Lachlan's 1972 Datsun 1200 Sedan

[datsunfreak]

1 hour ago, Lachlan said:

Here's a shot of it just after it died. I'm happy with that.

 

 

I am a little concerned about all that wetness around the base though? 

[Lachlan]

Had a break from working on the car which coincided with a busy September.

 

Over that time:

 

- Picked up garage racking for use as storage and work bench

- Fixed a friend’s zero turn mower

- Spread chicken poo all over the lawn and fragranced the neighbourhood

- Found somewhere else to store and use my ride on mower

- Travelled over 1000km / 620mi through the central & north west of NSW

- Still fixing driveability issues with my wife’s daily after the big trip

- Borrowed a friend’s ultrasonic cleaner to clean the multitude of carbs under my care

 

I’ve driven the 1200 a few times over that period and there’s definitely still an issue with the air/fuel mix or fuel delivery until it gets fully warmed up.
 

On 8/30/2023 at 10:38 PM, datsunfreak said:

I am a little concerned about all that wetness around the base though?

 

As much as I wanted to avoid it, I think another carb rebuild is called for. It was in my inexperience that I decided to rebuild it the first time well before the rest of the car was ready, so it sat for two years and likely gummed up the passages and needles again. At least I’ve got the right cleaning equipment now.

 

Also there’s a knocking coming from the front left of the car near the wheel area which I haven’t located yet. More investigating to come.

 

Question: How do you stop the speedometer cable connection in the trans from leaking? I’ve heard you only snug it up and in the disassembly of the original I didn’t see how the plastic seal inside was oriented. Any ideas?

Edited October 11, 2023 by Lachlan

[datsunfreak]

23 hours ago, Lachlan said:

As much as I wanted to avoid it, I think swapping in a Weber carb is called for

 

Fixed it for you.  😁

 

23 hours ago, Lachlan said:

Also there’s a knocking coming from the front left of the car near the wheel area which I haven’t located yet.

 

Check the ball joints and tie rods. If you did not service/replace them before driving it, they are likely now bad.

 

They get dry from sitting, and seem fine when you first drive it, but then grind themselves into dust as the kilometers stack up. 

 

23 hours ago, Lachlan said:

Question: How do you stop the speedometer cable connection in the trans from leaking? I’ve heard you only snug it up and in the disassembly of the original I didn’t see how the plastic seal inside was oriented. Any ideas?

 

You mean other than swap in a manual trans?  😁

 

Unfortunately, I am pretty sure the transmissions you guys got in the auto cars is not like ours, especially if yours is an Aussie-assembled car. 

 

FWIW, I usually go a little farther than just snug and use pliers to tighten it a bit more. 

 

I know our autos here in the US were impossible to make them not leak at least a few drops here and there. The early USDM cars had Borg-Warners (I think somewhat similar to the AUDM auto trans) and the late cars had a slightly better Jatco. Only the Jatco could be made to leak less. 😄

Edited October 12, 2023 by datsunfreak

[Lachlan]

40 minutes ago, datsunfreak said:

On 10/12/2023 at 8:25 AM, Lachlan said:

As much as I wanted to avoid it, I think swapping in a Weber carb is called for

 

Fixed it for you.  😁

I laughed a lot at this! Well played. 👏 I’ll explore a swap after exhausting the capabilities of the stock Hitachi as everything is setup for it. It goes really hard once warm, it’s just that initial warm up phase that’s causing issues. A thorough clean should do the trick.

 

41 minutes ago, datsunfreak said:

Check the ball joints and tie rods. If you did not service/replace them before driving it, they are likely now bad.

 

They get dry from sitting, and seem fine when you first drive it, but then grind themselves into dust as the kilometers stack up.

Great call, I will start there. In the pursuit of registration, I forewent changing any parts that weren’t called out in the safety check. I think you’re right that they’ve gone cactus. Came on so quick and loud too. Thanks for the tip!

 

44 minutes ago, datsunfreak said:

You mean other than swap in a manual trans?  😁

 

Unfortunately, I am pretty sure the transmissions you guys got in the auto cars is not like ours, especially if yours is an Aussie-assembled car. 

 

FWIW, I usually go a little farther than just snug and use pliers to tighten it a bit more. 

 

I know our autos here in the US were impossible to make them not leak at least a few drops here and there. The early USDM cars had Borg-Warners (I think somewhat similar to the AUDM auto trans) and the late cars had a slightly better Jatco. Only the Jatco could be made to leak less. 😄

Haha, I hear that’s a worthy upgrade. The A12 has more pep higher up which would be easier to explore with a manual.

 

This 1200 has the JATCO 3N71B and is mostly leak free as I dropped the pan, changed the filter, gasket and fluid. I’ll nip up the speedo cable and see if it helps. It does have a Borg-Warner diff though.

[datsunfreak]

18 hours ago, Lachlan said:

This 1200 has the JATCO 3N71B 

 

Very good. 👍

 

18 hours ago, Lachlan said:

It does have a Borg-Warner diff though.

 

If you ever need to repair it, or just want a Hitachi/Datto unit instead, I am pretty sure the 1200 utes down there had them. The later utes (80s+) should be the bigger H165 with 4.11 gears. 

[Lachlan]

On 8/14/2023 at 2:53 PM, Lachlan said:

Question: How do you lift the cold start revs when there’s no fast idle adjustment on the carb?

 

I have a manual choke Hitachi DCG-306 with only curb idle and fuel mix adjustments. The owner’s manual suggests full choke with a single to-the-floor push & release of the accelerator before starting. It starts fine but quickly starts to chug unless you push in the choke a bit and compensate with additional accelerator input.

