Cam Timing

[Bill Miller]

100!

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608

[Quickshoe]

Originally posted by apr67:
Darrin. Would it be legal in It for me to put a motor together with the timing off a tooth? I can't think of many motors that would benefit from this, but who knows?

Actually laughed out loud on that one. No "LOL" a real laugh that I had trouble holding in. Nothing like tossing a little gasoline on a still smoldering fire...

[Geo]

Originally posted by apr67:
Darrin. Would it be legal in It for me to put a motor together with the timing off a tooth? I can't think of many motors that would benefit from this, but who knows?

Knock yourself out.


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George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com

[eh_tony!!!]

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Originally posted by lateapex911:
And.....Geo, I bet YOU a Shiner Bock that YOUR letter asking for cam timing clarification comes back as "Adjustable cam gears that were fitted as stock shall be set to factory specs"....AND that the rule book gets the word "may" changed to "shall" with the other explanatory language next year.
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I'm in for a 6 pack that the CB's response will be the standard "rules are adequate as written" with no additional clarification of leglity/illegality.

My opinion here is that adjusting cam timing is perfectly legal. You may want to shave the head a bit though to support my side of the argument. (so use some 1000 grit wet dry and shave of .00000001 mm.

The GCR says that you are allowed to shave the head, we all agree on that. I believe we all agree as well that the GCR says that we MAY use an offset key to return cam timing to stock. I think also everyone is in agreement that we do not HAVE to use an offset key to return cam timing to stock.

This opens the door to out of FSM cam timing. so, since the GCR does not further define any limitations on that "out of stock" condition, I consider it free.

[eh_tony!!!]

Here's another one I was thinking about over some lagers... (at least for 1 of the 2 cams). If ignition timing is free and the distributor is driven off a cam gear, what's to say you can't adjust the ignition timing by changing the cam/crank relationship? I'd love to hear responses on this one

[Ron Earp]

Nice one. Too bad it took over 100 posts to get a good answer.

I just went out and shaved my head. I rubbed it with some emory paper. I think I saw some aluminum on the paper.

I may return the cams to the stock timing setting. I may not.

Ron

[This message has been edited by rlearp (edited September 26, 2004).]

[Greg Amy]

<font face=\"Verdana, Arial\" size=\"2\">...GCR says that we MAY use an offset key...this opens the door to out of FSM cam timing...</font>

Hmmmmmm.....huh...mmmm.....you know, you might have me convinced with this line of logic...on one condition:

*IF* we accept that this opens the door to out-of-FSM cam timing, is this out-of-specness limited to only one direction to o to only shaved heads? IOW, if "out of FSM" cam timing is allowed as per your argument (let's say, with a .0000001 shaving), can I then optimize my cam timing to where I want it, plus *or* minus? Further, since cam timing is now open, can I use offset keys to *only* put the cam into FSM specs or can I use them to optimize my power band?

If not, why not?

If you suggest that *if* I use offset keys I can *only* change the cam timing to FSM spec timing, then I must defer back to my original position; to do otherwise would offer a different modification level to different cars and I do not believe this is the intent of the rule. If, however, "the door" to non-FSM cam timing is truly open as you say, then there's nothing stopping me from optimizing cam timing to my performance advantage.

(P.S. I do still believe that the intent of the rule is for camshafts to be timed to FSM specs, but I am willing to accept the logic of this truck-sized loophole in the spirit of Motec and spherical bearings, if applied evenly to all cars).

Thoughts?

[eh_tony!!!]

*IF* we accept that this opens the door to out-of-FSM cam timing, is this out-of-specness limited to only one direction to o to only shaved heads?
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My read would be that 'out of spec' is out of spec. a good argument could be made for direction, but IMHO without a re-word it does not apply. But yes, it is limited to shaved heads
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IOW, if "out of FSM" cam timing is allowed as per your argument (let's say, with a .0000001 shaving), can I then optimize my cam timing to where I want it, plus *or* minus? Further, since cam timing is now open, can I use offset keys to *only* put the cam into FSM specs or can I use them to optimize my power band?
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Offset keys could only return it to FSM. Since no other means exists to modify/change pully's, the LOTUS is prolly the only car that can use this to advantage)
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If not, why not?

