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Newb ?'s for my '75 620...

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Whats up guys... ive got a 75 620 regular cab LWB truck. I was wonderin what i could do to upgrade the performance. Im COMPLETELY new to the datsun scene, so please bear with me, lol. I know absolutely nothing about the motor in the truck. What motor DO i have? What are the good, afordable performance mods to start with? Thanks a lot guys!

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You should have an L20B over head cam engine unless it was changed. To check, look on the passenger side of the engine at the back just below the #4 spark plug where the head and block meet. On the block there is a raised boss with a flat surface. You may have to wire brush the dirt off of it, but it will say L16 or L18, or L20B

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L16 and L18 are shorter stroke so higher reving the L20B has more torque to go with the larger size. Basically, bigger is better but you can get some impressive results from all of them. The L series was overbuilt, in that it has very strong internal components that seldom fail. I have 300,000 Km on mine, with one blown head gasket last spring $23 to fix. Oh yeah, they are easy to work on.

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I got the truck home yesterday. It runs like a top, but tops out at about 55, and it takes a while to get there... Could this be because of my vaccum line problem? If so, which ones are necessary to hook up? I plan on getting new plugs and wires, and changing the oil tomorrow. What other suggestions do you guys have? Thanks a lot. L8R.

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install pertronix electronic ignition, or the dizzy from a later model, and a msd blaster coil. if your o.k with wiring some stuff in, then go electric fan, that can save up to 15 real world hp!!! at the rear wheels too. if you have the original hitachi carb, then swap to dual side drafts, or the down draft weber, which is usually 320 bux on ebay. thats a good start for the motor, you can also sway in a 5 speed if your savy and do some reading here.

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Dizzy is the term for a distributor. An EI matchbox dizzy is an Electronic Ignition requiring NO points. It has a black box on the side the size of a 'matchbox' hence the name. It can be found on the later years of the first generation 200sx '78-'79 also the '79 620 truck and the '80 720 truck. The later model HL510 with L20Bs had them too. It's a nice upgrade and besides eliminating the troublesome points, gives a hotter spark and is good to 9-10,000 rpms. Drops right in and works but you need the matching coil from the same vehicle that the matchbox came out of.


If you get a matchbox you won't need a Pertronix. If you can't find a matchbox then a Pertronix unit can be installed in your old points distributor and will do the same thing.


SHADY280, Just my opinion here but if we could find up to 15 rwhp by switching to electric fans everyone would have done it long ago.


Hainz has an excellent vid for tune ups but a $20 Haynes manual will cover the more basic things you need to know.

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the electric fan conversion has been dyno proven by hot rod magazine, solid fans without a clutch on average save 25 hp, where as a clutch type saves 10-15 hp. they tested on several vehicles, and found simmilar results. most ppl never switch, cause you gotta mount and wire, and mounting can be tricky, and never ever use the thru the rad type "zap straps" they just bung up the core. why do ya think every import out there and most vehicles use electric fans now? and mike, you are absloutely correct about using the match box stlye dizzy, much easier, i had to grind my dizzies top to find the magnet on, except you can use any coil, it doesnt have to come outta the exact vehicle. i use a msd blater coil on my 280zx's and my 620, and have installed many more in other datsuns. you can even put a msd control box in with a bit of savy wiring, and the tach adapter in the z's.

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except you can use any coil??

Well what I understand, that is not true if you run the point coil without the ballast it will get hot and cook the insulation off the wires inside.Premature failure(burn up the points for sure). If running a Full 12volt thru it .

The MSD Blaster 2 is the same intput ohm reading as the stock coil on a 79 200sx. about .7 ohms. the point ones are about 1.4 1.6 ohms and when the key is back to ON it goes thru the ballast resisitor which is 1.6 ohms also.So a total of 3.2 ohms.

I bet the Jap coil is better in the 1st place!!!!!!MSD one just looks cooler


The Matchbox you get a hotter spart. and bigger point gaps. If you can get a Matchbox that is great but I have been satisfied with my Pertronix conversions.


Electric Fans are nice as seen on Jeffs Hinos 620 but a eleltric ignition should always come 1st just for relaibility. If you want cooler a 3 core rad is money well spent.

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im only talking about the electronic ignition, mike was saying you gotta have the coil to match the box (or maybe thats how i read it) the msd makes a huge diff, specially in how the truck runs, throttle response, and fuel economy. with pertronix, you dont need the ballast resistor, and with the match box you also dont need the ballast resistor.

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The Pertronix wants under 4 amps so a Ballast is needed and a Point resistant coil(1.4 -1.6 ohms. Its in the Pertronix instructions. Could cause a module failure. 12volt divide by 4 amps = 3 ohms total resitance.


A V8 guy at work had bought 2 Pertronix units. He burned them up using a Supercoil. I asked to you add a extra ballast resisitor? He gave me that Long starnge look. I havent burned up one yet. I installed about 5 so far.


But if possible the matchbox and MSD coil is a better setup if you can get one.(I have one as a spare)



Matchox usues a .7 ohm stock 200EI coil or a MSD is also .7 ohm coil.(Is it better?) I can never tell. when I swapped to a Supercoil from stock


I show this as a general rule as most KIDS run to the store and dont match stuff up then wonder why they are on the side of the road later.



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