i have a random question for anyone who may know.

when i clean the inside of my carby (stock 30 pict) with carby cleaner the revvs drop and it splutters a bit and u have to work the throttle arm to stop it from stalling when u are cleaning it. then of course it goes back to normal when u are done.

however a couple of weeks ago (this has been playing on my mind) i was doing the same to a freinds datsun 120y with a 14a engine and as u spray the very same carby cleaner into the throat the engine revs increase dramatically, to the point where u need to spray small amounts at a time to stop it revving so high!

can anyone explain this?

Nicko

[ Edited on 24-4-2007 by Anthiron ]

its all air/fuel ratio. if you have the original restricted inlet manifold the carby cleaner was probably flooding it(thats why you had to use the throttle to let more air in). whereas the 1400cc nissan inlet manifold was able to flow more air into the engine to compensate for the extra fuel.just my 2c

mate that carbie cleaner is fantastic for cleaning everything ,especially stuff like sikaflex ,i had it all over my hands today and just gave it a quick squirt and off it comes ,probably not the best thing for you but what is these days

not Danielle here, but I was having a look and thought I could help out

I'd say that the datto was running extremely lean at idle, because if like the beetle, its running properly at idle, the carby cleaner will richen the mixture up causing it to stall (and probably puffing clouds of black smoke too) but if the datto is running lean at idle, the throttle has to be adjusted open to compensate for less fuel, when you spray the cleaner it corrects the mixtures and idles high.

the datto is probably also idling like a hairy dog, but seems to be OK on full power?? Danielles beetle had the same problem last time she was driving regularly. to clear it out, (this is so exciting) with the air cleaner off, give the car a decent rev. and while holding the throttle wide open, put your hand flat over the top of the carby (your hand will get sprayed with fuel being sucked out the jets) the revs will die down but dont let your hand off the throttle, when the revs drop significantly, probably to around 1500 or so, take your hand off the top of the carby, but hold the throttle wide open still. it will probably cough and splutter for a while and blow copious amounts of black smoke, but the revs will soon start to rise, and when its revving cleanly again, whack your hand back over the top and suck some more fuel through the syastem.

that will usually clean out any crap in the idle circuit. it may also have a fuel shutoff solenoid, that should have power any time with the key on, and will cause the same issues.