Aircooled VW South Africa

Hey guys,

Need a bit of advise (excuse my use of non technical terms). I have a '75 Beetle 1600 that is giving some problems. It has a severe backfire and for that an obvious loss of power. I have had a new carb, coil and distributor put in but the theory is at this point that the reason is because of a warn plug socket. Apparently it is not sealing properly and drawing air.

My question(s):
1. Is this a known problem.
2. What would the best fix be (besides a new head)? So, I was told to drill out the hole and put a new recoil in???
3. If a new head is the only way, where is the best place to shop for this?

Thanks

A common cause of backfires on overrun, coupled with power loss, is a burned valve. No3 is the usual culprit. The cause is failure to adjust valve clearances every 5,000km. When the tappet gap closes, the valve doesn't completely close at operating temperature, which causes burning.

A lean fuel mixture can also cause backfiring on overrun, coupled with overheating of heads and burned valves. Holes in the exhaust can also cause backfiring (effectively leans the mixture).

You may indeed have a loose plug with damaged threads, but I don't see how that can cause the symptom. A loose plug or leaks at the plug will cause a champagne cork popping or chuffing sound inside the engine compartment.

A compression test will tell you on which cylinder the problem lies.