Lachlan's 1972 Datsun 1200 Sedan

[Lachlan]

Thanks @datsunfreak and @datzenmike.

 

My guess is the answer lies somewhere in between.

 

16 hours ago, datsunfreak said:

...which is the correct/only answer. 👍

 

 

Sounds like someone is experiencing their first old car with a manual choke and super basic carbie.  😁

 

Haha, yeah you're probably right. Though I know it used to start and warm up much better on full choke before I rebuilt the carb. I did set the float when reassembling, however, it seems as though I got the setting wrong. @slowlearner heard it running on the weekend and without prompting said it sounded like it was running rich.

 

15 hours ago, datzenmike said:

Spray, and while holding throttle slightly open, work the choke on and off. Work all linkages till they move freely by their own weight.

 

Great tip, thank you! I tried getting in there with some silicone spray while the air cleaner was attached but couldn't really get to where I needed to. I've now taken the air cleaner off and will give all the moving parts a thorough lubricating.

 

Do you recommend any lubricant other than silicone spray? I use that when I'm unsure what to use. Maybe white lithium spray grease?

[Lachlan]

I'm growing in certainty that there's no fast idle feature on this most basic manual choke version of the Hitachi DCG-306. It seems like it has four ways of adjustment:

 

1. Choke adjustment    --  Checked

2. Curb idle screw        --  Set

3. Fuel mixture screw  --  Set

4. Float level                --  Too high!

 

There might be more, but they seem the most relevant. There are no vacuum assemblies attached to this carb.

 

Going with the idea that it could be the float level setting that's causing it to run rich during warm up, I set about removing the top of the carb. The relatively new gasket (2 years old) tore right away, so we're off to a good start. I'll cut a new one.

 

I also recorded this video of the throttle being full pressed and released, followed by the choke set on full and released.

 

 

[datsunfreak]

On 8/14/2023 at 11:42 PM, Lachlan said:

I'm growing in certainty that there's no fast idle feature on this most basic manual choke version of the Hitachi DCG-306.

 

I am also fairly certain it does not.

 

I have used these on B110s, B210s, and B310s, all because they are simple and reliable. 

 

But they are very sensivitve to air leaks and improper float levels. 

Edited August 16, 2023 by datsunfreak

[Lachlan]

On 8/16/2023 at 3:53 AM, datsunfreak said:

But they are very sensivitve to air leaks and improper float levels.

 

Thanks for your input @datsunfreak. I'm wondering about those two things after having spent the better part of last night and today cutting a new gasket, setting the float level, reassembling everything, testing, pulling it apart and repeating again. I'm chasing what I think is an air leak that wasn't there before I popped the top of the carb.

 

Here's the 'correct' method I used to set the float level two years ago and again today.

 

NOTE: I am using the larger 11.1mm measurement as opposed to the recommended 10.5mm as that's what it was previously set at which didn't work.

 

 

This isn't a particularly useful photo but because it was so hard to capture with a phone I'm posting it here just because.

 

 

Another way suggested by a different source is to turn the carb top on its side and gently angle it towards the right so it just touches the needle.

 

 

Here's the gasket I cut. Not bad for a first effort.

 

 

Could the fact I used a paper style gasket instead of the traditional rubber cork style be a cause of air leakage?

 

 

I did horrific and unspeakable things in the pursuit of eliminating presumed air leaks.

 

 

In the end I seem to have failed. Before a good long drive, but after it was warmed in the driveway, I couldn't get the car to idle below about 1000rpm without stumbling and running the fuel mix screw out. It definitely wasn't like this before. All I touched was the float level and gave all the accessible jets a good blast with carb cleaner and cleaned up the gasket faces.

 

This was the wet (running) float level when I had to stop.

 

 

Still looks too high to me. The second adjustment today (third in total for me) has it set closer to 12.5mm.

 

Where to from here? Do I locate a rubber cork gasket and try again? I'm learning to listen to the car and it sounds unhappy. Don't ya hate when you go to fix something and you make it worse?

 

PS What image sizes do you guys use? I'm oscillating between 800x600, 1024x768 and 1200x900.

Edited August 20, 2023 by Lachlan

[pdp8]

If you are still getting too high a fuel level, I'd be worried that you needle and seat could be leaking.

Degraded viton, a small sliver of teflon tape or other foreign object could both cause leakage.  If not a leak there, are you *sure* there's not a leak in your float (shake it and see if it sloshes).  Excessive fuel-pressure can also cause this, but it takes an electric fuel pump to manage that.

[Lachlan]

Appreciate the great suggestions, @pdp8!

