Ignition timing for 240z with L28, MSD, triple weber, 78 ingiton and distributor

[jaynez31]

Hi, I am again, I have to live with Classic Z car, huh.

Anyway, I am dificult finding corrent timing setting for my 240z

has various mods:

1. the engine is L28 from 280zx with P-79 which proted and performance cam.

2. MSD ingition box with blaster coil with 8mm taylor wires.

3. '77 ignition and distributor(from privious owner's recipt) and

4. Motor sport header and 45 triple weber with cannon.

The L28's timing is 8B-10B. How do such mods affect timing? It may be bit advance or retard?

It might help my over heating issue too.

____________________________________

240z rocks

[Victor Laury]

Try setting your timing for full advance instead of initial. Since different dizzys have different mechanical advance settings, It's hard to give someone a initial setting that will work in their situation. unhook the vacuum advance and use the fast idle screw to raise the RPM to 3,000. Set the timing to just under 35 BTDC ( a "turnback" dial timing light makes this easy). Now take it for a ride, and try to load up the engine by accelerating in a too low gear (4th at 25 MPH for example) it should ping but not much. If you can't make it ping in that condition, You can afford more advance. If it pings like mad, you need to retard it a touch. This test will simulate high speed driving in a way. When your really in the throttle at 120+, with the wind load, it's just like the low speed test above, except, you don't hear the pinging with all the engine/wind noise untill you melt a piston.

Once you've got it dialed in, I'm sure you'll find your total advance in the 32 ~ 35 range. Now, record your intial advance and you'll be able to discrerne your dizzy's advance spec.

your total is 34

and your intial is 19

so that's 15 degrees of mechanical advance

Your dizzy has a 7.5 advance plate (Lucky, you have the "Euro" dizzy)

your total is 34

and your intial is 15

so that's 19 degrees of mechanical advance

Your dizzy has a 9.5 advance plate

your total is 34

and your intial is 12

so that's 22 degrees of mechanical advance

Your dizzy has a 11 advance plate

Let's say your total is 34

and your intial is 6

so that's 28 degrees of mechanical advance

Your dizzy has a 14 advance plate (now I suggest you adjust your timing by replacing that god-awfull smog dizzy)

[Victor Laury]

Edit - set the idle at 3,000 RPM to check total advance

[jaynez31]

Oh, well, thank you for the advice. I still have a couple questions.

Since my z has 78 ignition and distributor with triple weber, I do not see vacume advance line from weber to distributor vacume advance port/inlet. Should I find a vacume outlet/port from triple weber cab? Shall I leave it alone or plug it.

I checked timing yesteraday, I noticed that privious timing setting was way retearded/too advanced. I did not remember, but I shold say the distributor adjusting bolt was far end of the engine side of the adjusting worm shaped groove/hole. I shold say 30-40 ATDC or BTDC?

I am not cofortable enough playing around the idle adjusting screws to do above procedure discribed by victor. I probably get help from a shop people or special shops. Or after I purshase the books of Weber Cab and Datsun manual to know more basics. Until the day, Hopely I can drive my car which this eveing I set ingition timing by 14 degree on the timing light with white mark on the crankshaft pully which aligned with the triangle shaped sign from the engine block. Compare with privious timing setting(the distributor adjusting bolt was far end of the engine side of the adjusting worm shaped goove/hole side of the distributor) whcih compared with 14 degree BTDC setting was the distributor adjusting bolt was settled middle of the the adjusting worm shaped goove/hole side of to the distributor cap.

This setting is better idling and running than before. Notably the water temp dropped about 10-20 degree, but it is still high between 200-230 degree range.

I am going to get new/used radiator this weekend, then I might be able to do the full timing set up which victor explained me.

thank you

jaynez31

Just like my 240z, I am from Japan too, what's heck.

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