I finally have an answer to my own question.

 

After pulling the carb once again, it was completely dismantled, treated to multiple carb cleaner showers and ultrasonic baths, given fresh tailored gaskets and sealed up tight. The first start was laboured until fuel flowed freely through the jets once more. It kicked to life and … died. Still needed more manual throttle. That was the whole point of the exercise. Defeated!

 

That is, until I remembered I’d sourced a Mazda training PDF in my travels that covered this exact carb as it was also on the 323. I quickly flicked through it and yes, throttle adjustment with manual choke. Turns out you simply bend the connecting rod to add more throttle when the choke valve/plate is closed.

 

This video really shows it best. Look at the bent rod that links the choke movement with the throttle movement (from 0:25 in video). The throttle needs to come on earlier and have more input at full choke.

 

 

I won’t have time to experiment until tomorrow but I’m confident that a gentle straightening of the connecting rod will solve the cold start issue and improve driveability.

Edited November 1, 2023 by Lachlan

[RyanC]

Nicely sorted hope it's running better when cold now.

[Lachlan]

On 12/29/2023 at 12:20 AM, RyanC said:

Nicely sorted hope it's running better when cold now.

 

It's definitely better that it was. I also discovered that the best way to cold start is:

 

1. Press & release accelerator once (or twice)

2. Pull choke all the way out

3. Press & hold accelerator halfway down

4. Turn key

5. Let it fast idle for about a minute until the engine note changes e.g. slight chugging

6. Gradually push choke in tiny increments to maintain smooth fast idle

 

If I touch/blip the accelerator or push the choke in/out, it seems to reset the fast idle. I can get it back if I hold the accelerator at halfway then push in and pull out the choke again.

 

For some reason, having the choke on and holding the accelerator halfway down allows the carb to hold a higher rev setting than if you either:

 

- Start with choke and no accelerator pressed, or

- Start without choke and accelerator halfway.

 

I know you didn't ask but I thought that might be helpful for someone else with a manual choke carb and no fast idle screw.

[Lachlan]

On 10/13/2023 at 7:54 AM, datsunfreak said:

Check the ball joints and tie rods. If you did not service/replace them before driving it, they are likely now bad.

 

Nailed it - ball joints were the culprit. I'd parked it for a while to work on replacing the seats and came back to this recently. After a brief test drive, the clunking was worse than ever so I pulled into the garage and had a much closer look. I noticed grease had escaped from the lower ball joint boot and tried refilling it with more. After a couple pumps it started escaping again, so I wiggled the boot around and noticed a big crack in the metal part below the rubber. Time to replace (both sides).

[Lachlan]

The seats installed in the car were terrible and had to go. I'd bought some used MX-5 (Miata) seats a couple years back and it was time to install them. I knew this would take me a while as I've not done much metal fabricating but it was fairly straightforward. What follows is many hours work measuring, remeasuring, test fitting, making templates, remeasuring, cutting, filing, remeasuring, drilling, test fitting, etc. I've still got to paint the brackets to finish it off. I used 10.9 spec high tensile bolts into 40 x 40 x 2.5mm square tubing to ensure strength in an accident.

 

Original seat rails.

 

 

MX-5 seat base.

 

 

Brackets.

 

 

Installed in the car.

 

 

I think they look great in the car.

 

 

 

[datsunfreak]

16 hours ago, Lachlan said:

The seats installed in the car were terrible and had to go. I'd bought some used MX-5 (Miata) seats a couple years back and it was time to install them. I knew this would take me a while as I've not done much metal fabricating but it was fairly straightforward. What follows is many hours work measuring, remeasuring, test fitting, making templates, remeasuring, cutting, filing, remeasuring, drilling, test fitting, etc.

 

Same seats I had in mine!  😄

 

16 hours ago, Lachlan said:

think they look great in the car.

 

Yes they do. 👍

 

I ended up removing my stock rear seat brackets and mounting the seat behind the rail to get them 1" lower. At 6'3", they didn't work great on top of the stock rails. 😋

 

16 hours ago, Lachlan said:

 

Nailed it - ball joints were the culprit. After a brief test drive, the clunking was worse than ever so I pulled into the garage and had a much closer look. I noticed grease had escaped from the lower ball joint boot and tried refilling it with more. After a couple pumps it started escaping again, so I wiggled the boot around and noticed a big crack in the metal part below the rubber. Time to replace (both sides).

 

Do future you a favor and do the tie rod ends while you have it apart, if you haven't already. 😉

[RyanC]

22 hours ago, Lachlan said:

 

It's definitely better that it was. I also discovered that the best way to cold start is:

 

1. Press & release accelerator once (or twice)

2. Pull choke all the way out

3. Press & hold accelerator halfway down

4. Turn key

5. Let it fast idle for about a minute until the engine note changes e.g. slight chugging

6. Gradually push choke in tiny increments to maintain smooth fast idle

 

If I touch/blip the accelerator or push the choke in/out, it seems to reset the fast idle. I can get it back if I hold the accelerator at halfway then push in and pull out the choke again.

 

For some reason, having the choke on and holding the accelerator halfway down allows the carb to hold a higher rev setting than if you either:

 

- Start with choke and no accelerator pressed, or

- Start without choke and accelerator halfway.

 

I know you didn't ask but I thought that might be helpful for someone else with a manual choke carb and no fast idle screw.

Most chokes create a fast idle and the blip will reset it.  The main thing is it starts when cold.

 

Those mx5 seats look good.  I had thought they would work nicely in the ute as they are slimline.