Flyinglizard
New member
What is the max cam retard that would be considered legal?
cam timing?
- Thread starter Flyinglizard
- Start date
wrong. stock CAM timing, or timing within the demonstrable tolerances of stock, or as resulting from the compression-increasing cut as Chris said. if you mean spark timing, well, yeah, more or less you are correct but Mike asked about CAM timing.
dril and pin the cam where you want it, use of allowed stepped keys or offset bushings to set timing to a position OTHER than stock or maybe between stock and the landing point after compression cut, etc... is NOT what the ITCS says. just having stock gears does not make the motor legal.
mike, buy my book: http://www.scca.com/documents/2011 Tech/GCR- updated July.pdf
shwah
New member
ORLY?
Please point us to the ITCS reference that allows changing cam timing in any way other than:
1. using factory installed variable cam system & allowed ecu modification
2. allowed increase in compression by removing material from head/block, changing cam timing in OHC motors.
3. allowed offset key to return cam timing to stock in case #2.
Flyinglizard
New member
The SM has the only cam time specs.
The rule states ; cam maybe returned to stock timng with offset key. The cam can get 5or 6 degrees late with a head cut. I like to run my VW @ about 3 late.
Adjustable cam wheels, make a lot of sense, cheaper, faster than messing with a degree wheel and offset keys.
The rule states ; cam maybe returned to stock timng with offset key. The cam can get 5or 6 degrees late with a head cut. I like to run my VW @ about 3 late.
Adjustable cam wheels, make a lot of sense, cheaper, faster than messing with a degree wheel and offset keys.
Doesn't matter what you like, and what SM is/are doing. look into your factory service manual and see what they spec out. If you are anything other than than you are illegal. typically a service manual will have the spec'ed value and a acceptable range. Dependong on configuration and the amount of cams.. DOHC is restricted to offset keys (What a pia) but is the only option. SOHC are allowed to use offset bushings, which are cheap and easy to setup. Kinda wish I could do that on my DOHC setup, but I can see why they don't want to do that to prevent changing in cam phasing from stock. Atleast I think that was the point of the rule?
Eagle7
New member
Me too
Flyinglizard
New member
I think that the VW goes about 2.2 degrees per 010 head cut.
The short answer says ." no spec".
The book has no spec other than the min head thickness.
Thanks for all of the answers. No spec is no spec. We are getting ready to run the old ITB car hard again.
The short answer says ." no spec".
The book has no spec other than the min head thickness.
Thanks for all of the answers. No spec is no spec. We are getting ready to run the old ITB car hard again.
Ron Earp
Administrator
I've got no specifications in my 1998 Ford Mustang shop manual for cam timing. Modern manuals are a lot different than older manuals, such as what I had with my 70s Datsun. Nowadays R&R is all a shop manual is about. The intent of the IT rule is for you to run the cam timing in the factory configuration.
Are people with no specs really going to run whatever the hell they want?
Are people with no specs really going to run whatever the hell they want?
That there is no PUBLISHED SPEC IN ONE PARTICULAR BOOK absolutely does NOT mean that there is NO SPEC. One can play "tech-shed legal" all he wants but the minute someone shows that what he got ain't stock, he's a cheater.
K
rcc85
New member
My interpretation has been that your legal options are:
1. Unshaved head with non-offset key - stock cam timing
2. Shaved head with non-offset key - whatever cam timing that turns out to be
3. Shaved head with offset key that returns the cam timing to stock.
I don't believe that you can place the cam timing between options 2 and 3 with the use of offset keys.
Also, don't most cars with stock cams make more horsepower (but less torque)with the cam retarded? I know on the 2.2's, Chrysler cut the block on the Shelbys to increase compression which retarded the cam timing and they intentionally left it there (as noted in the FSM).
Bob Clifton
#05 ITB Dodge Daytona
1. Unshaved head with non-offset key - stock cam timing
2. Shaved head with non-offset key - whatever cam timing that turns out to be
3. Shaved head with offset key that returns the cam timing to stock.
I don't believe that you can place the cam timing between options 2 and 3 with the use of offset keys.
Also, don't most cars with stock cams make more horsepower (but less torque)with the cam retarded? I know on the 2.2's, Chrysler cut the block on the Shelbys to increase compression which retarded the cam timing and they intentionally left it there (as noted in the FSM).
Bob Clifton
#05 ITB Dodge Daytona
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Gary L
New member
I think it will vary depending on the engine/cam. I've seen cheater Volvo engines with offset keys that put 5 or 6 degrees of timing advance in the cam.
