73 620 Project

[Zomgturbozombiejesus]

Picked up a 73 620 yesterday, while it runs and is drivable - there are a few issues I want to get ironed out before I start doing any legitimate driving around.

 

Brakes: Basically you have to pump the brakes if you want the car to stop at all (even then its a touch on the dicey side), I'm hoping that this will be fixed by bleeding the brakes and changing the shoes. I do have a 78 suspension in my garage that has front discs, how tough is it to swap - and is it worth it?

 

Clutch/Tranny: Currently has the stock 4speed. The friction point for the clutch is pretty much with the pedal 98% out. Even when the car is in gear if you give full throttle the rpms will shoot up as if you were depressing the clutch, but if you give it 1/3 throttle the rpms climb steadily and you actually accelerate. I'm assuming this means the clutch is on its last leg and I might as well replace it. If I do that I feel like I might as well swap the tranny out with a 5 speed (presumably from a 280? I've found some other posts regarding which 5 speed to use, still need to finalize that info). If I'm doing this what other stuff should I do while I'm at it as far as seals and bearings go.

 

Oil leak: I'll post better pictures later, but there is an oil leak that is or was seemingly spraying oil around the oil filter. Going to clean the whole thing up and do an oil change to determine where the leak is coming from.

 

Electrical: After driving it home I turned the truck off and the radiator fan was still running. I know it runs off the thermostat so I figured it would shut it self off when the temperature returned to normal. I came out several hours later and the fan was still running and the battery was almost dead. With the key out of the ignition the CD player still turns on as well, going to need to look into that. As far as the fan that kept running what would cause that? bad thermostat?

 

Fuel leak: There is a slight crack between the fuel tank and the filler hose, only leaks when the tank is 100% full - easy enough to fix.

 

Man when you write it all out like that seems like this thing is falling apart, but it's not so bad.

 

Here are some quick pics until I get some good ones up:

 

 

[Skib]

welcome to Ratsun :cool:

 

nice user name :lol:

 

 

 

ratsun is a brothel of picture whores so youd better get out there and take more pics before they start chiming in :rofl:

[Zomgturbozombiejesus]

ratsun is a brothel of picture whores so youd better get out there and take more pics before they start chiming in :rofl:

 

More pics:

 

 

 

 

 

 

 

 

 

 

 

 

 

Here is said oil disaster:

 

[pharouh]

Nice truck! Love the wheels!

Same year as mine.

Welcome to ratsun!

Oil leak...Hmm maybe front seal or front cover gasket?

Why does it have an electric fan? Where's the stock fan blade?

Sadly,the front suspension swap with a 78 is not a bolt on. The mounts are different. There are disc conversions available in the parts for sale section. Very nice stuff.

Brakes-yeah try bleeding them and see what that does.Check the shoes,too.

 

good luck!

[dat620]

welcome, and yea what he said, must have an electric fan conversion, all 620's came stock with a fan/clutch type cooling fan set up, as far as it running after ignition off, could be faulty temp sensor, bleed the brakes and as you said ck the shoes, oil leak at filter is sign of filter gasket to tight, and gasket got pinched, sounds like hercules did the last oil change, all very minor stuff, and you may as well change out the tranny, you gotta pull it to change clutch any ways...nice score, even if it need s a little tlc, they all do. :cool:

[74datsun620]

Welcome to Ratsun!!!! Cool 620!!!

[Zomgturbozombiejesus]

Ok, so I've decided this thread has been dormant long enough. The truck has been sitting in my driveway since I posted this and I'm finally getting the time/money to start getting this show on the road. Currently since the car has been sitting it won't start. The electric fan killed the battery, which I tried throwing on a trickle charger but no dice its fried. I got a new battery as well as oil change supplies and spark plugs. I was going to go ahead and snag some new ignition wires and a fuel filter as well as some new drums and shoes all around. When I bought the car the dude said if it ever doesn't start I need to check the points, and when I bought it from him it started on a dime every time. So I'm a complete n00b when it comes to distributors. I have the Haynes manual for the truck, but gaping the points doesn't seem to be particularly straight forward, nor does the chapter seem to tell the measurement of the gap. I've searched around the forums but didn't really find anything helpful. Any tips? Also I found a 5 speed from a 280zx on craigslist, dude wants $150 that seem fair?

[Zomgturbozombiejesus]

Also transmission is from a 1980 non turbo 280zx, that should bolt right up correct?

[yellowdatsun]

Yep.

[kneesamo]

Your stock distributor was a dual points style, don't know what that gaps supposed to be for those, and I think the single points wanted 0.020", but a rule of thumb (side of the road fixing method) is the thickness of the cardboard from a matchbook.

 

If the contact surface of the points looks charred, or isn't very flat, you can use sandpaper or a nail file to clean them up, just remove the points first.