If you suggest that *if* I use offset keys I can *only* change the cam timing to FSM spec timing, then I must defer back to my original position; to do otherwise would offer a different modification level to different cars and I do not believe this is the intent of the rule. If, however, "the door" to non-FSM cam timing is truly open as you say, then there's nothing stopping me from optimizing cam timing to my performance advantage.

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I agree completely with that paragraph




[This message has been edited by eh_tony!!! (edited September 26, 2004).]

[Ron Earp]

Originally posted by eh_tony!!!:

(P.S. I do still believe that the intent of the rule is for camshafts to be timed to FSM specs, but I am willing to accept the logic of this truck-sized loophole in the spirit of Motec and spherical bearings, if applied evenly to all cars).

Thoughts?

No doubt. This thread was started by me asking if it was okay to use my factory provided adjustable timing gears. If a BMW owner can replace an entirely factory ECU with an aftermarket dedicated race unit, then this topic is a drop in the bucket.




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Ron
http://www.gt40s.com
Lotus Turbo Esprit
BMW E36 M3
RF GT40 Replica
Jensen-Healey: IT prep progressing!

[lateapex911]

Originally posted by eh_tony!!!:

The GCR says that you are allowed to shave the head, we all agree on that. I believe we all agree as well that the GCR says that we MAY use an offset key to return cam timing to stock. I think also everyone is in agreement that we do not HAVE to use an offset key to return cam timing to stock.

Yes to shaving, Yes to "May" use a key, NO to the "we do not have to" part.

I see the logic flow, BUT in the bigger picture, what if the rule reminded you that you could use the offset key or the adjustable cam gears if your car is so equipped?

<font face=\"Verdana, Arial\" size=\"2\"> This opens the door to out of FSM cam timing. so, since the GCR does not further define any limitations on that \"out of stock\" condition, I consider it free.</font>

It does "open the door" if you ignore the larger picture and the basic IIDSYCYYC premise.

So, nowhere does it say "cam timing is free", it says you can retain your adjustable gears if they came stock, and it says you may use an offset key key to acheive correct timing. So, lets put the Shiner Bocks on the table, boys!

Again, I feel the rule is subject to a little extra light for us to see it correctly.


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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[This message has been edited by lateapex911 (edited September 26, 2004).]

[Eagle7]

I still think the analogy to front toe setting is appropriate. I've not found anywhere in the GCR where it addressses this adjustment allowing non FSM settings for front toe. Can someone reference specific paragraphs if it is there? I think if you've got a factory supplied adjustment, you can adjust it.

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Marty Doane
ITS RX-7 #13
CenDiv WMR

[eh_tony!!!]

Originally posted by lateapex911:

Yes to shaving, Yes to "May" use a key, NO to the "we do not have to" part.


ok, ok, what I meant to say was not that "we don't have to use an offset key to move cam timing back to stock", rather I meant "We do not HAVE to move cam timing back to FSM" In my opinion, the rule was written to say basically, "if you would like to move your cam timing back to stock, you may use an offset key"


I see the logic flow, BUT in the bigger picture, what if the rule reminded you that you could use the offset key or the adjustable cam gears if your car is so equipped?

It does "open the door" if you ignore the larger picture and the basic IIDSYCYYC premise.

Larger picture?? How so? You can't argue that there are no cars in IT with adjustable cam timing, hell there are even electronicallly actuated adjustable.

The IIDSxxxxx premise of course only holds true if it does not say you can. Here the GCR plainly says that you can have a car whose engine camshaft timing differs from what was stock.

[/B][/QUOTE]

I'll give you an example of a rules clarification I requested.

My old Fiat has a wishbone axle locaing system. If you read the GCR, the GCR says Panhard rod or Watts link. I aske for a wording change to include wishbone. The response from the CB is that the present wording is sufficient to allow the wishbone. (it's in fastrack a few months back)

BTW if one is going to so stricktly interpret the IIDwhatever rule, there wouldn't be a legal car in the field. I'm sure I could go through and find things like out-of-spec torque settings on various fasteners like lug nuts, etc. The GCR says you may change fasteners, but it does not say they may be torqued to anything other than factory specs.

