Running like clockwork

Today I picked up the Datsun from Ken. He spent a lot of time checking everything and making adjustments. The good news is he said the engine appears very clean and the electricals/spark are great.

However, there were three main things he found wrong.

Firstly, the tappets were adjusted far too tightly. Whilst there’s a noticeable increase in tappet noise now, they are adjusted correctly and the valves will be opening and closing at the right times.

Secondly, carb 1 was receiving far too much fuel – all the time – due to incorrect plumbing of the vacuum. To cater for this, the carb had been leaned out on the adjustment screw. Ken said after he got the fueling right to the carb, he turned the adjusting screw out two full turns to get it right. This would also explain why plugs 1 and 2 were fouling on me, along with the choke sticking.

Thirdly, the oil pressure sender needs replacing. I’ll do this another time myself.

Above is Ken’s setup he used for testing carbs on an L18 engine.

The wagon is running like a dream now it’s setup and tuned correctly.

Air cleaner setup

I’m not happy with the look of the air-cleaner assembly. It’s also quite fiddly to remove and put back on. There must be something better.

I was Googling different setups and I found one I really like the look of:

K&N Circular filters, part # 56-9096 to suit L18 twin carb engines.

So I jumped on E-bay and ordered a set. Not particularly cheap at $231 for two, but should look awesome once installed.

I’ll do a write-up of the install once I receive them.

An expert tuner is found

By chance, I found out that a work colleagues father, now retired, used to have his own mechanic workshop and was an expert at old vehicles and carbs.

I gave Ken a call and arranged to drop my car off later in the afternoon at his residence.

In his large shed he had all the equipment from his old workshop, including a hoist, gas analyser etc. He even had a Datsun 180B engine in a frame with starter etc, that he could fire up to test carbs on! Amazing!

We had a lengthy chat about the Datsun and it left me in no doubt that I was talking to someone who really knows their stuff. Ken seemed excited to work on the Datsun as he hadn’t done one for a while. It’s a pity that blokes like this are rare now and not too long into the future, people with his skill will likely be gone.

Ken promised to go over everything, checking all the electronics, advance, tuning and balancing the carbs etc. It should be running like a dream when I get it back at the end of the week. Can’t wait!





A solution is found

After doing some reading and research online, I decide to remove the dashpots from the carbs, clean them and replace the oil.

The recommended oil for the dashpots is 10W-30. As I didn’t have any of that spec on hand, a quick trip to the servo and I purchased a one litre bottle of 10W-30 engine oil.

It was quite a simple process, the steps being:

  • Remove the air-cleaner(s)
  • Unscrew and remove the plunger (oil cap nut) from the dashpot. It should be coated in oil over the end of the plunger
  • Unscrew the 4 screws holding the dashpot cover (suction chamber) down and lift off
  • Remove the suction spring from the dashpot
  • Remove the dashpot assembly (sliding suction piston and jet needle), being extra careful not to damage or bend the jet needle at the bottom.¬†Note the reservoir in the centre of the piston should be full of oil.

I tipped the piston upside down into a jar and let it drain for a few minutes to get all the old oil out. The oil level seemed to be low and what oil there was seemed quite thick. I gave everything a clean and then it was time to reassemble.

Note the dashpot piston has a ridge on the side that lines up with a notch on the side of the carb. This ensures it can only be installed one way. Be careful to place the jet needle in the hole at the top of the carb.

What I did at this point was fill the dashpot reservoir with oil. Then place the spring over the top of the reservoir.

Now place the dashpot cover back in place, ensuring the spring goes over the centre receptacle inside the cover, screw back in place.

Before placing the plunger back in, we can check the dashpot piston is moving up and down freely inside the cover. The piston moves up and down in response to vacuum.

We do this by putting a finger inside the carb intake and gently lifting the dashpot. It should move smoothly and freely, but there should be some resistance, increasing as the piston rises.  Remove your finger and it should slowly fall back down. Both carbs should feel about the same with an equal amount of resistance.

Place the plungers back in and test again. You should note that there is more resistance now that the plunger is in place, but it still should operate smoothly.

Whilst I was doing this I was looking at and touching the linkages. I touched the choke linkage on carb 1 and it jumped back into place – it had been locked open again! Sprayed it with WD40 and gave it a clean to hopefully stop it sticking in future.

I gave the spark plugs a clean and fired her up.

The wagon has always taken a good amount of time before it will idle without choke and it takes a long time to get up to operating temperature.

Now, after a very short time it was idling nicely. I took her for a 20km drive and it was beautiful, driving better than it had done previously since I’ve owned the car. I was ecstatic to say the least.

I pulled the plugs and they were all looking perfect.

I took her for another lengthy drive the next day and she was still running perfectly. Interestingly, now the engine was getting up to operating temperature much more quickly, but it was also idling a little high when warm. So it looks like it might need some fine tuning, but it’s perfectly driveable now.