Newb lookin to solve timing issue.

[ninjaboot]

Ive got an 83 720 with as stock as you can get 2.2. I was just wondering if any of you Datsun Guru's might have the final word on just the right degree of timing BTDC. Is this a nebulous every engine needs its own final tweek thing or is there an atomic clock precise degree to witch all who respect the big D must adhere to?

[RoadRace]

volumes have been written on ignition timing and the factors that control its effectivity in specific applications. Your question is too general to get a usable response.

 

short answer: there is a sticker under the hood somewhere, read that.

 

oh, by the way - welcome to Ratsun.

[murderwagon]

i always heard 10 to 12 degrees btdc and makes sure the vacuum advance is unplugged and the vacuum line plugged if you got one

[DanielC]

Advance it till it knocks on hard acceleration, and back off 2 -4 degrees.

If you have loud exhaust, be careful. Knocking can destroy an engine.

[Spades]

keep in mind folks, if this is a 2.2 in a 83, its a naps motor. this isnt a L series, so the stuff you are talking about isnt quite right. naps dont take as much timing, they dont rev as high, use differant head design and distributors, and alot of them have the 8 plug distributor and WAY less timing advance.

 

this is a Z22 right? i have the specs for it at work, if no one responds by the time i grab the specs, i can get the factory settings for you.

 

if its a 8 plug distributor, because of the dual plugs, you will want to run WAY less timing than the L motors...10-12 is fine for a L motor, and my 4 plug z20s after mods can handle 12 degrees, but for a 8 plug motor the specs are more like 3 to 5 degrees.

 

the factory spec for my z20s is 8 degrees, and i think for the 8 plug Z motors it was like 4 degrees base timing.

 

if you set your timing to 10 degrees on a naps, expect when at low idle to get some weird popping out the exhaust every so often, and the engine to try to stay running even after shut off, and other symptoms of timing too far in advance.

Edited November 7, 2009 by Spades

[ninjaboot]

Thank you spades. You wouldn,t believe how many different answers I got from local mechanics. Ive been running it 1 degree retarded which has been close to where I want to be. I do have some engine run on intermittently but I have a sneaky suspicion somethings hanging up in the choke as it usually settles after I tap the accelerator. Thanks for the responses.

[ninjaboot]

P.S. yes it is the Z22 with the 8 plug setup. Yay.

[datzenmike]

The timing for an '83 manual or automatic is 3 BTDC. But like you said all conditions including altitude or the brand of fuel you use can cause it to require slightly more or less.

 

The reason why the NAPS dual plug motors need less advance is... the dual plugs. Lighting the fire in two locations shortens the burn time. To get the most use of the violently expanding gasses in your combustion chamber, you want it pushing down on the piston at a 'sweet spot' about 17 degrees ATDC. Because the engine is spinning so fast and it takes a short time between ignition and maximum pressure it's best to 'light the fire' slightly early to arrive at the 17 degrees on time.

 

For the single plug L series the burn time needs about a 12 degree ignition advance to get there on time. For the dual plug NAPS with two ignition points the time needed is shorter and so the advance is also shorter.

[rudolfgreen]

Nice thread. ;)