Cam Timing

[Geo]

Originally posted by Banzai240:
So, I'll conceed that all other cases must meet an acceptable range for factory cam timing specs. BUT, the allowance of adjustable cam gears is an allowance for them to be adjusted within the limits they were designed to be adjusted within, or so me thinkist...

No. If you shave the head and it alters the cam timing there is absolutely nothing requiring the cam timing to be reset to stock.

If you believe that allowable specs are dicated by parts, factory cam gears that are used in such a fashion to create more advantageous (or not actually) results would be entirely legal. I would suggest this is absolutely OK. I will continue to believe this until someone shows me where the ITCS governs specs and adjustments in any way other than governing the parts.


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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

[Banzai240]

Originally posted by Banzai240:

BUT, the allowance of adjustable cam gears is an allowance for them to be adjusted within the limits they were designed to be adjusted within, or so me thinkist...

You know... I've thought this over a little more, and I'm going back to my original position... The mere allowance of a stock adjustable timing gear... the fact that it's seperately addressed in the first place, means that it can be "used"... Why would you allow an adjustable piece but not be allowed to adjust it???

There is some validity to the arguement that the specs must fall into those defined by the manufacturer, per our "blueprinting" rules, but even this could be argued to be overruled by the specific allowance for the adjustable piece in the first place...

I'll tell you what... if it's important you you all... I'll write the darn letter myself...

Or, I suppose I could just bring it up on Monday nights ITAC con-call...



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Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX

[Banzai240]

Originally posted by Geo:
Where the ITCS specifically states you may use stock adjustable cam gears and doesn't place any limits on those adjustments, I believe you can use the full measure of the adjustment allowed by the part (see above).

Yah... that's what I was trying to say!



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Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX

[Ron Earp]

(In the Jensen's case, the factory probably put the adjustable gears in because they: couldn't make accurate parts?..or they hadn't figured out what the specs should be?...or they figured it was the easy way to have the car meet the emission requirements in different markets. I doubt that they included it with a note in the owners manual or the FSM..."Have fun guys, the engine really rips at 10 degrees after"!)

Interestingly, in the manual there are six specifications given. The gears have 3 marks apiece and they listing timing data and ingition timing data for six combintions, although there are more combinations than this. Now, not all Jensens had this adjustability, late 73s and 74s seem to, 75s seem not too.

Still, I like the other question better - what happens if I need new cams? JH no longer exists. Lotus does. Lotus built the motor and if I call Lotus and order cams for my JH I will not get the same cams that I got back in 1974 because the manufacturer has superceeded these cams with a modern design. Is this legal? I understand in VW land Rabbits do this with some sort of G-grind cam in a similar situation. I don't need cams right now, but I will for my spare motor. My first motor is getting run as is, I'll be the limiting factor anyhow, now motor power production!!! ;-)

As for timing, well, I'm going to run the car and run the timing IN THE MANUAL that feels best.

And, from doing a lot of work on the JH I feel JH put them there to meet emission requirements. This was in the dark ages of emissions and I think the reason they specify different timings is so the things would pass emission but allow the owner to revert them to actually make a little power. For example here are three from the manual:

36 BTDC
56 ABDC
66 BBDC
21 ATDC

26 BTDC
66 ABDC
66 BBDC
26 ATDC

21 BTDC
71 ABDC
71 BBDC
21 ATDC

You'll notice this is all with the same two cams of course, just different factory spec timing. And, there are different cams depending on engine serial number, and different gears too, to make matters more complicated.

It is commonly accepted the cars never made the 140hp they were supposed to, but only around 125hp or so. Therefore, I don't think I'll be passing any of you fellows so don't worry.


Ron

[Geo]

Originally posted by rlearp:
Still, I like the other question better - what happens if I need new cams? JH no longer exists. Lotus does. Lotus built the motor and if I call Lotus and order cams for my JH I will not get the same cams that I got back in 1974 because the manufacturer has superceeded these cams with a modern design. Is this legal? I understand in VW land Rabbits do this with some sort of G-grind cam in a similar situation.

Since you asked, IMHO the cams for the JH are simply NLA.

Also, the legality of the G-grind cam is still in question IMHO.


