Provided the weather is nice, I will be running my car at the track this Friday for my b-day.

The other day I adjusted my cams gears because the setting on the exhaust cam seemed to skew from the original setting.

The car seemed to be VERY torquey before I adjusted it, but lacked/lost some power on the top-end after about 4-4500rpm.

My questions are:

What settings have any of you had success with? Care to share?

At about what point in the cam gear setting range would a piston meet a valve?
(Obviously DONT WANT THAT TO HAPPEN)

BTW: I have 8.6:1 pistons and Crane # 14 turbo-grind cams.

Thanks

The only thing you can really try with them cams unless you put it on a dyno, is put the exhaust to -2 degrees. I had them cams and reall didnt get anything outta them.

You are turbo, right?

With the dish pistons and small exhaust cam, you could go a long way with it. I had the 14's and retarded mine as much as -6*. If you retard only the exhaust cam, you're gonna increase your overlap, which isn't what you want when boosted.

Play with it, you're going to the track. Run 2/3 runs each at 0/0 (exh/int), then at -2/0, -2/-2, -4/-2, etc. After you adjust them, turn the motor over with a wrench to see if it spins freely. You should fine, but check it just in case. To make it easier to turn, you could pull your plugs as well.

be careful adjusting your exhaust cam too much as thats where the cam sensor magnet resides... There was discussion about it throwing a wrench into all sorts of things with timing etc.

Originally posted by djtrickee
be careful adjusting your exhaust cam too much as thats where the cam sensor magnet resides... There was discussion about it throwing a wrench into all sorts of things with timing etc.

IIRC, it has some bearing on spark and injector timing. I may be wrong, but I ran mine that way and it seemed to run better.

Thanks for the help so far. I adjusted the exhaust cam back to what is/close to 0/0 (exh/int) and seemed to have lost power and torque.

As far as turning the engine over manually, thats what I did thinking that if it stopped, then something wasnt right. Glad to hear I did that properly. THANKS.

So if I dont want overlap, then I should change the intake setting as much as the exhaust setting? Am I understanding you correctly?

Thanks

The camshaft angle sensor doesn't have nearly the resolution that the crank angle sensor has, i.e. it isn't as important in the timing calculation as the crank angle sensor is. I'm willing to bet you can play with it a lot before it will throw a check engine light for crank/cam out of time. I ran something like -3 on the intake and +3 on the exhaust at one point, and I never got a CEL or noticed anything else strange.

After you change the angle of the exhaust cam check the spark advance with an OBD2 datalogger vs. no adjustments. I'm interested to see if 2-3 degrees of error would actually do anything in regards to ignition. With regards to fuel, having the injector fire in error by a few degrees will probably do nothing.

Huh, I learned something today, lol.

Originally posted by ner947
The camshaft angle sensor doesn't have nearly the resolution that the crank angle sensor has, i.e. it isn't as important in the timing calculation as the crank angle sensor is. I'm willing to bet you can play with it a lot before it will throw a check engine light for crank/cam out of time. I ran something like -3 on the intake and +3 on the exhaust at one point, and I never got a CEL or noticed anything else strange. After you change the angle of the exhaust cam check the spark advance with an OBD2 datalogger vs. no adjustments. I'm interested to see if 2-3 degrees of error would actually do anything in regards to ignition. With regards to fuel, having the injector fire in error by a few degrees will probably do nothing.

3 degrees plus or minus is the window the ECU gives the cam signal to be out of phase with the crank signal. It has more resolution than you think, because it's used in reference with the crank sensor. The signal in itself has large gaps, but those gaps together with the crank signal are accurate.

If you throw it too far out of wack with your cam gear tuning you could be spraying fuel on a closed valve. The cam signal doesn't effect spark advance but injector timing.

Exile Racing Technologies
http://www.exileracing.com
Go that way, really fast, if something gets in your way... turn.

Originally posted by 95greenhrcgs
So if I dont want overlap, then I should change the intake setting as much as the exhaust setting? Am I understanding you correctly? Thanks

Yes, that's correct.

If you retard only the exhaust cam, it's closing later. The intake cam opens as the exhaust cam is closing. If you retard the exhaust X*, then that's X more degrees of overlap. If you retard them both, the same amount, there's no added overlap. If you advance the intake cam, it opens ealier and adds overlap.

* = degree

retarding exhaust cam X* = X* increase in overlap
advancing exhaust cam X* = X* decrease in overlap (<---- don't do it)

retarding intake cam X* = X* decrease in overlap
advancing intake cam X* = X* increase in overlap

retard exhaust X* + retard intake X* = no increase in overlap
retard exhaust X* + advance intake Y* = X*+Y* increase in overlap

Thanks guys, you are the best!!! I will see what goes down at the track this Fri and share regardless of the outcome of my driving and/or the car.

Thanks again
Jon

ummm, when you create more overlap, you are pulling more mixture mass into the cylinder, but are inevitably blowing some fresh charge straight into the exhaust, right? So wouldn't the O2 sensor pick this up and tell the ECU the car is running rich, subsequently leaning out the mixture and negating any gains you got by creating the overlap in the first place? I was intrigued by the concept of the cam gear adjustment, and when I started thinking about why the engineers wouldn't do it in the first place, this is what I came up with (along with maybe poor gas mileage)
-Or is this a track only trick, where you adjust the cam gear for one run and the ECU doesn't have enough time to adjust the mixture.
-Or can you pull this off all the time if you have a standalone engine management system?
Please cure my ignorance.

Originally posted by silverarrow
Please cure my ignorance.

LOL, sorry, I had to.

Anyway, I'm not really sure. That may be why cams affect smog testing.