 

I had the same thought about the needle and seat last night. A year ago, I acquired a push mower that would drain its fuel tank via the air filter thanks to a failed needle and seat. If memory serves, when I rebuilt this Hitachi carb two years ago I didn’t replace the needle and seat as the replacement in the kit was the wrong type.

 

Regarding the float, there’s a small chance this one could be leaky given its age and behaviour. I haven’t found any cracks or pinholes, nor has it been sloshy when I’ve removed it having run it hours earlier. Might park that for now given the likelihood of the needle and seat being the issue and the difficulty finding a replacement float.

 

Still running a mechanical fuel pump so no issues there. Hopefully!

[Lachlan]

Found a replacement needle and seat on clearance and it’s being transferred up from Sydney through a parts store’s network. Also located a nearby store with 1.4mm cork rubber gasket material to give that a try for the carburettor top instead of the gasket paper. I’m sure the gasket paper was probably fine but I want to eliminate any sources of air leakage.

 

This little A12 will run sweet when I’m finished chasing the issues.

[datsunfreak]

11 hours ago, Lachlan said:

Also located a nearby store with 1.4mm cork rubber gasket material to give that a try for the carburettor top instead of the gasket paper.

 

Good on ya! You may also try rubbing it down with some wheel bearing grease. Make them seal a bit better, be less crack prone, and be able to be removed without breaking later on (if need be).

 

11 hours ago, Lachlan said:

This little A12 will run sweet when I’m finished chasing the issues.

 

Side question: I know rego can be a bit draconian there, but what are the rules concerning switching to something like a Weber 32/36 carbie? 

 

Speaking of dead simple and easy to tune (and new!).

 

 

 

[RyanC]

You've been busy Lachy.  Hope you sort out that carb soon.  I've never played with that one.  My current Webber 32/36 was new to me as well so plenty to learn. 

 

Sounds like the auto is all sorted.  I'm assuming idle mixture is variable? 

 

Timing set etc?

[Lachlan]

48 minutes ago, datsunfreak said:

You may also try rubbing it down with some wheel bearing grease. Make them seal a bit better, be less crack prone, and be able to be removed without breaking later on (if need be).

Great tip, thanks! Would this be better/worse than using a thin layer of Permatex Sealant Liquid?

 

48 minutes ago, datsunfreak said:

I know rego can be a bit draconian there, but what are the rules concerning switching to something like a Weber 32/36 carbie?

You just sent me down the rabbit hole! There’s been so many posts on Webers for A12s - very cool. They are completely new to me and the thought never crossed my mind. If I were really stuck and the stock Hitachi was toast, I’d be ordering the conversion kit.

 

I’m not 100% sure, but I don’t think there’d be any rego issues with a carb change.

 

26 minutes ago, RyanC said:

You've been busy Lachy.  Hope you sort out that carb soon.

Thanks! I’m working at getting it solid for use as a daily.

 

26 minutes ago, RyanC said:

Sounds like the auto is all sorted.  I'm assuming idle mixture is variable? 

 

Timing set etc?

The auto is much better now! I tweaked the vacuum modulator and it shifts later (and harder) than before without the smoke show. Will adjust it slightly lower next time I’m underneath.

 

Hitachis on Australian models have only the (a) idle speed and (b) idle mixture adjustment screws. The only other adjustments are float level and choke butterfly operation.

 

Timing is currently set at 8 degrees. I’ll tweak this when the issues upstream are sorted. I’m running premium 98 so I should have a couple degrees advance to play with.

 

Great questions and plenty to think about!

Edited August 21, 2023 by Lachlan

[datsunfreak]

4 hours ago, Lachlan said:

Great tip, thanks! Would this be better/worse than using a thin layer of Permatex Sealant Liquid?

 

In my experience, much better. 

 

4 hours ago, Lachlan said:

Timing is currently set at 8 degrees. I’ll tweak this when the issues upstream are sorted. I’m running premium 98 so I should have a couple degrees advance to play with.

 

FWIW, I have routinely run them at 11-12 on 93 octane. 👍

 

Do you already have an electronic ignition dizzy on there, or are you still running points? 

[Lachlan]

4 hours ago, datsunfreak said:

In my experience, much better.

I’ll give it a shot!

 

4 hours ago, datsunfreak said:

FWIW, I have routinely run them at 11-12 on 93 octane. 👍

 

Do you already have an electronic ignition dizzy on there, or are you still running points?

Excellent! I’m not familiar with how much you can push these engines before knocking, so that’s handy to know. On my wife’s daily with a similar setup (1.3L and 3-speed auto), it’s essential to dial in some more base timing or it bogs down on hills.

