backfireing

[The_Handier_Man1]

From: tommys73winn  (Original Message)
Sent: 4/13/2008 5:27 PM

my winny set up for about 3 mounths without being cranked.it wasnt geting gas so i replaced the fullpump.it cranked up and ideled bad i reset the idel it smoked but ideled good.then i ran around the block in it half wayaround the block it got slower and slower then not staying cranked.then it finely got around the block and died in the driveway.tryed to crank it back up then it backfired .cranked it up agin backfired thes hapend 5 or 6 times.i swiched carbs still doing it.pepole in my neborhood thinks im shooting a gun. the engine is a 413 in a 73 cheftain



From: Cooneytoones
Sent: 4/14/2008 2:58 PM

Sound to me like the timing is not advancing...the plates and springs inside the distributor may have a little rust on them if some moisture got in it while sitting. Clean the points, ot get new ones,  get an new condenser and cap...make sure the wires were not accidently switched around.....and that the plates down inside the distributor are moving freely...if not, a little machine oil (3 in 1 oil works good or even some WD-40 put on the plates and springs.

If it has electronic ignition just lubing the plates may help....also, make sure your vaccume advance hose does not have a hole in it and it is in the correct port on the carb.

A problem I had is when I replaced a cap once, timing would not advance...drove me crazy until I looed down inside the distributor...a little brass button from inside the old cap fell off and was keeping the plates from moving....those plates have to move freely in order for the timing to automatically advance as you speed up.... it will backfire like hell when they don't move.

Let usa know what you find.

Timmy



From: tommys73winn
Sent: 4/14/2008 6:27 PM

thanks for the info ill try it as soon as i get home tomorrow.i love the thing and would like to go more than a block one day.



From: tommys73winn
Sent: 4/17/2008 1:59 PM

tryed it but nothing changed .know i cant get it to crank.its geting gas to the carb and the plugs are sparking do u think its the coil going bad?



From: Cooneytoones
Sent: 4/20/2008 7:28 AM

It sure sounds like a timing issue.....It could be a bad coil....what carb do you have installed. If it is a thermo-qaud, backfiring could be caused an internal leak in one of the carbs bowls. But I think you said you changed carbs.....try changing the coil. Is it elctronic ignition or do you have points?

Timmy



From: tommys73winn
Sent: 4/20/2008 10:11 AM

it has electronic ignition and a 4 barrel holly.im thinking the coil allso but i took a plug wire off and put in a nother plug and it was sparking fine.tryed a notherholly carb that i had no change.ill try the coil nextweek if thats not it then ill try to see if the timeing chain has slack in it thats all i can think off. thanks 4 the info it does help alot



From: denisondc
Sent: 4/20/2008 5:39 PM

Is it backfiring (up through the carburetor) or out through the exhaust (afterfiring)? The afterfiring is caused by unburnt fuel in the exhaust system that gets ignited by the flame coming from the engine the next time it 'fires'. This usually means the mixture is wayyyy too rich, and probably some of the spark plugs are fouled too. It can also be cause by valves that are sticking and not closing fully. The sticking valves are more likely to happen on an engine that gets run without being fully warmed up and run for a while on the highway. A possible cure for that would be to pull the rocker covers off and squirt oil onto the valve stems, and let it soak-in overnight.



From: tommys73winn
Sent: 4/20/2008 7:36 PM

it is afterburning,so ill try it tomarrow wene i get in from work.butt its allso puffing smoke and makeing a simi loud hissing sound out off the carb butt ill rebuild the carb for that one.its mainly sounding like a shotgun from the tailpipe. thanks 4 the info will let u know how it works



From: denisondc
Sent: 4/20/2008 9:14 PM

A loud hissing from the carb is normal if the air cleaner is off. The air cleaner is also the air intake 'muffler'. If the smoke from the tailpipe is black, thats from being too rich. This can also happen when the carb is letting it too much fuel, such as when the float is stuck to the bottom of the float chamber, or something is caught in the needle valve and the float cant close that valve.
Some blue smoke from an old engine that hasnt been run on the highway for weeks or months is also fairly common - so a film of blue smoke may just be a sign that it needs to be run on an over-the-road trip of 30 miles or longer. Mine always gives off a think blue stream when we start off, after it has been sitting for months. Its always cleared up after 30 to 60 minutes of driving on the highway though.