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HybridZ

240Z Timing Advance


Miles

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Just doesn't sound like it would work. The reason this came up is that my engine lacks throttle response since I installed new Ztherapy SUs. After tuning the carbs I dailed in max advance, but the timing light shows that I am dead on TDC at idle. Throttle response is a little better, but not like with my old carbs.

 

Thanks

 

Miles

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You should be at ~12* BTDC at idle, depending on your setup. (standard disclaimer here) Likely you've retarded timing all the way! The car wouldn' thave much punch at all at 0* timing at idle...

 

Er actually, is there any chance you have the distributor gear out a tooth? You should be able to adjust in the 8-14* BTDC range if it is in the right spot no problem.

 

The car will run if the distributor is 180* out. (most rotors cannot be installed backwards, the whole distributor, wires, cap etc would have to be) It will run like total crap if it does run, backfire through the intake, etc.

 

If anyone has messed with the distributor, I'd take a look and make sure firing order is ok, timing is good, and go from there.

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Drax

 

I advanced the distributor as far as the set screw would allow and under a timing light the timing mark is right at TDC. With the no. 1 cylinder at TDC center the rotor is pointing a few degrees past the no. 1 connector on the distributor cap. I tried moving the rotor by loosening the distributer, lifting it, and repositioning the rotor to line up with the number one connector in the cap. When I drop the distributor back in it either wont go in due to the rotor position or it will only drop into place if the rotor is back to its' original position. It seems that when the distributor is lifted and the rotor turned it will only go back in one way. I am assuming that the drive is slotted in a way that only allows it to be installed one way. Using a timing light I can turn the distributor clockwise and retard the spark alot, but can't get much advance going the other way.

 

Thanks

Miles

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Your lower shaft/gear is probably off on the crank gear setting but don't drop the oil pump to set it right, just move your plug wires around one cylinder distance and that may be what you need to put you in the proper timing adjustment range. If you're running points, make sure the dwell is set properly before setting the timing. When you set your valve lash, be sure to check the camshaft timing (advanced, retarded, etc.) as this can have a large effect on performance. DAW

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What DAW said, but I'd drop the oil pump and get the gear in the right spot to avoid confusion at a later date... It's a bit of a bitch, takes a couple of tries to get right usually, but it is worth doing it right.

 

DAW's method will verify if you are out a tooth though.

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I have to wonder if this might not be a result of the vacuum advance messing up your timing settings. If it still works, and you held the rpms at 3500 or something and then set the max advance, the vacuum advance would kick the timing up significantly. If you didn't set timing with the vacuum disconnected, try again.

 

It just seems odd that changing the carbs would have such an effect. Was anything else done at the same time?

 

One more thing. I don't mean to insult your intelligence, but there are 2 lockdown bolts on the later dizzys, and IIRC there are 2 on the 240 dizzy as well. One is pretty obvious and uses a 10mm bolt, the other is hard to see but uses an 8mm bolt and is on the opposite (hard to reach) side of the dizzy and is tucked up underneath the dizzy body. I've known people who owned their Z for years and had never found the 2nd hold down. If you haven't already tried to adjust it there, give it a shot. IIRC you can get more adjustment out of the 8mm adjuster than you can out of the 10mm one.

 

Jon

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