My carb is killing me.

[Mattyou72]

Alright I have a 81 Datsun 720, it's got a number of problems. I've decided to tackle the carb first. The previous owner puts a Webber but held onto the original carb and passed it to me when he sold it. So I gess the question is, original or after market, because both need to be rebuilt.

[Draker]

Weber would be easy to rebuild... but lets face it.. sometimes they are just worn out paperweights. 

 

Open it up, clean it out. Put it back together.. if it runs like shit. Just toss it. 

 

I've never rebuilt a stock hitachi.. But you can get kits for them. They are more complex.. but same principals still apply.

[LenRobertson]

Webers have less parts than the stock Hitachi so should be simpler to rebuild. Unless there is something missing or damaged (like the throttle shaft having a lot of free play in the carb body) the Weber it is probably the first choice for rebuilding.

 

A Weber on a Datsun usually (maybe always) has an adapter plate between the intake manifold and the carb base. It is possible for the adapter to loosen up resulting in a vacuum leak. Before tearing the carb apart it is worth wiggling around on the carb and see if everything feels snug. Then with the engine idling spray carb cleaner around the carb base and adapter plate. If there is a gasket leaking the engine sound will change as it gets a whiff of carb cleaner.

 

Carbs do get gunked up so I;m not saying you don't need to go into yours, but I would make sure everything else is good first - plugs, timing,valve adjustment, fuel filter, replace all vacuum hoses if they show any sign of cracking at the ends, maybe plug wires and cap (although these are usually not bad). Not to advocate randomly throwing money at it, but check everything over and see how it looks.

 

Len

 

 

[flatcat19]

Why do people spray carb clean on an engine for diagnosis?

 

Spray brake clean. Less damage to other parts.

Carb clean is lethal to rubber and plastic parts.

[Draker]

Propane works

[datzenmike]

Weber is likely the easiest because it has half the parts. The Hitachi will be more work but the better over all runner. Mileage, drive ability, emissions. In both cases dirt is the most likely cause of problems as there are few moving parts to wear out. Dirt on the outside can stiffen and seize some moving linkages too. Last are some of the adjustments like float level and the choke un-loader.