Brian, I have the engine and carb setup as you describe, but without any problems.
I was about to suggest you install one of the very inexpensive digital temperature sensors in your carb air box , ahead of the carb, as I have. They are cheap ( $10-15 ) and the remote sensor can be riveted to the box floor for security.( picture on request) One strange effect that I have noticed with this sensor installed as mentioned , is that when carb heat is applied partially , is that the temperature in the box goes DOWN initially , not up as expected, due I suspect , to a venturi effect , past the flapper valve. Again , my set up is almost identical to yours ( minus the K&N filter , which I just bought , and was planning to install.). Currently , I have a lawnmower type , flat paper , filter. Not sure if this info helps but for what its worth I think the temp sensor is a good idea and may help you understand what is happening better. Regards Chris Gardiner C-GKRZ 2180VW GPAC , Zenith 1821 carb ----- Original Message ----- From: "Brian Kraut" <eng...@earthlink.net> To: "Harold Woods" <audreyandharoldwo...@rogers.com> Cc: <kr...@mylist.net> Sent: Tuesday, October 21, 2003 6:34 PM Subject: KR>Re: rough engine. > > First of all, thank to everyone that has offered suggestions. > > > > A lot of people have remarked that it may be carb ice. I don't think > it is because I get an RPM increase even sittting on the ground at > full throttle when I pull the carb heat half on. This is in Florida > in 85 degree temperatures and relatively low humidity for this area. > The engine also immediately picks up RPM when the heat is pulled and > immediately looses it when it is pushed back in. > > > > Now maybe there is some problem with this carb not atomizing the fuel > well unless it is heated a little. If that is the case I would > suspect that someone else would have seen this problem in the past. > > > > I do plan on ordering an EGT to be sure the mixture is correct and see > if it changes when the carb heat is pulled. I will probably also > order a mixture indicator from [1]http://www.halmeter.com/. This uses > an O2 sensor in the exhaust. I also will be adding a MAP gauge and > may even try a temporary Radio Shack temp probe in the carb while on > the ground to see what kind of temps I have. > -----Original Message----- > From: Harold Woods > Sent: Oct 21, 2003 4:31 PM > To: Brian Kraut > Subject: rough engine. > > Hi Brian > > Sounds to me like a classic case of carb ice. > > It may be Florida and 85F on the ground which gives you a high > humidity. Go up to 8500 feet and the temperature is much lower but the > air still has the same weight of water vapour in it. As it is pulled > through the carb the temperature falls further, the water condences > and freezes. You get carb ice. > > Add enough hot air to melt it and keep it from reforming, adjust the > mixture to suit and you have solved the problem. > > Regards > > Harold Woods > > Orillia,ON.Can. > > [2]haroldwo...@rogers.com > > > > --- > Outgoing mail is certified Virus Free. > Checked by AVG anti-virus system ([3]http://www.grisoft.com). > Version: 6.0.522 / Virus Database: 320 - Release Date: 9/29/2003 > > References > > 1. http://www.halmeter.com/ > 2. mailto:haroldwo...@rogers.com > 3. http://www.grisoft.com/ > _______________________________________________ > see KRnet list details at http://www.krnet.org/instructions.html
