One cause of rough running that I haven't seen mentioned is a sticking exhaust valve. This is very common on A4s and easy to address by fogging the engine with Marvel Mystery Oil. With the engine running, pour a small amount of MMO into the air intake. Repeat a few times and it will usually free up the valves. James Taylor S/V Delaney C&C 38 (with A4) Oriental, NC
On Tue, Apr 13, 2021 at 4:57 PM Lee Goss via CnC-List <cnc-list@cnc-list.com> wrote: > Just wanted to send a quick note to say thank you for all the wonderful > advice in this thread. > > Looks like i've got a decent project to keep me going until the habors > open on May 1st! > > Thanks again, > Lee > > C&C 29 MK.1 > Lake Michigan > > On Tue, 13 Apr 2021 at 11:24, Dave S via CnC-List <cnc-list@cnc-list.com> > wrote: > >> Have stayed out of this A4 thread for a variety of reasons, however based >> on plenty of work over many years with carbureted engines I second Bruce's >> emphasis on making sure that the fuel supply and carb are verified as a >> priority, before proceeding to other more complex causes. (steps 1-4) In >> my own experience this is where the trouble usually lies in engines that >> are not in regular use. Will also second the carb overhaul >> recommendation.. Carb rebuild kids are usually cheap, the job is pretty >> straightforward, and gaining confidence in and and familiarity with the >> fuel system is well worthwhile. >> >> Dave 33-2 >> >> On Tue, 13 Apr 2021 at 08:44, Bruce Whitmore via CnC-List < >> cnc-list@cnc-list.com> wrote: >> >>> Hi Lee, having had an Atomic 4 for 15 years, I can say the 2nd video >>> sounds largely normal once you got it starte. So, it seems yo tell me >>> compression is OK. The first one sounds a little rough, like a fuel >>> issue. That could happen if the engine was run all the way out of fuel ans >>> you had limited filtration of the gas. At any rate, out of an abundance of >>> caution, I would do the following: >>> >>> 1. Get a compression gauge and check for even readings across all >>> cylinders. >>> 2. Clean the fuel strainer bowl. >>> 3. Overhaul/clean the carb. You probably won't even need gaskets, and >>> they're simple to do. Just be sure that you take photos as you take it >>> apart and count the number of turns as you remove the adjustable jet(s). >>> Tighten the counting the turns, and when you put them back in, go to tight >>> and back out the same number of turns. >>> 4. If you don’t have one, put in a fuel filter/water separator. It >>> doesn't need to be a racor, one with a spin on filter (about $25) is fine. >>> 5. Convert to electronic ignition. Moyer has a kit, but the same model >>> is available elsewhere. Replace the cap and rotor while you're in there, >>> as well as the plugs, which are Champion RJ12Cs. The cap, rotor and plugs >>> are available at auto parts stores once you look up the Delco numbers. >>> 6. Replace the raw water impeller. If the engine sounds weird to you, >>> it may be the engine isn't pumping water through it like it used to. That >>> is a wear item and should be replaced every 2 years anyway. >>> 7. Add StaBil and SeaFoam to your fuel. A dose of Marvel Mystery oil >>> doesn't hurt either. >>> 8. Carry a spare coil. Once you go to electronic ignition, you'll >>> probably never need it, but it is a potential point of failure. >>> >>> They're very dependable engines once you know what makes them tick (or >>> not). >>> >>> Bruce Whitmore >>> 1994 C&C 37/40+ >>> "Astralis" >>> Madeira Beach, FL >>> (847) 404-5092 >>> >>> >>> Thanks to all of the subscribers that contributed to the list to help >>> with the costs involved. If you want to show your support to the list - >>> use PayPal to send contribution -- https://www.paypal.me/stumurray >>> Thanks - Stu >> >> Thanks to all of the subscribers that contributed to the list to help >> with the costs involved. If you want to show your support to the list - >> use PayPal to send contribution -- https://www.paypal.me/stumurray >> Thanks - Stu > > Thanks to all of the subscribers that contributed to the list to help with > the costs involved. If you want to show your support to the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray Thanks > - Stu
Thanks to all of the subscribers that contributed to the list to help with the costs involved. If you want to show your support to the list - use PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu
