So drive 300mile round trip to bug n Jam in bus . On a couple of occasions when decelerate had a back fire whats cause ? Anything worry about ? Sent from my SM-S901B using Tapatalk
Check for leaks in the exhaust system before worrying too much. In my experience poorly fitting joints on the exhaust system are usually highlighted by an occasional backfire.
^^^ as said. If it is a Type 1 motor the best answer is to put a flange kit on. Should have been done by VW from the get go. Best single modification you can do
Some pre-drilled cut out metal shapes, and a welder. Look on Ebay. Or if you get the good quality exhaust clamps, smear some exhaust paste on them, and the same with the tin gaskets going to the cylinder head and any heat riser pipes.. (or use reusable annealed copper gaskets), you should not have too many problems with air leaks in the exhaust without spending lots of money. The other reason for a good backfire can be a loose wire in the ignition, or point gaps closing up causing you to rotate the distributor too far to get the timing right , so the rotor arm is not pointing properly at the correct peg in the distributor cap, then the spark sometimes "cross fires" to another plug.. Or with a Weber progressive the carburettor rotates and the choke power wire shorts out on the fan housing killing the ignition for a moment.. In each case, the effect is for unburnt fuel mix to enter the exhaust where it gets ignited by the first exhaust pulse that is hot enough. Unless you have a rusty exhaust, the bang is mostly for show, and in some kiddie car exhaust systems, there is a spark plug for the purpose. If your exhaust is a bit old, the explosion can make a quite large hole then it has an air leak, may pop some more....
As said, bits of pre drilled steel. Aircooled.net use to sell them. The dia of the hole is different as one fits over the j tube / HX pipe and one fits over the exhaust pipe (one slides into the other normally)
You can see the bottom flanges on my exhaust system One the 2nd pic, you can see one flange on the RHS and the left one has not been put on yet
That is what happens when 2 blokes, a carton of beer, a welder and too much VW knowledge have nuffin to do on the weekend
