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Datsun L28 carburetor main jets

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The car is a 280C 4D Hardtop with L28 and Hitachi carburetor.
I cleaded the carburetor parts and all looks very nice and untouched, but im not anymore sure which sides/ways the main jets comes.
The original factory parts catalog tells that the primary jet (size 132) goes to the bigger canal where the vacuum controlled powerflap is. (outer side).
And that secondary jet (size 200) goes to the engine side, for smaller canal with gas and choke flap are.
I suspected that there can be a mistake in the factory catalog.
So which ways these usually goes? The jets are with the same thread and outer dimensions.

The problem in the car is that it keeps carbon fouling the plugs. All plugs has an even color.
Black smoke and carbon comes from exhaust, and also the exhaust sounds like a pig, misfiring. Too much gasoline for engine.
The car has new plug cables, new points and condensator, distributor cap had small corrosion, after cleaning came clean.
Coil is measured and also tested with a new cheap one, no effect.
Vacuum lines are checked and looks good.
Gas lines and tank are cleaned, with new filter before electrical pump.

Before the carburetor cleaning, the old plugs seemed to have a normal color, but must be noticed that the car has been unused for over 10 years.
I already tested to swich the main jets other ways, but then it seemed the car ran too lean and had backfire throught carburetor. Also the rews with choke on were around 2500rpm.
But still the exhaust was sounding like a pig.

Its a little annoying, since there are no technique simple as this and its still a little mysterious.


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All Hitachi I have worked on the jets are marked for size and the larger jet 200? goes on the vacuum operated secondary side or the larger opening and the smaller 132 primary goes to the smaller primary barrel with the choke flap. Basically larger opening needs larger jet.


On cold start up the choke will be on and it will rev to 1,800-2,200 RPMs to speed the warm up. Within 8-10 minutes the choke should warm and turn off and the idle can be reduced to 700-800. When the choke is on it will run very rich but if driven after warm up the plugs will self clean themselves.


Carburetors can backfire if the engine is cold even with the choke on. Was the engine cold?


Can you post a picture of this L28 carburetor? All our L28s were fuel injection.

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Thats what I suspected. So the parts catalog is wrong as seen in photos below.
I just need new spark plugs and should be fine then.

The engine was cold when backfiring, but the sparkplugs were also fouled already because of rich mixture. The idle adjust screw was also 5-6 turns open, so it was very lean.
Under the idle adjust, I found another mixture screw that was sealed. I use this in tune up and seal it again. This screw was 8 1/2 turns open.

Here are the photos of the carburetor and car itself.


This car is brought to Finland from Saudi-Arabia. The finnish versions of the Cedrics were mostly with LD28 engine since 1980.

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By the way, one thing on the car is weird to me.
The air-conditioner turns on when turning the switch to BI-level. Is this normal?
The BI-level setting is also in a car, that dont have air-conditioner.

This car has dual-AC, which means that the rear passangers can tune their own unit.

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In the diagram part 61 is in the way so it's hard to see where 33 and 34 lines go.


The idle mixture screw (set and sealed at the factory so owners won't mess with it) only adjusts the idle mixture. Make sure the engine is thoroughly warmed up and the choke off. Idle speed screw set so it idles at around factory idle 700? Turn mixture screw in (leaner) till idle quality drops, turn out (richer) till quality drops. There may be a 1/2 turn where idle becomes faster and stronger so set roughly in the middle. Turn idle speed down and repeat in and out looking for the strongest/fastest idle. Continue the in and out till you cannot improve the idle quality and the idle is what ever the factory recommends, probably 700 or so. Idle mixture only adjusts the idle has no effect on driving.


Backfiring when cold can happen. Called a lean backfire. The gas has to vaporize in order to mix with the air and burn. When cold it will act lean and this is why a choke is needed. It forces an over rich condition but may still backfire till warmed up. Just drive slower with less throttle for 5 minutes.







Primary jet to the left and secondary to the right, above





We didn't get the Cedric but I've seen a few imported later ones. I guess early '80s? We did get an L24 810 and Maxima.



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The car seems to work now pretty well. I still have to fill the AC if I find a place that has the old stuff.

Yes, I have keep wondering why they didnt get Cedric's to Usa. I would have been suitable there.

In here it was a common car in Taxi use, almost all that was brought here went for Taxi.
Soon the taxi drivers found out that these 430 and Y30 models were super strong, even from inside. You cant get the seats bad if you don't do it on purpose.

This is the Finland / France model of Nissan Y30 Cedric. Still in original factory condition, like new. Only 430-thousand kilometers. LD28 with automatic transmission.
I made a vintage style taxi-setup for it.


And the Datsun 430 (280C) Cedric.
At this photo they are making honour for a killed taxi driver by driving in line.

But still under the salesname of Datsun, the sheet metal had really bad quality. It got little bit better for Nissan in 84 and 85, and still better for 86. It does not rust so easy anymore.
_medium.jpg _medium.jpg
Like a hardbread.

Cedric and Laurel.

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Yes the Laurel. Was the Cedric ever available in 2 door??? or estate car?? (we call them station wagons) Does it have a solid rear axle or IRS (independent rear suspension) It looks about the size of our 910 Maxima which also came in LD28

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The Datsun 280C had wagon brought in Finland.
Nissan Y30 had wagon aswell, but not brought from Nissan. We have some pieces of these but someones brought those seperate from Russia. They usually were with V6, but was swapped to LD28 inside of Finland.

All Cedric's were 4-door cars.

Rear axle is solid.

In front, 280C had upper and lower arms, and Y30 got Macpherson.

Y30 also got a newer version of the LD28, which had better water canals and some more differences like belt lines etc.
Injection jets were smaller and a different setup at pump. Made the car slower, but usually Taxi's screwed it a little to get more power or speed.
Some installed 280C jets.
Y30, we had opportunity to buy with VG30 engine aswell, but only around 50 was sold. 4 of them was in a Taxi use. One had 600 thousand driven in 3.5 years.

The best LD28 kilometers I know was 1.6 million kilometers without opening the engine, so with a right service, its a technic that never seems to broke.

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And the Laurel C32 had RD28 engine.

This car has little over 1-million kilometers, but the head is made 3 times. Transmission is still untouched and works like new. Will restore this car, since of nice Taxi history in Helsinki and so much kilometers.

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