Timing #3

[siteunseen]

A mechanic friend that I have lots of faith in suggested I install my new timing set at hole #3. Says it will give it a little more umph. His shop has a waiting room with an armoire and a flat screen. Rovers and MBs with engine covers. He started off on Datsuns and said they used to do that a lot that it advances the cam slightly. Any thoughts on this?

[Zed Head]

Pretty sure that I've seen similar referred to by one of those guys who seems to know a lot, on another forum. One of those old tricks.

It's interesting though that people will spend lots of time and money to get their cam set perfectly to the cam builder's specs., using a degree wheel and adjustable timing gear, but will throw an extra 8 degrees of cam advance in for more "oomph". Just an observation about engine tuning. Lots of mystery there, when it comes to cams.

If you search around Hybridz, you might find some threads. I think that Tony D had some stories about cam timing tricks.

If you're in the waiting room tight now and the question is what to watch on the big screen, the Euro 2012 semi-final is on in about 1.5 hours. If you're in to that.

[Wade Nelson]

I accidentally put a timing BELT on a Honda twin-cam engine one tooth advanced. From 3000 to redline the thing ran like a banshee. I never knew a CRV was a race car in disguise. Holy mother of God that thing was fast!

Alas, nothing is free. The owner complained about loss of low end torque. One of those boring people who shifts at 2k I s'pose.

So yes, if you want your Z to breathe better at the high end, advancing the timing CHAIN will probably give you that, but be prepared to pay for it with harder starting and some loss of low end torque.

NOW you understand why VVT --- variable valve timing --- is such a godsend on smaller, hi-revving motors.

[LeonV]

I accidentally put a timing BELT on a Honda twin-cam engine one tooth advanced. From 3000 to redline the thing ran like a banshee. I never knew a CRV was a race car in disguise. Holy mother of God that thing was fast!

Alas, nothing is free. The owner complained about loss of low end torque. One of those boring people who shifts at 2k I s'pose.

So yes, if you want your Z to breathe better at the high end, advancing the timing CHAIN will probably give you that, but be prepared to pay for it with harder starting and some loss of low end torque.

NOW you understand why VVT --- variable valve timing --- is such a godsend on smaller, hi-revving motors.

It's the other way around, actually.

Advancing the cam increases low end torque and takes away from the top end. This happens because the intake valve closure point is altered (obviously along with the others, but this one is deemed more important), and advancing the cam makes the intake valve close sooner. This improves breathing at low rpm by limiting reversion of the fresh mixture back into the intake, however the high end is sacrificed by the earlier intake close point as it doesn't take advantage of inertial ("ram") effects.

It's nothing to do with tricks or magic. Apply scientific method and you're there.

Someone should write a book titled "Suggestions from a Mechanic Friend" as a how-to guide, or rather, a "how-not-to guide".

[Wade Nelson]

Funny that you should point out I had it backwards. (Advancing vs retarding)

I actually believe I installed the belt correctly, partly because I had another mechanic inspect and confirm it before buttoning it up. (Cheap insurance!) The owner took it to a second shop (for other problems - CEL, Multiple misfire) and they CLAIMED the belt had been mis-installed. I never quite believed it, but ...gotta at least ACT humble.

So now I'm wondering if I had it right all along and the OTHER shop advanced it a tooth. (The CEL never went away even after the other shop SUPPOSEDLY corrected it, re-adjusted the valves, etc.)

And, a non-aggressive driver WOULD prefer low-end torque over hi-revving power...

I'm not sure that vehicle EVER got a correct diagnosis on the MMF, which was perhaps EGR related. (Recessed valves on two heads in a row, known Honda (B20) defect, but now I'm thinking the MMF was a CAUSE and not a SYMPTOM...)

But the whole affair DOES go to show you a single tooth / link of timing change can have a NOTICEABLE effect on performance, high-vs low end.

[Zed Head]

Apply scientific method and you're there.

Someone should write a book titled "Suggestions from a Mechanic Friend" as a how-to guide, or rather, a "how-not-to guide".

Kind of stating the obvious aren't you?

Experiments that yield measurable results are part of the method. So if someone (the mechanic in this case) has advanced the cam to #3 and felt more "oomph" then they've applied the method, and have knowledge. The discussion can revolve around what oomph means, but if your mechanic has done it and knows what happens, then you can only go off how well you trust him. If he was my mechanic, I'd ask him what he means by "oomph" and what I might lose by doing it - peak HP, for example, if what's described above is correct. If he's just working off internet rumors then you and your engine become the experiment.

[LeonV]

Kind of stating the obvious aren't you?

Usually, that's what it takes... it's not my HybridZ tagline fer nuthin'!

There is no mystery and no tricks when it comes to setting up a cam, if you know what you're doing. And to come full circle, looks like the OP should do some searching and educating himself. I've added a little background, and now it's time to search out the details.

http://www.datsport.com/racer-brown.html

[siteunseen]

I guess I'll expirement with it. If I do what he says then I've got him on the hook. Thank you all for your thoughts. Much appreciated.

Cliff

[madkaw]

Cliff,

I'd do it. I think I would install it on #1 hole first, drive it around and really take notice how it runs in every situation.

Then flop it to the third hole and drive it again. Once your timing chain is set, it's pretty fast to make an adjustment to 3 hole.

[LeonV]

Cliff,

I'd do it. I think I would install it on #1 hole first, drive it around and really take notice how it runs in every situation.

Then flop it to the third hole and drive it again. Once your timing chain is set, it's pretty fast to make an adjustment to 3 hole.

Hey, someone's using their head!

[olzed]

Cliff,

I'd do it. I think I would install it on #1 hole first, drive it around and really take notice how it runs in every situation.

Then flop it to the third hole and drive it again. Once your timing chain is set, it's pretty fast to make an adjustment to 3 hole.

It will be interesting what the results are.

[madkaw]

If you read Racer Browns article on cam timing he states that the rather long Datsun chain induces a retarding effect on cam timing- so why not counter act that by advancing the timing. I think a stock engine would benefit most by trying to gain low end grunt