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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

[Ron Earp]

Sorry, new here. NLA? Not Legal At All? Not Legal Anywhere? Not in Los Alamos?

R

[Banzai240]

Originally posted by rlearp:
Sorry, new here. NLA? Not Legal At All? Not Legal Anywhere? Not in Los Alamos?

R

No Longer Available...

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Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX

[Bill Miller]

Ron,

NLA = No Longer Available.

George,

You really are funny. Once again, ITCS says that you have to use stock timing if you swap phenolic/plastic gears for metal ones. Yep, special case, but it does state that you have to use stock timing.

Interesting position that you have on using stock parts. What happens if you buy stock valves for your car and they happen to be slightly larger/smaller than the specified valve size? And when I say 'slightly', I mean .001-.002 of an inch. Keep in mind that when there are no specific tolerences mentioned, specified dimensions are absolute.

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

[Bill Miller]

Originally posted by Banzai240:
It's been stated numerous times and should be rather obvious... HP potential is considered stongly in the process...

No Darin, what's been stated is that you guys are using a 'Miller ratio' for each class, and an appoximate 'hp gain' for an IT prep. I don't think you or any one else on the ITAC, have come out and said that you look at each marque/engine on a case-by-case basis. But it's no surprise that you just try and blow over the issue rather than addressing the question at hand.


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

[Ron Earp]

So if it is no longer available what do I do? Use what Lotus sends me?

[Geo]

Originally posted by rlearp:
So if it is no longer available what do I do? Use what Lotus sends me?

You scrounge for NOS (new old stock) which would be unlikely, or you look for serviceable used cams. Or I suppose you decide to be a cheater.


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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

[Geo]

Originally posted by Bill Miller:
George,

You really are funny.

Yeah, but looks aren't everything.

Originally posted by Bill Miller:
Once again, ITCS says that you have to use stock timing if you swap phenolic/plastic gears for metal ones. Yep, special case, but it does state that you have to use stock timing.

I agree. If you swap phenolic/plastic gears for metal ones they must use stock timing. Never debated that.

Originally posted by Bill Miller:
Interesting position that you have on using stock parts. What happens if you buy stock valves for your car and they happen to be slightly larger/smaller than the specified valve size? And when I say 'slightly', I mean .001-.002 of an inch. Keep in mind that when there are no specific tolerences mentioned, specified dimensions are absolute.

Well, if there is no tolerance spec'd in the FSM I'd say you are illegal since valve sizes are specifically called out in the ITCS. Of course, if I were building an engine I'd check to make sure the valves weren't illegal before I installed them in the engine (well, head to be specific).


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

[JeffYoung]

George, you are knowledgeable and I enjoy your posts, but sometimes, your attitude pisses me off. Ron is new to this and just seeking some advice -- the "decide to be a cheater comment" was not called for. I've watched him build this car and he is dedicated to making it legal.

Ron, check the GCR but I think you can ask the SCCA to, in the case of NLA parts, run the cams Lotus would supply you. It has (if I remember correctly) happened before with the VWs and the Datsun 510s.

Jeff

[Geo]

Originally posted by JeffYoung:
George, you are knowledgeable and I enjoy your posts, but sometimes, your attitude pisses me off. Ron is new to this and just seeking some advice -- the "decide to be a cheater comment" was not called for. I've watched him build this car and he is dedicated to making it legal.

Jeff, relax. He asked what the options were and I told him. Some people would indeed decide to cheat. It's amazing what attitudes are out there. I said it the way I did to be direct. Cheating is cheating. I never ever ever said Ron was a cheater. Go back and read it.

Could I have chosen different words? Sure. I could have sugar coated the option of running an illegal cam. Wouldn't that still be cheating?

I meant no, none, nada, zero disrespect to Ron. Never have. Ron, if you were offended, please accept my apology because if you are, it was purely a misunderstanding.


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

[Tom Donnelly]

I don't understand the argument here. If a cam comes stock with adjustable gears, why is it illegal to adjust it? If a car comes with adjustable timing (ie the distributor) then you adjust it. How many cars are running with the FSM recommended advance?

