Hello.
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.
Kimmo