 

A quick method of checking the points, is to have someone crank the motor(or you can use the old screwdriver to the starter trick), and with distributor cap off, you can visually seen if the points are opening or not. Or you can turn the motor by hand, you'll have to turn it by hand to adjust them anyways.

 

To adjust them you turn the crank until one of the lobes of the distributor shaft, reaches it's apex, and opens up the points. Then you loosen the lock screw, turn the adjustment screw until the desired gap is achieved, and then tighten the lock screw. Very simple.

 

If you drive the truck abunch, you'll get to do it alot.

[Zomgturbozombiejesus]

Thanks for the info guys. I was able to find the distributor air gap on the L16 is 0.018-0.022 in, so basically 0.020 was right on the money. Found lots of quick L series info at http://www.olddatsuns.com/620tech.htm

[Zomgturbozombiejesus]

So I adjusted the gap on my points tonight but still no dice. Not having done this before I advanced the motor until the cam on the distributor until the breaker arm hit it at the highest point and the gap was pretty dead on .020 inches, it snugly slipped inside, so its well within the .018-.022. I put the cap back on then tried to start it up and no dice, just cranks and cranks. It was starting on the first or second crank every time before I let it sit for six months. What should I check next? The surface of the points looked clean, as well as all the contacts on the cap and wires. I haven't pulled out the plugs yet, but I imagine they wouldn't get fouled just sitting there. Maybe the gas has been sitting too long?

[mike]

Are you getting spark at all? Pull your plugs and check them... for spark and cleanliness, if the points had a habit of going bad they could very well be fouled. Do you have a test light or multimeter to see where youre getting power in the electrical system? Also, http://www.olddatsuns.com//620tech.htm Check this site out, theres factory service manuals down towards the bottom of the page. Theres a good troubleshooting section in them.

 

If you plan on driving it alot you should ditch the points and get an electronic matchbox distributor, someone here has probably got one they will make you a deal on. Makes life way easier :cool:

 

150 for a ZX trans isnt a bad deal, Theyve got a tall overdrive that will work well with your gears. Youre going to have to shorten your driveline though. It would be a good time to have a one piece drive shaft made so you can ditch the carrier bearing unless you can find the front half of a driveshaft from a 74 or later standard cab 620 (thats when they switched to a longer transmission the same length as the ZX 5 speed)

 

Also on your oil leak check your pan gasket, Clean up the engine compartment before you do an oil change, if it is your pan gasket youll save an extra oil change, that stuff isnt getting any cheaper... It will stay cleaner longer after you clean all the shit out of the bottom of your pan too.

[datzenmike]

Also transmission is from a 1980 non turbo 280zx, that should bolt right up correct?

 

No. Well yes, it will bolt to the motor but you will need to shorten the drive shaft and modify the transmission mount. OR: The tranny mount, speedo cable and front half of the 2 piece drive shaft from a '74 and up 620 should convert this over. Keep and use the release bearing collar that is on your truck now.

[DanielC]

Here is a simple trick to help you with points. Take a test light, and ground one side. Now, go turn the key on. Touch the probe on the test light to the negative side of the coil.

When the points are open the light should be on. When the points close, the light should be off.

 

If the light stays on, either the points are not closing, or you are on the wrong side of the ignition coil. Try the other side of the coil.

If the light never comes on, you are not getting power to the coil.

[Zomgturbozombiejesus]

Didn't have a lot of time to work on the truck this weekend due to working on the nursery, but I did change out the plugs - looks like they needed it.

 

 

Didn't help my starting issue, but it needed to get done anyway. Also drove about an hour out to pick up this 5 speed tranny.

 

 

I have a drive shaft from a 78 620 - from above responses I should be able to get it working with that? I'll pickup a test light and multimeter this week to try and solve my starting issues. I figure I'm going to need those anyway to try and find what's draining the battery when the truck is off. It seems like the previous owner wired the radio and 6 disc changer to power instead of accessory because they will turn on even when the key isn't in the truck. I have to figure out how the electric fan is wired as well. Also the truck had a manual choke installed at some point, going to check that out to see if its still functioning or what the deal is.

[Zomgturbozombiejesus]

Should have some time to work on the truck this weekend. I have a weber carb on its way as well as a matchbox dizzy. The distributor needs a new rotor and cap as well, and I'd like to upgrade the coil while I'm at it.

 

Also the seller said the carb has been sitting for a bit and recommended it be rebuilt, are there any preferred rebuild kits for the 32/36 dgav? Also am I going to run into any issues since there is a manual choke currently installed, obviously I just disconnect the line that goes out the switch in the cabin, but why would the previous owner have done that in the first place? Inability to tune the stock carbs reliably?

[]2eDeYe]

 

I have a drive shaft from a 78 620 - from above responses I should be able to get it working with that?

