the tech dept was in part due to your observance of the proceedings. Certain the release of the questionable parts that hadn't been determined to be legal/not legal was a huge shock to me, and I had a hard time following Dick Patullos first rule of screw ups, to wit: "Assume stupidity before malice"......
Addendum, for simplicity: you can do the same thing a Cam Doctor does. All you need are a couple of v-blocks, a degree wheel (I've got one), a dial-indicator (ditto), and a dial-indicator magnetic base (or some kind of fixture - ditto).
Drop the known stock cam into the v-blocks. Attach the degree wheel to the end of the camshaft with the wheel's TDC at the cam's TDC mark (or any suitable "zero" point such as the center of the pin/keyway). Zero the dial indicator on the base circle at TDC. Slowly rotate the cam 1 degree at a time and note the dial indicator's reading. Do this 359 more times and you have the cam's profile; toss it into an Excel spreadsheet and you can even chart the profile graphically. Do the same thing for the camshaft in question and compare the data; it will give you lift (is the total lift different?), duration (has the duration been changed?), profile (is the lift and duration the same, but the cam's been changed in between?), and pin location data comparisons (has the pin been moved to change timing?)
Any technically-competent person should be able to do this, but this is what the Cam Doctor does for you, without having to know how to use the above tools.
Now, would a protested competitor settle for this method? Probably not. And, does the majority of SCCA Regional/Divisional technical staff have these tools and technical abilities? Probably not. Thus, SCCA bought a Cam Doctor and performs the service for you (and retains database info about various cams). - GA
On edit:
Drop the known stock cam into the v-blocks. Attach the degree wheel to the end of the camshaft with the wheel's TDC at the cam's TDC mark (or any suitable "zero" point such as the center of the pin/keyway). Zero the dial indicator on the base circle at TDC. Slowly rotate the cam 1 degree at a time and note the dial indicator's reading. Do this 359 more times and you have the cam's profile; toss it into an Excel spreadsheet and you can even chart the profile graphically. Do the same thing for the camshaft in question and compare the data; it will give you lift (is the total lift different?), duration (has the duration been changed?), profile (is the lift and duration the same, but the cam's been changed in between?), and pin location data comparisons (has the pin been moved to change timing?)
Any technically-competent person should be able to do this, but this is what the Cam Doctor does for you, without having to know how to use the above tools.
Now, would a protested competitor settle for this method? Probably not. And, does the majority of SCCA Regional/Divisional technical staff have these tools and technical abilities? Probably not. Thus, SCCA bought a Cam Doctor and performs the service for you (and retains database info about various cams). - GA
On edit:
Absolutely. Two major things happened to motivate me; that was one of them.
Andy Bettencourt
Super Moderator
Ahhh, the beauty of running a Miata. All the cam specs are on file in Topeka. They could turn that protest around quick!
Z3_GoCar
New member
Sure you've got a profile of one cam that's stock and one from the motor, but what's the manufacturing tolerance? How much variation between stock cams, and are you really sure it's within that level? I know of a company that makes a "stock" cam for rules similar to IT for their factory racing efforts, only the cam's take advantage of their manufacturing tolerances. I'm reminded of the SM protest where they measure the sway bar and said it was the wrong size but didn't account for the layer of paint on the bar
Far, far less than what is required to make a performance difference.
That's what we here call "cheating"
I don't know of whom you speak, but I strongly suspect it's built less to "manufacturing tolerances" (cams are ground to pretty precise tolerances, even mass-produced ones) and more to "it'll meet the measurements at the points where it's typically measured, and everything else in between is pretty wacky."Thus, the Cam Doctor.
Hmmm Ed you're asking all of these cam questions Ya nervous or something?
---or something!!!
lateapex911
Super Moderator
If you want to provide those extra cams as "proof" don't bother. What's to stop a protester from providing "Stock" cams that aren't?
If you think YOU'RE going to be the protestee, then by all means, now you're back in business while the cams are out to the Good Doctor.
I have heard.. not going to mention from whom.. but they got stock cams from supplier A.. then drilled there own dowl pin at the at teh degree that they found most beneificial within the stock range. Fortuantely for them the stock cams range was apparently failry broad. A fair stretch of the rules that if jsut left up to a degree wheel and dial gauge would be legal. The cams got protested, however the protested party was handed the portest then told to bring there car up tech. Since the messenger left, they were able to swap in stock cams before having to pull them again in tech. (there was a reason why the car didn't run to the tech shed.. the timing was WAY off.. they jsut threw the cams in there.. didn't have time set them up.)
Side note.. As a vote of relief this was not on a IT car.
Side note.. As a vote of relief this was not on a IT car.
lateapex911
Super Moderator
Far, far less than what is required to make a performance difference.
That's what we here call "cheating"
Thus, the Cam Doctor.
Bingo. And this is something to be aware of when writing a cam protest. If you decide, for whatever reason, to protest a guys cams, and you only list factory specs (lets say that's only duration and say lift) you are leaving a lot of other points on the table. You might get the results back that the cam meets specs and is "legal" when in reality, it isn't close to stock.
If you really think a guy is cheating, then you might want to assume he's smart enough to really cheat. Send the cam off to Topeka for a complete profile check against a known stock version. If you are going to kill the king....kill the king.
(If you think he's kinda cheating, like he's got the wrong cam in there because he's running a wrong assumption or by accident, then a paddock chat might be the way to go)
I'm just a dumb rotary guy, but even I know there's a lot that can happen between start of open, full lift and close.
lateapex911
Super Moderator
CRASH! Steward totally dropped the ball, huge misconduct. Totally against the book. Once the evidence is out of the control of the stewards, it's tarnished and the whole deal is screwed. The protester should have written the Steward up.