 

You probably know this but I only learned recently that that our 98 octane is similar to your 93 octane due to the different quality measurement across the world. Here’s a quick primer:

 

https://www.etuners.gr/fuel/

 

Still running the stock points setup. I haven’t adjusted them the whole time I’ve had the car. For now, I’ll leave it until I’m ready to make changes. I want to keep the variables to a minimum so I can better identify the cause of the issues. It’s hard to restrain myself from deploying the parts cannon at every problem but I don’t learn anything then. I know that’s not what you’re suggesting.

 

Is the electronic distributor an easy swap or a more involved change? Apart from less maintenance, are there any other improvements?

 

Because you all love pictures, here’s a somewhat stock 1200 engine bay:

 

[pdp8]

I can't speak to installing an electronic dizzy on the 1200, but I know all the later A-series motors use the same one.  You do want to use the newer coil as well to get the additional spark energy.

Expect better idle, easier starts, and just generally better running with an electronic setup. 

The biggest improvement was seen on my '67 Jeep where a shift from the mechanical setup made a huge difference in the whole character of the vehicle, but other swaps have all made a difference, just some more pronounced than others.

 

A swap to a smaller AGM or better still lithium battery will shave 20-30 Lbs off your car and do it up high and forward.  It's enough to feel in a 1200 particularly, brakes, steering, and power all improve.  Just saying....

Edited August 22, 2023 by pdp8

[datsunfreak]

16 hours ago, Lachlan said:

Is the electronic distributor an easy swap or a more involved change? Apart from less maintenance, are there any other improvements?

 

Super easy. Takes about 10 minutes. Just need to add one wire, set the timing, and go. 

 

10 hours ago, pdp8 said:

Expect better idle, easier starts, and just generally better running with an electronic setup. 

 

What he said. I don't want to oversell it, but the difference is night and day how much better it runs after the swap. Escpecially if you've never replaced the points. 

 

It feels like a jump of 10hp, easier starts, less plug fouling, etc. It is ALL upside, no downside. 

 

Also, the newer cap, rotor, and plug wires are easier to find new (at least here) than their old points counterpart. 

 

10 hours ago, pdp8 said:

I can't speak to installing an electronic dizzy on the 1200, but I know all the later A-series motors use the same one.  You do want to use the newer coil as well to get the additional spark energy.

 

You do want a newer coil built for electronic ignition, but you can get by on the stock 1200 coil for at least a few thousand KMs. 

 

I normally use an MSD Blaster 2 coil. Works like the stock style EI coil at a similar price, if you can't source a stock style unit. 

 

I don't know if they ship to down under addresses, but you can get everything you need from rockauto.com. Just order a distributor, cap, rotor, and coil for a 1980 Datsun 210. 

 

[RyanC]

Might sound silly because you seem to be all over it mate.  What RPM is she set at when warm/warmish?  Have you adjusted the idle mixture?  IF you can get it to warm up then run in till rough then back out till sweet is the general rule or the other way around.

 

I had issues with SU floats years ago on my 1600, ran her out of fuel and one cracked and was full of fuel so ran like shit, ordered new floats and it was much better.  I would adjust that timing up on 98 should be safe usually 11 to 14 on a L series but need to keep the ears out for pinging on 14.

[Lachlan]

On 8/22/2023 at 2:48 PM, pdp8 said:

Expect better idle, easier starts, and just generally better running with an electronic setup.

 

On 8/23/2023 at 1:38 AM, datsunfreak said:

It feels like a jump of 10hp, easier starts, less plug fouling, etc. It is ALL upside, no downside.

 

That sounds like a big improvement! Thanks for the heads up. I wonder if our local parts retailers stock any of that. We certainly had the B210 (called the 120Y here) so I don't see why not.

 

On 8/22/2023 at 2:48 PM, pdp8 said:

A swap to a smaller AGM or better still lithium battery will shave 20-30 Lbs off your car and do it up high and forward.

 

I remember you mentioning this much earlier in the thread. Weirdly enough, the car came with a healthy battery that hasn't complained once. I just kept it topped up as it sat for months and it always kicks. Once it's on it's way out, I'll shop for a smaller alternative as you've suggested. Add lightness!

 

1 hour ago, RyanC said:

Might sound silly because you seem to be all over it mate.  What RPM is she set at when warm/warmish?  Have you adjusted the idle mixture?  IF you can get it to warm up then run in till rough then back out till sweet is the general rule or the other way around.

 

I appreciate you offering advice - thanks! While I might look like I know what I'm doing, I've still got a lot to learn. I've only tuned EFI cars where the computer handles the fine adjustments, so balancing the idle speed and fuel mix is an added factor. I'm getting the knack the more I do it. You really can hear it sweeten up in the engine note.

