Was out on a drive and accelerating then all of a sudden boom! Crazy loud exhaust sound starts coming from my 1.7L. Sounded to me like the muffler fell off but I’ve given it a once over and don’t see anything yet. Wanted to post this video to see f anyone has any feedback on what I might be dealing with here. Afraid this may be the 1st big problem I’m dealing with here.

Here’s a link to the video I uploaded.
https://m.youtube.com/watch?v=nXRry73OB4w&a...eature=youtu.be

Cheers!!

You have blown out a spark plug. It happens.

Or worse yet, a blown engine. Ask me how I know.

How do yo know?

Please check smog valve hole first. Happened to me once.The place where the stupid smog pump got plumbed into the head. I got lucky and just needed to plug it (there are articles here on how to do that). I hope yours isn't catastrophic. Best of luck.
Not on a '73 though. Is it the stock engine?

Yes it’s stock for the most part. Just a carb swap and that’s it

I bet you blew a plug as well. Are all the spark plugs still in ?

Had to check. Hopeful thinking.

Was the "boom" catastrophic as in she's done instastop, or did it try to sorta run before you shut it off? Is it leaking oil? Drain the oil and have a look at the particles.

Yeah it doesn’t sound catastrophic but I’m a new to the 914 world so hopefully it is just a plug. I’ll be investigating here after I finish this margarita. Was planning to replace the 1.7L with a 2.0 but not this soon ha!!!

Yeah it's pretty easy to determine if it's a plug. The plug will just be hanging there or laying there free, no longer attached to the engine. Sure sounds like it from the video.

It appeared to have some loss of power but continued to run just fine until I got to my house. It was just crazy loud. Thought the exhaust had blown out since I was accelerating but still at a very low rpm. I wasn’t pushing it that hard at all. I was just down the street and only had to drive it for 30secs before I was back at the house. No apparent major oil leak detected when I got home. Tried fifeing it back up after a few minutes and ran it for 10sec with no issues other than the fact it was loud as hell.
Cheers!!

Let's hope it's that. Thought we covered the idea, but hey... Share pics of your plugs. That will solve more than one mystery.

The sound out a ratty exhaust is completely different than the popping out of an engine's head. Dammit I can't fix you. You have learning to do. But you are in the right place for that.

Went and picked up the 914 starter kit. Couldn’t help myself. Let’s see what the heck’s going on here.

Click to view attachment

Well y’all are amazing! Here ya go. Blown plug
Click to view attachment
Now back to business and thank you everyone.

Here’s the plug. Autolite 63. So why would this happen?
Click to view attachment

50 year old aluminum heads. They don't last forever.

Will this happen often or do the heads need to be replaced?

Not all that common but it happens. Hopefully the threads are intact. Autolite plugs are not the preferred plug for a 914. That plug looks fairly new maybe it was never properly tightened. If the threads are damaged you can install a thread repair kit from Helicoil or Time Cert.

Thank you! Can you recommend a good set of plugs?

According to the Autolite website that is not the correct plug for a 914. Our cars take a .75 inch long reach plug. The cross reference calls for a #404 Autolite plug. The #63 plug is a .46 inch reach and that is probably what caused your problem. If in fact that plug is a #63 it's 1/4 of an inch too short.

My car takes 12mm plugs but I still had a box of the old 14mm plugs in the garage. I ran copper core NGK plugs. My plugs are B6ES but I think that is one heat range hotter than what is stock which I believe is a B5ES. Notice how much longer the correct length plug is?


Click to view attachment



https://www.oreillyauto.com/detail/b/copper...plug/63/2511520


https://www.oreillyauto.com/detail/b/copper...rsche/914?pos=5

I see yes thanks guys. Looks like I dodged a bullet this time. Love this little green nine fourteen!

[quote name='MiniStevieG' date='Feb 5 2019, 10:36 PM' post='2686640']
[quote name='MarkV' post='2686637' date='Feb 5 2019, 10:14 PM']
My car takes 12mm plugs but I still had a box of the old 14mm plugs in the garage. I ran copper core NGK plugs. My plugs are B6ES but I think that is one heat range hotter than what is stock which I believe is a B5ES. Notice how much longer the correct length plug is?


Click to view attachment



https://www.oreillyauto.com/detail/b/copper...plug/63/2511520


https://www.oreillyauto.com/detail/b/copper...rsche/914?pos=5
[/quote]

I see yes thanks guys. Looks like I dodged a bullet this time. Love this little green nine fourt
Installed the B6ES Plugs and wow what a difference. Runs smoother and idles better!!