if your going to go into jet replacement I'd suggest soaking the carb in cleaner & a decent rebuild - new gaskets, set float level, etc... along with making sure its got the correct jets - carb kits should be cheap everywhere.

Hi guys


Very Urgent PLease !!!!!

Just removed a spark plugs and they were thick black, so definitely it is not doing proper fuel,
Just removed the carb and found some abnormal Jet sizes on it
as follows

Power Valve 50
Primary Main Jet 75
Secondary Main Jet 45
Main Air bleed primary 60
Main Air bleed Secondary 80

is this abnormal jet size configuration is the problem ? sugest me on this please since i am on the work now.

thanks
regards
sumith

yes that is a problem. The main jets you list are too small -- it should be running very lean and hot with white burnt plugs.

Which jets are you looking at? The main jets are on the bottom of the carburetor.

Main jets are located here, by removing these screws

Hi dd


Yes Those main jets were too small is it ?
Those are Primary 75 and secondary 45
do i go for factory size or little small ?
i don't know my carburator exact condition

But my Spark plugs were dark black and car was smooking on above 1000 higher rpm, that is what i was thinking why they did not become white shal i change my power valve too it is currently running 50 but factory size is 60


thanks
regards
sumith

Don't change the power valve, that won't be the problem. 50 or 60 is fine. The power valve ROD should be checked as discussed before and shown by the photos.

If you change the main jets, normally go 2 sizes different -- not 50 or 60 sizes.

For maximum fuel economy, use the factory sizes. They are sometimes fitted a few sizes LARGER for smoother operation.

Hi DD

I checked power valve plunger sometimes it get stuck in middle but very rarely, what can i do for it is removable or to do some oiling it a little?

thanks
regards
sumith

My advice is to replace that carburetor with a good used one.

Yes, the rod is removable. It is staked in, so it is tricky. Perhaps you can buy a new rod from nissan or maybe straighten the rod. Maybe lubricate it, I do not know.

I've never been able to fix a Datsun carb that had that problem. If the rod sticks, it allows fuel to pour through the carburetor via the power valve all the time. Normally this should only occur at full throttle. If the top gasket is torn or the top is warped the same thing occurs.

use stock jets put in 96 in the primary and 150 in the secondary mains.

But firstly as said before check if the top of the carburettor is warped I can almost guarantee it will be use a straight edge to see or if its bad enough remove gasket and just place in on the carb and you will see the side lift up.

You can remove the plunger with a small flat screwdriver their will be 3 small cuts around the washer base of it you can pry it out.

once you fix these then i suggest putting in the stock jets but fixing the power valve never worked for me kept sticking half way.

Hi Guys

Since last few days were holidays i was unable to buy stock size jets, But i had 75 and 100 and installed them for the time being , Lubricated the power valve plunger and washed with fuel and hopefully it will work for sometime, and cleaned all the jets and installed the carb and started it got started on first attempt and tuned the engine as good as i can ?
i drove it about 20 Km no problem at all and removed the spark plugs and checked ,
What do you guys and recommend me by looking at these spark plugs ? for me they are light brown color

thanks
regards
sumith

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The light brown color indicates very good burning.

Problem seems to be solved. Good work!