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.

[kevin311]

Sounds to me like an exhaust leak. Put that new muffler on and (IMG:style_emoticons/default/driving.gif)!!
I would bet the old one rusted through, I maybe wrong but there would have to be a major blockage in the muffler to build up enough pressure to blow a hole.

[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]

Sounds to me like an exhaust leak. Put that new muffler on and (IMG:style_emoticons/default/driving.gif)!!
I would bet the old one rusted through, I maybe wrong but there would have to be a major blockage in the muffler to build up enough pressure to blow a hole.

I was just going to swing by the muffler shop over lunch, but now I'm tempted to order up the Bursch unit from Pelican. Anyone have recommendations? I currently have an aftermarket one on (what's left of it) with dual exhaust and I'm thinking I would like the classic single tip look. The only downside is that I have my lift tied up with pulling the tranny out of my main car. It will probably take me a week to get that done. :-(

[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!

[wingnut86]

I have a brand new Bursch Muffler, I can't remember which model it's for.

1.7 or 2.0.

Does anyone here know how I can check it for GGW if someone knows where I should check once I remove the bubblewrap and "Microsoft TAPE"!

Thx,

Dave

[gollygwagen]

I have a brand new Bursch Muffler, I can't remember which model it's for.

1.7 or 2.0.

Does anyone here know how I can check it for GGW if someone knows where I should check once I remove the bubblewrap and "Microsoft TAPE"!

Thx,

Dave

From the pictures it looks like the 2.0 and 1.7 are pretty different, can you tell from looking?

Exhaust options

[poorsche914]

Different dimensions as shown in this graphic found in another thread:



(IMG:style_emoticons/default/driving.gif)

[TheCabinetmaker]

The bolt pattern on the mounting flanges are different. Similar but different. The 1.7/1.8 flanges are higher up on the muffler. What engine do you you might save some bucks by replacing Just the muffler at a shop. You might need to remove the muffler for them to do it right

[wingnut86]

EDIT:

Well, answers that question.

If you look closely, the big white sticker says "73-74 2.0L"

Not for Catalytic Re-Conversions...

So, no go on a 1.7 Bursch...

[timothy_nd28]

You have a pretty cool looking 914, so you need to get the best muffler. Buy yourself a Triad

[gollygwagen]

You have a pretty cool looking 914, so you need to get the best muffler. Buy yourself a Triad

My 914 is a heap for now, but it WILL be good looking someday.

Link to the Triad?

[timothy_nd28]

You have a pretty cool looking 914, so you need to get the best muffler. Buy yourself a Triad

My 914 is a heap for now, but it WILL be good looking someday.

Link to the Triad?

I was misguided. I assumed that green teener in your first post was yours. The triad exhuast can be found in member venders, do a search on the forum.

[rhodyguy]

engine displacement is less a factor than your heat exchangers with the exhaust options. verify whether you have 1.7/1.8, 2.0, or the 75' version hes before you purchase.

k