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620 engine bay


Jayc

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I bought my 1977 datsun 620 a couple of months ago and it is BARE BONE everything but the l20b block was in the engine bay and ive got it pretty much rebuilt but there are so many lines that i have no idea where they go. Does anyone have a stock 1977 620 A/T engine diagram i could look at so i can start piecing together the puzzle? HELP

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There wasnt anything there. It was bare bone but the block. Ive put everythingtogether just need the engine bay diagram so i know what lines go where. 

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Ill take some tomorrow in the morning. Just took the carb to get rebuilt so thatsgoing to be missing but it'll definitely help me explain the situation a lot clearer

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These are some of the things that i need help figuring out. I dont know where they go to and need help.....

If i knew how to upload a picture from my phone it'd help...

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20200509-151839.jpg 

 

Can be turned to face the rear. This is the coolant from the engine to the heater core. Show a picture of the firewall and the heater connections should be there.

 

 

20200509-151850.jpg

 

Fuel pump. Not stock so I assume inlet from the tank on left and to carburetor on right. There should be fuel hard lines across the front and back to near the carburetor and then back again for the fuel return to tank line. The threaded hole just to the left of the pump is where the ground cable from the battery goes. The strap for adjusting the alternator belt should be bolted onto the front not the back.

 

 

20200509-151857.jpg

 

Fuel inlet to pump at bottom. Fuel line from gas tank on left. Fuel return line should be the larger of the two. The one with the hose should go to a filter then to the pump. The clip holding the Red positive cable from the battery is actually for holding the heater return hose.

 

 

20200509-151929.jpg

 

Thermostat housing. Big hose to radiator top. Small pipe is by-pass hose connected down across front of engine to lower rad hose inlet. The pipe down across the front of the engine is missing. The brass fitting with the terminal is the temperature gauge sender with Yellow/White stripe wire on it. Fitting with Blue tubes is the EGR's TVV. The EGR is not shown near front of carburetor.

 

 

20200509-152033.jpg

 

Top pipe is the other end of the by-pass hose. Bottom pipe is the return from heater hose

 

 

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PS< The reason I asked, was because if you run a weber, and you can get away with it in AZ, you dont have to worry about all that EGR bs and it will have more power AND better fuel economy. 

But if you want to get it back to bone stock, invest in a good hardcopy of a haynes manual. It has diagrams for all the hoses. So many hoses.

Good luck and keep us updated. 

 

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It will probably give a slight increase in power over the stock carburetor but mileage will only be better if the old carb was in bad shape to begin with. Most Weber swaps are compared to a failed stock carb in need of a rebuild, so naturally the comparison is apples and oranges. The down side is the loss of thew stock air cleaner and it's built in air temperature control (ATC) valve which prevents carb icing in near freezing weather.

 

As for the EGR it does nothing but reduce emissions. It's not working at idle, during warm up and at full throttle so has no effect on performance if working right. If you don't want it, it's best to just disconnect the rubber hose to it to deactivate it rather than remove it altogether. Removal means making a block off plate which, besides looking home made and amateurish, can later have a gasket leak from poor rdesign and usually the 'builder' doesn't bother to tap it so they can keep a working PCV valve. This is a big no no.  

 

The Haynes manuals are ok. But they have to cover 7 years of truck, 3 engines, 4 transmissions, front disc and drum brakes, 7 years of electrical wiring and more. If you have a '77 go on line and get the factory service manual (FSM) for your year. It's twice the thickness of the Haynes and is devoted totally to your year truck.  

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alright so i actually just got back the carb going to throw it on in the next couple of days but since i dont have a heater core i need to plug the by-pass hose, return from heater hose and the coolant from the engine to the heater core. I cant find the metric size bolts for the bypass and coolant to heater core. and i dont know how i could plug the by-pass hose, return from heater hose.

Basically i just want to be able to get the thing running first, i figured i can put this things off until i get the 620 running. 

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Whats up Gene, just wanted to see if you knew how i could fix that heater core problem. i just need to plug the outlets but dont know what metric size plug i need and how i could plug the two outlets coming out from the bottom of the radiator hose outlet. i believe one is for the bypass and the other is for the heater return hose.  

@gene knight

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Just cut the two heater hoses to 2", put a suitable stubby bolts in the ends and hose clamps.

 

Not sure what you mean but do not block the bypass hose from the thermostat housing.

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8 hours ago, Jayc said:

Whats up Gene, just wanted to see if you knew how i could fix that heater core problem. i just need to plug the outlets but dont know what metric size plug i need and how i could plug the two outlets coming out from the bottom of the radiator hose outlet. i believe one is for the bypass and the other is for the heater return hose.  

@gene knight

Jayc: I got a z lower radiator hose outlet that didn't have the port that goes to the intake manifold piping and I ran heater hose from Port near rear of block back into the lower radiator hose outlet near alternator 

Edited by gene knight
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Gene, never bypass the heater core by looping the hose from the head to the lower rad hose fitting. This is hot water you are returning right back into the engine uncooled, in effect a 'short circuit' around the rad and putting an extra load on it. When the heater is shut off all flow stops so if you loop a hose be sure to plug it somehow. Shove a piece of wooden dowel in, anything that will plug it.

 

Z cars are EFI and don't need a warmed intake. 

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im not running a heater core system/blower motor in my 521 and i was given my current setup advice from a datsun guru here is phoenix who has been working on datsun for decades. plus i have barely any mileage / time on my rebuilt L18 motor with 9.5 to 1 compression ratio and has a rebuilt  U67 head and running a weber 32/36 carb. it was rebuilt in 2007 and i maybe have 300 miles driving/running time on it

Edited by gene knight
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Does it get hot in Phoenix in the summer. A lot of water can flow through that heater hose and that's a huge burden on the  cooling system. If the heater was working that hose would be shut off by the heater valve.

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13 hours ago, gene knight said:

im not running a heater core system/blower motor in my 521 and i was given my current setup advice from a datsun guru here is phoenix who has been working on datsun for decades. plus i have barely any mileage / time on my rebuilt L18 motor with 9.5 to 1 compression ratio and has a rebuilt  U67 head and running a weber 32/36 carb. it was rebuilt in 2007 and i maybe have 300 miles driving/running time on it

Your Datsun guru is wrong. Looping the heater hose like that disrupts the coolant path and can actually create a hot spot in the block because of the disrupted flow.

 

Race motors always have them plugged.

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10 hours ago, Stoffregen Motorsports said:

Your Datsun guru is wrong. Looping the heater hose like that disrupts the coolant path and can actually create a hot spot in the block because of the disrupted flow.

 

Race motors always have them plugged.

so what is your suggestion?

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