[lateapex911]

The crux as I see it is in cases where adjustments away from the FSM result in performance changes, the allowance is called out, eg: ignition timing.

Does the torque of my fender fastener affect my performance?

The ITCS goes out of its way to call for stock timing when replacing gears, and also requires that the relationship between intake and exhaust be maintained by placing the offset key on the crank, so they have created precedence in those requirements.

The lack of an allowance and the basic IIDSYCTYC premise, along with the basic "either/or" logic of key OR adjustable gears, has me thiking its not legal.

I will be very interested in the outcome of the clarification.

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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[Geo]

Guys, I submit that some of you are taking a variety of specific cases in the ITCS and are trying to apply them to another case to draw a conclusion that is simply not there.

Rule:

The rules say you can replace phenolic/plastic gears with metal gears. Cam timing must remain stock.

This rule is complete. No other wording is required (OK if someone has phenolic adjustable gears I guess we'd really potentially ahve a mess). But a specific situation is covered with a clear rule.

Rule:

You may shave the cylinder head. If you do, you may use an offset key to return cam timing to stock.

This rule is also complete. You have the option of using the offset key to return cam timing to stock. There is no provision for using the offset key to use any other cam timing. But the use of an offset key would be optional. A specific situation is covered with a clear rule.

Rule:

If a car is fitted from the factory with adjustable cam gears they may be used. There is no limit placed upon the range of adjustment that can be used. This specific situation is somewhat less clear. I say use what you've got. There is no place in the rules to limit this adjustment and adjustable gears are explicitly allowed if they are factory equipment.

No where in the GCR or ITCS that I remember requires any component that is adjustable to only be adjusted within the stock specs. All limitations appear to be to be placed upon parts, not adjustments.

Intent? Intent insment. What do the rules actually say?


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George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com

[Quickshoe]

Originally posted by eh_tony!!!:
If ignition timing is free and the distributor is driven off a cam gear, what's to say you can't adjust the ignition timing by changing the cam/crank relationship? I'd love to hear responses on this one

"...no permitted component/modification shall additionally perform a prohibited function"

You can adjust your ignition timing. But must use a method that doesn't change your cam timing.

***this is assuming that the rule will be clarified, and that cam timing is not free***



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Daryl DeArman

[Knestis]

Marty's point above is well made but the suspension is an area where adjustments can be made with the stock parts.

Geo's on the mark, I think, with the reminder that the rules are about parts. My (tongue-in-cheek) plan to use an offset cam key on the Golf is illegal, NOT because the cam timing must remain stock but because I can't use a Mercedes offset key rather than the stock part. (That was the trick that the SSC guys used to use in the MkII's.)

On the other hand, if I could adjust the timing without using an illegal part - or modifying a stock one, say be milling the keyway in the cam - then I could change it...?

Surprisingly, I almost buy this.

K

[Quickshoe]

Originally posted by eh_tony!!!:
I'm in for a 6 pack that the CB's response will be the standard "rules are adequate as written" with no additional clarification of leglity/illegality.

That would be a real bummer.

I stated many posts ago that I thought that their intent was to "allow an offset key *if needed* to return cam timing to FSM specs after milling the head. Thus the choice of the word may instead of must.

This rule may be clarified and cam timing will now be clearlyopen. Maybe that wasn't the initial intent but given the technology available on some of the cars now, they'll open it up and the rotaries will get screwed again.

Unless, of course, the rotary folks will be allowed to relocate their ports. As long as the duration and size of the openning remain unchanged, why shouldn't they be allowed to?

-Daryl DeArman

[eh_tony!!!]

Originally posted by Quickshoe:
"...no permitted component/modification shall additionally perform a prohibited function"

You can adjust your ignition timing. But must use a method that doesn't change your cam timing.

***this is assuming that the rule will be clarified, and that cam timing is not free***

Unless you shave your head and have adjustable cam gears...lol