Z3_GoCar
New member
For some of us advanced cam timing is a matter of flipping a solenoid on.
That said, my manual doesn't have spec's on cam timming. But, it does have a proceedure for setting it. If the proceedure is followed, and the cams don't line up...
well it's clearly not an area that can be played in to optimize power gain, per the ITCS.
That said, my manual doesn't have spec's on cam timming. But, it does have a proceedure for setting it. If the proceedure is followed, and the cams don't line up...
well it's clearly not an area that can be played in to optimize power gain, per the ITCS.
Flyinglizard
New member
Bob has the IT facts ,per rules.
The tech side is that the cam needs to be near center to make power. Any more than 5* either, way will go slower. Different venues might have different optimal cam timing specs. The oval tracker makes the same lap times withthe cam straight up or set back 4 *. The exit RPM( 4800) is better wi th the cam ahead a little. (thus creating passing oportunities).
For Road racing,if the car wont pull gear, maybe retarding it will alllow a little higher revs. IE Daytona with a 20 sec high gear pull. Sebring, with the stop and pulls, might like it ahead 3*.
FWIW, lack of spec also means lack of protest power. Some one would need a valid cam opening/ closing value to have a valid protest. Without the factory numbers, any value other than a line in the spec line would be suspect. The way the rule is written, there cannot be a protest over the cam timing.
The rules are fine as written in this respect. I have built the Volvos with the cheater cams that where deamed legal, when clearly they were meant to use all of the cam timing available. ( and well outside of the spirit of the rules.) Any Volvo that runs to 7400rpm, has the wrong valve springs, the wrong cam, etc. The same as any Mk 3 VW. IMHO..
MM
The tech side is that the cam needs to be near center to make power. Any more than 5* either, way will go slower. Different venues might have different optimal cam timing specs. The oval tracker makes the same lap times withthe cam straight up or set back 4 *. The exit RPM( 4800) is better wi th the cam ahead a little. (thus creating passing oportunities).
For Road racing,if the car wont pull gear, maybe retarding it will alllow a little higher revs. IE Daytona with a 20 sec high gear pull. Sebring, with the stop and pulls, might like it ahead 3*.
FWIW, lack of spec also means lack of protest power. Some one would need a valid cam opening/ closing value to have a valid protest. Without the factory numbers, any value other than a line in the spec line would be suspect. The way the rule is written, there cannot be a protest over the cam timing.
The rules are fine as written in this respect. I have built the Volvos with the cheater cams that where deamed legal, when clearly they were meant to use all of the cam timing available. ( and well outside of the spirit of the rules.) Any Volvo that runs to 7400rpm, has the wrong valve springs, the wrong cam, etc. The same as any Mk 3 VW. IMHO..
MM
shwah
New member
The factory's consumer manual is not the only valid source for specs to confirm legality.
I have heard a lot of folks talk over the years about IT in FL being more loose with rules than in other places. I have no reason to think they are, or are not, but if that is the case, I would hope that someone trying to go fast (i.e. go to the IT Fest or ARRC and compete) would make sure their program was legally acceptable to the letter of the ITCS, rather than to the level of what locals are willing to complain about.
This is amateur racing. For fun. Folks that intentionally do stuff that are outside the rules don't get it, and are part of "the problem", even if there is no way to get caught. It sounds like some of your past clients may have been those types. I'm glad that you are a lot more open and up front about trying to find the legitimate line between inside and outside the rules. Hopefully you guys are still running the B car hard by the time I can get back to a more full schedule (even though at time that feels like never!!), and we can get to RAtl or somewhere together.
I have heard a lot of folks talk over the years about IT in FL being more loose with rules than in other places. I have no reason to think they are, or are not, but if that is the case, I would hope that someone trying to go fast (i.e. go to the IT Fest or ARRC and compete) would make sure their program was legally acceptable to the letter of the ITCS, rather than to the level of what locals are willing to complain about.
This is amateur racing. For fun. Folks that intentionally do stuff that are outside the rules don't get it, and are part of "the problem", even if there is no way to get caught. It sounds like some of your past clients may have been those types. I'm glad that you are a lot more open and up front about trying to find the legitimate line between inside and outside the rules. Hopefully you guys are still running the B car hard by the time I can get back to a more full schedule (even though at time that feels like never!!), and we can get to RAtl or somewhere together.