 

That should do it.

 

 

 

Also am I going to run into any issues since there is a manual choke currently installed, obviously I just disconnect the line that goes out the switch in the cabin, but why would the previous owner have done that in the first place? Inability to tune the stock carbs reliably?

 

SHouldn't be an issue. He probably did it to save a couple $ over the electric choke.

[Zomgturbozombiejesus]

Well look what we have here:

 

(Ignore muddy dog footprints on floor)

 

Thanks to schicksal for the quick responses and shipment.

 

I have a rebuild kit on its way, so I'll jump into that once it arrives.

 

I had a little bit of daylight to burn when I got home from work so I decided to try and see why the truck isn't starting. I pulled the stock air filter and disconnected the line that comes from the fuel pump to the carburetor and put the business end into a beer bottle (which was mysteriously empty). I jumped in the cab and cranked it ten or twelve times; checking the bottle afterward there is zero fuel making it from the pump to that line. I know the truck has an issue with the filler neck leaking when the tank is full, but I was told that was only when it was completely full (there is a tiny hairline crack where the neck meets the tank where it leaks). At any rate I went under the assumption that the gas gauge was incorrect and possibly the fuel had all leaked out of the tank. So I added about 2 gallons of gas to the tank and retried but I'm still not getting any fuel out of that line. The fuel filter is also empty. I assume since its cheap the easiest way is to change out the filter, which I will do this weekend, but is there a way I can tell if the fuel pump isn't doing its job?

[datzenmike]

Didn't have a lot of time to work on the truck this weekend due to working on the nursery, but I did change out the plugs - looks like they needed it.

 

 

Three look ok but the top one doesn't. Did you keep track of what cylinder it's from?

 

 

Didn't help my starting issue, but it needed to get done anyway. Also drove about an hour out to pick up this 5 speed tranny.

 

 

Can't tell if it's a 5 speed, it's upside down.

 

 

I have a drive shaft from a 78 620 - from above responses I should be able to get it working with that? I'll pickup a test light and multimeter this week to try and solve my starting issues. I figure I'm going to need those anyway to try and find what's draining the battery when the truck is off. It seems like the previous owner wired the radio and 6 disc changer to power instead of accessory because they will turn on even when the key isn't in the truck. I have to figure out how the electric fan is wired as well. Also the truck had a manual choke installed at some point, going to check that out to see if its still functioning or what the deal is.

 

Disconnect the radio and disc player. If you still have a draw, remove one of the battery terminals and connect a test light across them. Pull fuses one at a time to find out which fused circuit the problem is on.

 

Things that can drain the battery without the key on:

Brake lights

Interior lights

Horn (horns disconnected but the relay stays on)

Headlights/parking lights

Bad alternator

Bad regulator

[Zomgturbozombiejesus]

Cool, I'll get to that once I get it started. Since the pump didn't seem to be pushing any fuel I added some into the carb via the fuel inlet and tried starting it up. It turned over once then died. Trying to decide if I should stick with getting it running before installing the new carb and distributor.

[DanielC]

Get it running first. And then change only one thing at a time.

[mike]

On your fuel pump, pull the line going to the carb and put it in an empty bottle, and pull the line coming from the tank with your fuel filter on it and stick that in a bottle with some gas in it, crank your motor over a couple times and see if youve got fuel coming out... If its working you will know quickly. If its good, check all the rubber and metal lines on your fuel line all the way to the tank, if you have a significant enough crack, it will suck air instead of fuel.

 

Whats the odds that all the electrical add ons (fan, stereo and whatever else) are somehow tied into your ignition system? ...Ive seen some crazy things when it comes to prior owner electrical "fixes" Check the wiring diagrams on olddatsunpickups...

 

If you get a matchbox distributor make sure that you get the pedestal with it, it will save you a bunch of headache, otherwise you will have to get creative to get your engine to time in correctly.

[Zomgturbozombiejesus]

So I did the test Mike suggested, I didn't start behind the filter I just bypassed it. I think the filter is bad, or the lines behind it because its got absolutely no fuel in it. The pump did its job and pulled the fuel from my makeshift tank out where the carburetor inlet would be. So the pump is working, but it appeared to be leaking gas - at the very least it was pretty soaked with gas after I ran the test. Even after I confirmed the pump was working I placed the carb inlet line back into the carb and put the intake and air filter back on. Truck sounded like it was turning over once or twice, but then it just dies.

 

On a separate note, thanks to jefe de jefes matchbox came in the mail, still need to order a cap/rotor and a new coil.

 

Also someone asked for a different angle pic of the trans I got last week.

[mike]

If your pump IS leaking gas its bad... make sure that its not seeping around the hoses or that you didnt spill some. If youre sure it leaks, swap her out...