My engine starts very easily and runs very smoothly and has plenty of power! So what’s the problem?
The problem it that after it starts and after I rev or drive it for a short time the idle speed goes up and runs way too fast, probably about 2000 RPM.
I went to a car show in my town a while ago and asked a chap there who had an older car where I could find a good engine tuner, someone to work on my carb, he referred me to Russel in Caloundra, so I went to see him but he refused to work on my 40 year old car because it was not old enough, and because he was busy, and he like working on the older classic cars.
He was friendly and we chatted for a while and I described my problem with the high idle. Russell suggested the flap was sticking open and that I might try a bit of INOX Lanoline Oil to loosen it up.
I pressed him for more information and I asked if he used some “Special Engine Sauce” to clean out his Carburettors, he showed and he showed me a can of ThreeBond Engine Cleaner and warned me that although it loosens and cleans, it leaves behind a residue which will harden if left, so I will need to flush flush all the residue away before it hardens again.
I washed out the Carb with the “Special Sauce” and then liberally washed the inside of the carb with petrol and a paint brush and now it is sparkling clean inside. Prior to cleaning my carb was black inside and now it is silver !
I did server things, with the engine idle I sprayed the inside of the carb, and then let it sit for a while with engine off, and then I washed if for with petrol and a paint brush Then I sprayed it with the engine running to get deeper in the carb and washed it out with petrol and a paintbrush. till all the bit I could see were sparkly clean.
This has fixed the high idle speed, I suspect it was a sticky flap, and my guess it that it was probably the second flap which gets stuck open when the van runs fast and uses more power.
The engine idles so smooth and so slowly now that the oil pressure light comes on, so I just need to set the idle a little higher. If I just tap the accelerator very lightly the pressure light goes off immediately
I was wondering if any knows of a book, document or PDF explaining how a carburettor works, and how to properly tune a carburettor?
The Nissan E23 Z20 Engine is very similar to the Datsun 720 Engine
Datsun 720 (Episode 6) – Carb Rebuild