And is a regrind cam illegal? You can take a stock cam and have it reground to factory specs? Or at least I thought you could. Same lift, same duration, same overlap. Just reground to get rid of bad spots. Or am I missing something here. Lots of rebuilt engines have a regrind.

My motor was done by an engine builder, so I bypassed all these questions and bought a professional and legal engine.

Tom

[JeffYoung]

George, my bad and my apologies. I overreacted.

Jeff

[Ron Earp]

George,

What is NLA? No longer available. When it is no longer available do you use what the manufacturer suggests? That is the question, no more, no less. And no, I will not become a cheater if you're wondering. I would think from the short time on this board and the questions I air in public people would have figured that out by now. Cheaters don't ask "can I????", but people trying to learn and follow the rule do.

I have four sets of cams now - only one pair is worth a darn and it has a crack on one exhaust lobe, but I think runnable. I believe I can chip the piece off, file it down, and run it since it doesn't contact the valve cap. The other pairs are beyong help, but, I tried to get what I could and bought them off Ebay. Blanks are no longer available according to Delta and Dave Bean, therefore, what is one to do? I'll find some sooner or later, but the question still remains.

I am not complaining. I choose to build this car. I'm sure some responses might be "build a Honda, RX7, etc." but one chooses what one has an affinity for, and this is it. Hell, the tougher road is always more fun anyway, you learn more and have a better time.

Besides, if nothing else I entertain you guys and give you something to post about! ;-)

Ron

[This message has been edited by rlearp (edited September 23, 2004).]

[Banzai240]

Originally posted by Bill Miller:
I don't think you or any one else on the ITAC, have come out and said that you look at each marque/engine on a case-by-case basis. But it's no surprise that you just try and blow over the issue rather than addressing the question at hand.

Bill... It's also no suprise that you'd take my answer and turn it against me for your own gain...

I said that HP potential is taken into consideration in the process... What does that mean to you?

To me, it means that you look at the package under consideration and try to estimate what kind of output it's going to produce...

Do I really need to detail EVERY component that is considered when answering your question? Besides... can YOU tell me just how much power can be gained by messing with the cam timing on a stock system with stock cams??? What do you think it's worth?

I'm willing to tell you this much... with our current methods and means... there is NO WAY we are going to try to be accountable down to the 4-5hp margins we are talking about with something like this. Without a lot of technology and test engines, we can't possibly be expected to get our numbers for potential that close... Besides, this is IT... the intent of the class hasn't changed...

------------------
Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX


[This message has been edited by Banzai240 (edited September 23, 2004).]

[Geo]

Originally posted by rlearp:
What is NLA? No longer available. When it is no longer available do you use what the manufacturer suggests?

Technically, it's not that simple. By the letter of the law, to use another part it would have to be listed as a supercession.

Originally posted by rlearp:
And no, I will not become a cheater if you're wondering.

Actually, I never doubted you for a second.

Originally posted by rlearp:
Blanks are no longer available according to Delta and Dave Bean, therefore, what is one to do? I'll find some sooner or later, but the question still remains.

Have you tried to get in touch with any shops in Great Britain or enthusiast groups there?

Technically using reproduction cams is currently illegal, but we are working on fixing that sort of thing.

Since the engine is a Lotus engine I would think somebody would have a resource.

[edit] To edit out unused quotes

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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

[This message has been edited by Geo (edited September 23, 2004).]

[Ron Earp]

Yep, I am in touch with the JH Preservation society here and an Lotus engine builder in the UK. Since I run www.gt40s.com, and most of the GT40s are in the UK, I've got a lot of sources in racing/street stuff/concours, etc. That is why I know I can turn a set up sooner or later. But, someone still needs too look at that ruling. There are Lotus only cams that are within 0.015" of lift of the stock JH cam and with the same duration which are available now, off the shelf. There is no way this will make a performance difference, given the head castings etc. that I cannot change.

It is just the JH cams were used no NO Lotus motors, that is in a proper Lotus, and since JH only built the cars for 2.5 years in low volume you can see the problems. Lots of Lotus cams fit the motor, but those are not correct.

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



[This message has been edited by rlearp (edited September 23, 2004).]