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distributor change


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anyone ever tried the hot spark distributor in the lb20? looking for feedback in case i need one in the future. I HAVE BEGAN TO INVEST A LOT OF TIME AND MONEY INTO MY TRUCK.JUST WANT TO MAKE SURE I WILL HAVE PARTS TO MAINTAIN IN THE FUTURE.

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  • 3 weeks later...

I took apart a matchbox dizzy today. I noticed one slot on the cam is longer than the other.11.5 is stamped on the top of the cam.one slot checks 10.6 and the other checks 9.4.Why are the slots uneven? i want to understand this whole distributor deal. Would a factory datsun 620 shop manual explain this to me?

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I would imagine that the distributorguy would know the answer, he builds performance distributors and explained to me how to re-curve my matchbox so the engine would quit knocking.

He has not been here since the middle of July, if no one else answers the question them PM him.

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dizert.bmp.jpg

 

What slot are we talking about???

 

 

The '69 620 and the '80 720 used the matchbox. A Nissan FSM (factory service manual) for those years will explain how it works, yes.

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Ahhh. those slots. I wouldn't worry about them as long as the total timing at 3k is 32-340 with initial timing at 120 . The weights, springs and slot lengths determine how much total mechanical advance and how fast it comes in. I wouldn't obsess over it.

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Like I said, the  distributorguy likely knows why one is shorter than the other, if I were to guess I would say the shorter slot bottoms out first therefore making it harder for the second slot to bottom out which would slow down the advance at higher rpms, it might be a built in buffer, but that is just a guess.

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is there any such thing as rebuilding a vacuum advance?i got one off of an old points distributor i picked up from the local salvage yard friday.i found a old points distributor in the truck bed of a 620.the tag on the fire wall said it was a lb20.the numbers on the distributor was D4A4-07.it was rusty so i put it in a can of evapo-rust to clean it.The shaft is stuck.so after i got the rust off. i sprayed the whole thing in PB blaster to hopefully free up the shaft.

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D4A4-07 appears to be a '77 distributor.

 

Mechanical advance starts @ 600 maxes out 110 @ 1950 (distributor degrees)*

Vacuum advance begins @ 6.7 inches of mercury maxes at 6.50 @ 11.8 in. hg. (distributor degrees)*

 

* for crankshaft degrees, X2

 

D4A4-97 isn't that helpful. Look on the body of the distributor for the part number, I can then tell you what it's from. Begins 22100-????? need the last 5 digits.

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22000-B8001 is used on the '75 California 620 and '75 through '77 federal and Canada trucks.

 

Naturally any points or EI distributor will fit and work in any 4 cylinder L series, but the 22000-B8001 is specifically curved for these years and applications... strictly an emissions thing.

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i want ever use it.just picked it up because it was there.but on the other hand i guess i could just keep it in case.is there any advantage in running an all brass distributor cap.

Edited by nissan720
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On 8/16/2020 at 6:37 PM, datzenmike said:

D4A4-07 appears to be a '77 distributor.

 

Mechanical advance starts @ 600 maxes out 110 @ 1950 (distributor degrees)*

Vacuum advance begins @ 6.7 inches of mercury maxes at 6.50 @ 11.8 in. hg. (distributor degrees)*

 

* for crankshaft degrees, X2

 

D4A4-97 isn't that helpful. Look on the body of the distributor for the part number, I can then tell you what it's from. Begins 22100-????? need the last 5 digits.

 

If static timing is 100 and the mechanical maxes out at 110 then 310 total. I think 10 isn't enough. All L20B are 120 plus the 110 mechanical for 330.... much better

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well got fortunate today and found a dizzy out of a 1982 datsun 210 with 170,000 miles on it. Guyalso had some 1982 maxima dizzies as well so i picked up one of those for parts.he told me he had 3more maximas on the yard,but it was a little late when i got ther.its 2.15 hours one way from my house.i told him i would be back next Saturday morning. he has about 3500 cars .

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