Most L engines will run on with either a downdraft or sidedraft SU carbies given the correct circumstances - the problem is that air, fuel and ignition are still present after the key is turned off but you only have to eliminate one of the ingredients to effectively stop run-on. I thought the stock L20B carbie has a fuel solenoid, may be not a stock carbie being used here. The terrible way that a Datto wired the ignition system so it can allow the coil to still get power when an IR Alternator eg Bosch is still charging after the key is turned off at above normal idle revs. To see if your Datto can do this you hook up a multimeter to the positive coil, give it a rev and kill the ignition and see if the coil loses power at the same time as you kill the switch - most don't. Fitting an ignition relay such as Toyota and Mazda use will stop this happening. Controlling air intake is a bit trickier but again a solenoid in the inlet manifold has been used by Nissan on some engines in the past to stop run-on eg Japanese 610 (L18SSS) with factory air. The solenoid lets all of the vacuum out of the inlet manifold when the Ign key is turned off - simple stuff i.e. no air, no run-on.
I've also seen some home grown concoctions that ppl have put together, some work, some don't. One that seems to work with SU's especially and I can't see why it wont work with a Weber 32/36 which are prone to run-on, is to use a vacuum controlled fast idle switch from an A/C Datto to set the idle speed, and you simply wind the carbie idle adjuster(s) back beyond the stall setting. The fast idle switch is activated by an ignition feed instead of an a/c feed and the level is adjustable. These switches are found on 180B's in the JY and designed to be used on solid throttle bars only i.e. not suitable for cable throttles. Have fun with it. regards Terry -----Original Message----- From: [EMAIL PROTECTED] [mailto:membersozdat_owner@;datascribe.com.au]On Behalf Of Paul Stanley Sent: Thursday, 17 October 2002 8:00 PM To: [EMAIL PROTECTED] Subject: Re: Engine wont stop Funny you should mention that because my Datto misses steadily at low RPM, but not at cruising speed... I'm thinking it's the leads. But when I back off, the exhaust pops and crackles quite a bit and a friend said that that is a sign of GOOD compression. So I have conflicting theories here. If I were to diagnose it I would say that my carby is stuffed giving the misses and the crackling, and I have carbon buildup in the cylinders, and the fuel is probably getting into the cylinders too hot maybe, causing the engine to keep running after it's switched off. From: Paul Stanley [EMAIL PROTECTED] ----- Original Message ----- From: James Cox <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, October 17, 2002 11:59 AM Subject: Re: Engine wont stop I used to have the same problem on my L20B as well, I think it is a sign of low compression, have that checked, you may be up for some new rings. James Cox >What's it called when you switch the ignition off but the engine continues >to run, sometimes even doing quite a fair few rpm BACKWARDS? > >My stock 200B (apart from extractors, and ram flo air filter) does it >unless >I allow the engine to run for about 10 seconds at idle before switching it >off. What causes it? Is it worn carby needles or something? If it's the >carby, should I get a carby kit or by a whole new carby from the wreckers >from a newer L20 engine and just bolt it on? > --membersozdat------------------------------------------------------- OZDAT Mailing List Please Note:- Send (un)subscribe requests to [EMAIL PROTECTED] Send submissions to [EMAIL PROTECTED] No unauthorised redistribution of this email http://www.ozdat.com/ozdatonline/index.htm http://www.ozdat.com/ozdatonline/listindex.html http://www.mail-archive.com/membersozdat@;datascribe.com.au/ ---------------------------------------------------------------------
