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HybridZ

Phase difference<<Dizzy questions


Nismo280zEd

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Ok I've about had it with Z cars, or atleast triple webers. Determined to stop the backfire i spent the last 3hrs tuning. Only to find it backfires more. So I went through my 280 book trying to find the reluctor gap for the pickups said between .2mm and .4mm so i set it aroun .27 about half for both (have a dual pickup right now) Then i noticed a silver plate on the dizzy was WAY off to the right, figure that can't be right.. checked the book. It's the Phase adjuster plate, So I set that to where the book showed, then i started the car, umplugged the vacuum hose to the dizzy and set timing about 12btdc The car sounded healthier and more responsive, but at the same time... I lost my vacuum, it goes in and out. And it's not reading as high as it was before I started all this. So does the phase difference basically adjust the vacuum usage of the dizzy or? I don't know.. i'm confused. About ready to just put the pos efi motor back in and end all these nightmares.

 

-Ed

Triple Weber Hell

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Could be your vacuum pot is ripped/leaking on the dizzy.. May be only a small crack now, but at certian points it looses vacume. I don't even run the vac advance on mine. (75 280z w/zx dizzy) I just set more intital advance, and find it's very responsive. I had one of those silly dual pickup units in my car )stock) and could not get the thing to work properly. IMO there's too much other crap (thermotime switch, transistor 'box', ect) that it relies on to work the ignition properly, and its all 30 years old now.

 

I think maybe this is a carb problem.. asuming you've set the dizzy to factory specs and all is in good working order... but Im just thinking now.. I doubt the factory settings will perform well with triples..

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Everything I have read suggests ditching the vacuum. Not enough pulled from one runner with the triples. I just fired up my 2.9l motor with triple Del'Ortos on Monday. I tossed the stock distributor and went with the Mallory dual point. No vac advance and infinite adjustability to advance curve. If points prove troublesome, I'll pull one set and use the other to trigger an MSD.

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The 240 has vac as well. It is possible to not hook it up and to increase the length of the slot on the mechanical advance mechanism to allow more total advance without having to crank up the mechanical. Right now mine is 15 initial and 36 total advance.

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