280z fuel consumption problem...

[grantf]

Factory Timing is I think the 10 deg mark. I would start there and see if performance is improved or not. I set mine to 10 deg but latter moved it up to about 12. May be a stupid question but do you have it set 7 deg retarded instead of advanced? Anyhow another thing to test is the vacuum advance on you're dizzy to verify that it is working properly.

[Z train]

how would you know what the best timing is?

Bump it in 2 degree increments.Sooner or later it's not going to like the increase.Then drop it down 2 degrees.Tuning is all trial & error.THere is no magical number that ANYONE can tell you will work best.

[cozye]

I was told I needed to be at 7deg for california.

I'm curious, where does this information come from that it needs to be at 10-13 ? And what would the benefits be

Also, I've been reading a bit more, and I see people are able to go to 20deg and such.

My timing won't let me go past ~12deg, but I can go the opposite direction way off the timing marker.

Could anyone explain why this happens?

Also, my engine ticks now at idle, but ever since I timed it to what I believed was 7deg(which I don't believe it truly is anymore) my engine has ran better than ever.

One last thing, I had about 2 instances where I heard a weird metal grind from the engine bay when I revved up the engine around 4krpm that last maybe 1 second. Any ideas as to what this could be?

10 degrees comes from the factory service manual, page ET-7. Its also a sticker on the hood if it hasn't been taken off. There is no separate value for ca cars.

Running it low is just masking other problems, you will get lower vacuum, less power, poor fuel consumption.

Historically, tuners have advanced timing as far as they can without causing detonation or spark knock. Typically some advance will give you slightly more power.

That being said, your timing marks could be wrong. Check TDC of the motor and verify that the pulley mark lines up with 0. Sometimes the pully slips, which would make the mark wrong.

Next thing I would do would be to take the valve cover off, do a hot valve adjustment, and while you are in there check the valve timing by getting motor at TDC at inspecting the cam pulley mark. Instructions are in th fsm

No idea what your grinding noise was, but it shouldn't do that obviously

Edited December 31, 2011 by cozye

[cozye]

Oh, and the reason why you are running out of adjustment it of the distributor is you either have excessive shaft play, the plates on the inside need adjusting, or the old ignition components are worn. Mine was like that until I put in an optical ignition trigger and phased it properly, now it's dead on with plenty of range.

[Milenko2121]

Thanks for the tips I'm sure my pulley is off then, but I like how my engine is running with this timing. It's smooth and clean, also my gas mileage has gotten much better. No true numbers yet, but I'm guessing I'm getting 18mpg maybe even 22. I'll find out in a week or so when I fill up.

Also, found out that metal on metal noise was the skidplate on my catback. it's loose and rattles.

And I apparently need a new exhaust. My cat has a hole that was welded, the exhaust pipe has multiple holes and is rusted as well as the muffler.

I think that could explain my engine not running as well, and the shakiness.

Edited December 31, 2011 by Milenko2121

[Zed Head]

7 degrees is probably from the 1976 specs (my car and FSM). It's more likely that your pulley is fine and your timing is really at 7 degrees.

Your distributor might be a little off. There are many common ways to install them incorrectly but also many ways to make it work, with no damage. 12 degrees will probably be just fine until you start tuning for performance. As you've found, 7 degrees runs well, as it should. You're just not getting the absolute most performance out of your engine.

You could bump it to the 1977 spec. of 10 right away or even 12 if you're running premium, with no problems likely. It would probably be a little peppier and maybe get a little better mileage.

[Z train]

Find TDC and see if the line is at 0 or just a hair before.Really long odds on the balancer being the problem.

[zpizzaman20]

You should be over 25 mpg on the highway at 65mph

[Milenko2121]

Find TDC and see if the line is at 0 or just a hair before.Really long odds on the balancer being the problem.

whats the best way to find TDC? ive been reading about it, but im still a bit confused on when to know how to do it perfectly

[cozye]

Use a wooden dowell rod in the spark plug hole, TDC is when that #1 piston is at its very top position. Get it close then mark the wooden dowel, then go a bit back and forth on the crank until its at the highest position. I usually take the fan off and use a wrench on the crank pulley nut to turn the motor

[Milenko2121]

Use a wooden dowell rod in the spark plug hole, TDC is when that #1 piston is at its very top position. Get it close then mark the wooden dowel, then go a bit back and forth on the crank until its at the highest position. I usually take the fan off and use a wrench on the crank pulley nut to turn the motor

the #1 piston is the one closest to the firewall right? Just double checking >_<

I'm still learning here, I've only owned this Z for a little over a month, and it's the first car I've ever worked on, and I've done a lot so far mostly thanks to this site.

[buysell]

the #1 piston is the one closest to the firewall right? Just double checking >_<

I'm still learning here, I've only owned this Z for a little over a month, and it's the first car I've ever worked on, and I've done a lot so far mostly thanks to this site.

#1 piston is closest to the radiator.