Thread: Cam timing.

I know that there are a LOT of threads about cam timing; I KNOW I've been through, pretty much, all of them.

Buuuuuuuuuuuuuuuuuuuuut...

When the figures are talked about +/- degrees, are they talking CRANK or CAM?
There IS a difference?
Before I go moving the cams 10degrees, when I REALLY only wanted 5, and the valves decide to kiss the pistons... I'm really wanting to avoid THAT; as you could well imagine.

ALSO when it's stated +/-'X' and +/-'Y' does that mean that 'X' = INtake, and 'Y' = EXhaust?
Again I REEEEEEEEEEEEEEEALLY want not to cause any mechanical issues.

While I'm asking, are there any 'common' things that occur? As in more advance means more lower and mid with less upper, and vice versa more retardation means less lower and mid with more upper power?

I'm sorry if this has been asked one-million times before; I'll put on my flame retardant undies and expect to be roasted.

When giving cam figures you always give the intake first then exhaust.

At the same time it should still be posted like this In +5, Ex -2 or +5,-2.

When you get these figues it is cam timing but cam timing is in relationship to the crank so they both go hand in hand.

Adavaning the intake and retarding the exhaust get the valves closer to hitting the pistons. It is all relative to the size of the cam and the pistons you have. This is a setup more for midrange power this will move the powerban lowerin the RPMs.

Retarding the intake cam keeps the intake valve open longer, which helps in top end performance, the cause effect of this is better volumetric efficency at higher RPMs

Adavncing Intake and Retarding the Exhaust cam will increas the over lap of a cam. This really works out on a car that has an exhaust tunned properly for the motor. This setup incrases the scavenging effect as to get the intake gases in and out of the exhaust.

say you wanted more power between 5000-8500rpm
sr20ve, with n1 cams
what sort of cam timing should i be looking at?

It is all relative to the header and exhaust on the car.

Lets say you have a header that is 4 into 1 32 inches long you could play around with the cams and see no power change anywhere.

Lets say you have a Charles Dunden 4 into 1 stepped Header 25 inches you could see a 5 HP change across the power band depending on what setup you are looking for.

Cams actualy only work good on a properly tuned header. ( Charles Dunden )

By the way that 5000-8500 RPM band is very broad to say this is where I want my power because a N1 cam really makes power from say 7000-8500 RPMs. So if you messed around with the cams lets say +5,-5 your power band might be 6500-8000. The spread of thhe power band will stay the same you are basically just moving it around to suit your needs.

Another question that I'd like answered is...

If you look at Genuine Nissan N1 cams, their designed to run on a head with 1mm shaved off it, from factory.
Are these cams designed and fabricated with the appropriate adjustments made to the cam timing to compensate for this; i.e. would these be +/-0 and +/-0 on a standard (not shaved) VE head? Or are these run at 'effectively' -10 and -10 (or whatever 1mm is) due to the head retarding them mechanically due to it's drop in height?

Or are the pulleys different to compensate?

If they are different all that you're doing by advancing them is making them closer to +/- 0 +/- 0 on a standard head?

Sorry if it's not reading too well. I'm unsure how to actually say what I mean without pictures, and hand gestures.

I was informed not to long ago by a friend that Nissan made 3 diffrent set of cam gears for the N1 motors. So I guess the correction factor was in the cam gear.

I am 100% sure Nissan left the cam alone instead of trying to fiddle with it.

Well remeber that unless we got to take a look at all the cams gears we dont know what Nissan was doing. I can say this which is my opinion, I feel that Nissan went fro more HP in the version 2s, so I guess we would be looking at a setup more like In-2, EX 0 or In -4, Ex 0. Remember these are just guesses.

INTERESTING!
I'll quiz the guys at Nissan to see what I can dig up, could be the solution to some peoples quandries?

Was after more a general guideline for maximising power up top, obviously some playing around will yield the answer, but be nice to have some theory behind what should work.

You can find the answer in the second post of the thread.

its always best to tune your cam gears on the dyno. There you will see what adjustments suit your set up.