Backfires on shifting, muffler has a huge hole in it, Are the two related? Options

[gollygwagen]

I'm sorry to keep posting with silly newb posts, but I wasn't finding a clear answer. The car backfires sometimes when I shift gears and when I coast with it in gear. I think the second is likely related to the massive gaping hole in my muffler I plan to replace today, but if it wasn't I suspect that I will quickly blow a hole in the new muffler so I wanted to ask.

Car is coming together with all the stuff I replaced and next weekend I should replace all the fueling parts from the tank back and finish replacing the ignition pieces. After that it's mechanical and since it runs pretty well I'm thinking that's OK for now, just need to find the fancy oil this week. I know a local racing store carries Redline and Royal Purple products so I'll check with them today. How many quarts will I need and is the oil change interval similar to normal cars or due to it's air/oil cooled nature do you want to change it more often?

You guys have been great. I drove it to work for the first time today and saw three 911's on the short 7 mile stretch of highway I drive. Normally it's only Cayenne's, so I think it's a sign I'm on the right track.

[JStroud]

I'm no expert but it sounds to me like your timing is off. I would recheck your dwell and timing and see if that helps.....and patch the exhaust leak.
Good luck

Jeff

[gollygwagen]

I'm no expert but it sounds to me like your timing is off. I would recheck your dwell and timing and see if that helps.....and patch the exhaust leak.
Good luck

Jeff

I've got electronic ignition, so I don't believe I need to worry with dwell. But reading the Pelican article made me realize that the valves probably need adjustment as well as the timing. Every 3,000 miles! Wow!! So I better get good at this if I need to do it every oil change. Good stuff, I doubt the vavles have been adjusted in YEARS!