 

Regarding your questions, prior to opening the carb up I could get it to idle nicely at about 800-850 RPM. After opening the carb to adjust the float and fit a new paper gasket, it now won't happily idle below 1000RPM. My best guess is there's either/both too much fuel entering the carb bowl by way of a faulty needle and seat and/or the paper gasket is not sealing effectively.

 

Which leads me to ...

Edited August 24, 2023 by Lachlan

[Lachlan]

My lovely wife picked these up for me.

 

The needle and seat were $6. I'd be foolish not to replace the existing one, especially since it's showing signs of failure.

 

The cork rubber gasket material just feels right. It's firm but should squish and seal the carb top nicely. I've probably got over a metre (3-4 feet) in that roll.

 

At least I'm getting plenty of practice cutting gaskets. And so we enter ... endgame.

 

Edited August 24, 2023 by Lachlan

[RyanC]

Yep so many times its poor seal or vacuum issues with carbs, fuel float settings etc  Hopefully it solves the issues.

[Lachlan]

Cut the second carb top gasket, this time from cork rubber material.

 

Top left is the gasket that was fitted when I bought the car.

Top right is from the rebuild kit that was fitted for two years.

Bottom left is my first attempt using paper material.

Bottom right is my second attempt with cork rubber material.

 

Old needle and seat is in middle of shot, new one was fitted when I took this.

 

Guitar picks are a great thickness for setting the float drop. Drill bits are useful for cleaning out holes in hand cut gaskets.

 

 

Gave the sealing surfaces and carb internals another good clean before refitting.

 

 

 

 

Here's the float wet level after replacing the needle and seat and resetting the float height back to factory spec. To say I was disappointed would be an understatement.

 

 

Here's the RPM and timing. At least it's now idling somewhat smoothly at 800 RPM. Timing is 7 degrees, right on spec. I haven't touched this at all.

 

[Lachlan]

On 8/24/2023 at 9:03 PM, RyanC said:

I had issues with SU floats years ago on my 1600, ran her out of fuel and one cracked and was full of fuel so ran like shit, ordered new floats and it was much better.

 

On 8/25/2023 at 11:17 AM, RyanC said:

Yep so many times its poor seal or vacuum issues with carbs, fuel float settings etc

 

@RyanC I think you might be onto something with the cracked float suggestion. Every time I've pulled it out it's seemed fine but I haven't really scrutinised it or given it a test in a saucepan. That will be the next step.

 

Was chatting with an older bloke at Cars & Coffee this morning and he suggested the same thing. Said to take it out, go to a quiet place away and shake it close to my ear. If any sloshing can be heard, it's got a leak. The 1200 wiki said the same thing. He also suggested putting it in a pot of boiling water and pushing it under the surface to see if there's any bubbles. I should be able to solder it up if I find a leak and after the fuel is removed.

 

Thank goodness people put their knowledge online because so much experience with the older style engines will be lost with the passing of the older generations.

Edited August 27, 2023 by Lachlan

[RyanC]

Yep pop under water and look for bubbles.  Or shake and listen.   If they are heavy they will just keep filling the bowl then leak to the jets.

[Lachlan]

On 8/27/2023 at 8:27 PM, RyanC said:

Yep pop under water and look for bubbles.  Or shake and listen.

 

Tonight I pulled the carb top yet again and removed the float.

 

Test 1: Shake near my ear and listen for sloshing. Couldn't hear a thing - PASS!

Test 2: Submerge in a pot of near boiling water and watch for bubbles. Couldn't see any - PASS!

 

 

Possible causes of too much fuel:

 

- Needle and seat not closing - REPLACED!

- Cork rubber gasket letting in air - REPLACED! - not really a cause though.

- Float leaking - TESTED!

- Fuel pump too high pressure - NOT TESTED - it's a mechanical New Old Stock Nikki and is unlikely to be the cause.

 

That leaves the only option of adjusting the float tang until I get the wet level to the middle of the sight glass. More trial and error to come.

Edited August 30, 2023 by Lachlan

[RyanC]

Well at least you can tick them all off.  Maybe adjust it significantly and see if it actually makes a difference.

[Lachlan]

33 minutes ago, RyanC said:

Maybe adjust it significantly and see if it actually makes a difference.

 

Great minds! I did just that and started it up only briefly as I live in dense suburbia. It was running rough which was to be expected as I'd made a large change to the baseline air/fuel mix. I couldn't get to the adjustment screws in time to stop it conking out, but I did notice that while it was running it was within 1mm of the centre dot on the glass.

 

That's a win in my book!

 

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

Edited August 30, 2023 by Lachlan

[RyanC]

Mate if the aim is the dot your on a winner there.  Hopefully it's a tweak of the idle mixture from there.