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4K carb tuning

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Hi all, I’m hoping someone on here can help me try and get my ke70 driving properly it’s a stock 4kc with 32/36 Weber and extractors running a returnless mechanical fuel pump. I’ve finally got it running and it seems to hold idle well but it has crazy rev hang. As well as this it is lurching and spluttering under load when around 2-3.5k rpms. I know basically nothing about carbys, coming from fuel injection. I know carbys have multiple circuits for idle, partial throttle and full right? In which case would it be the partial throttle that needs adjustment as it’s smooth at higher revs?


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Mate, its had it... beyond repair...  I'll take it off your hands...


Was that carb on a running car just before you bought it, or lying around for a year??

I've never fitted the Weber down-draught, but its still just a carb. If it has been sitting then muck builds up in the jets and in the drillings connecting them all through the carb. So strip it and clean it, or have someone do it. I hose it all out with petrol from a syringe, but a can of carb cleaner will do it. A rebuild kit would be good for pumps and gaskets if you can find one.

Write down the numbers stamped on every jet and hunt the internet for the sizes that people use. I've seen them but can't remember them. So long as yours are similar it should run, but if someone has already changed them and got it wrong, you might be in trouble.

Get it all cleaned inside and back together and see how it goes. Rev hang can be from a bent throttle shaft or similar, so make sure while its on the bench that it gives a clean 'click' when you close the throttle. Its common on DCOE Webers, but shouldn't be for DDs. 2000-3500 is when the idle circuit gives up and hands it all over to the main circuit, so see if that improves once its cleaned.

Here's a helpful pic for you...


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  • 2 weeks later...

Hey Jentriken I am also, thinking about going the Weber 32/36 you would not mind posting a picture of your engine bay so I can figure out what I need to remove, or is it basically keep dizzy advance and charcoal canister vacuum line and remove, old carby, vaccum lines, and EGR. But a Few photos of the engine bay would be nice which I can then use as Reference.

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