True backfiring (flames coming out of carburetor vs muffler explosions) is often plug wires out of order. Flame escapes cylinder when an intake valve is open. Could be timing but would have to be WAY off. Do a compression test to ensure valves are closing and sealing all the way. Muffler explosions are usually unburned fuel. Are you pre-detonating when engine is hot & under load? That was my problem. Try cooler plugs. And don't lug the engine -- with no RPM's AND vacuum dropped spark may come too late. What octane are you running? 91 factory spec was figured by some method other than what our pumps use (does it translate into 87 or 89?). I can not run reliably on less than 93. Re: adjusting main CO2 screw -- I've said 1000 times a rich mixture burns cooler than a lean one. Usually get shot down when I do, but I've got 3 melted plugs sitting on my kitchen counter right now that prove it! (Courtesy of a vacuum leak on that side of engine -- too much air for metered fuel, duh). What do your plugs look like? Bill Robertson #5939 >--- In DMCForum@xxxxxxxxxxxxxxx, "cruznmd" <racuti1@xxxx> wrote: > Walt, > > I'll tell you this; > > Fuel settings defintely have something to do with it because when I > richen up the CO screw it largely goes away. It doesn't just do it at > idle though. If I put enough of a load on the engine (toting uphill) > it does it. > > I'm starting to think you may be right about uneven delivery. > > I'm painting the engine cover not the louvers. I don't even have > louvers. They were cracked and snapped off and flew away a year ago > during the tow home. :( > > Mike does wonders with paint in a can, so it can be done. > > Rich > > > > --- In DMCForum@xxxxxxxxxxxxxxx, "Walter Coe" <Whalt@xxxx> wrote: > > Mike was telling me about your car backfiring through the intake. > The cause > > of this on my car was from one cylinder running too lean off of > idle. The > > injector for that cylinder was delivering about half as much fuel > as the > > others at idle, but above 1500 RPM it was fine. When I adjusted the > > air/fuel mixture, it caused that one cylinder to be too lean and > the other 5 > > to be too rich. Inspecting the plugs confirmed this along with > watching the > > injectors spray in test tubes. The problem with the faulty new > injectors > > must be that they are NOS and have rust in them. I'm curious to > cut one > > open and see. > > > > Having your timing off will also cause it to backfire through the > intake. I > > would have terrible luck trying to tune it by hear like Bill > suggests. > > There must be a procedure for setting/verifying the position of the > timing > > mark. > > > > > Question of the day: What is the best paint to use to repaint the > > engine cover? Bumper black or semi flat 1613, or what? > > > > I have never been too fond of any paint that comes out of a spray > can when > > compared to spraying real automotive paints through a spray gun. > Rich W > > painted the louvers of D-rex with Krylon Semi-Flat Black, and it > looks good. > > I'm curious to see how it holds up. Plasti-kote Bumper Black spray > paint (# > > 616) seems to be a spot-on match for the black part of the > fascias. I'm not > > sure how well it would stick to an engine cover, though. Like Bill > said, > > preparation is everything. If there is any residue of oil or Armor- > all or > > Back-to-black then you will get fish-eye in those areas. I have > seen too > > many painted louvers that are mostly glossy yet mottled with fish- > eye spots > > where residue made the paint go thin. > > > > Walt Yahoo! Groups Sponsor ADVERTISEMENT <http://rd.yahoo.com/M=194081.4074964.5287182.1261774/D=egroupweb/S=170512 6215:HM/A=1732161/R=0/SIG=11p5b9ris/*http://www.ediets.com/start.cfm?code= 30509&media=atkins> click here <http://us.adserver.yahoo.com/l?M=194081.4074964.5287182.1261774/D=egroupm ail/S=:HM/A=1732161/rand=916638192> To unsubscribe from this group, send an email to: DMCForum-unsubscribe@xxxxxxxxxxxxxxx Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service <http://docs.yahoo.com/info/terms/> .
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