Original mufflers question for HP engines

[Mariposa Mike]

I recently purchased a 66 Charger with the 383HP engine. The muffler system appears fairly new and correct with the cross over pipe between the exhaust pipes. They have a good sound at idle and on acceleration but they have a loud drone sound at highway speeds. I had a new 63 Plymouth 383 and a new 67 Plymouth 440HP in the 60's and they did not have the drone. So I'm asking what would be a good sounding stock muffler for these cars. I cannot live with the drone but need to know what to tell a muffler shop about replacement. Any info would be appreciated.

 

[Don Frelier]

An H-pipe is not an original equipment setup for a 66 383. (But it's a good setup)
Get a set of reproduction hemi mufflers, accurate or Dale's Cuda shop are some good sources.
Couldn't find them on Dale's Cuda shop (they used to have them at a good price)

I have them on my 66 383 with a homemade h-pipe and it's excellent.

 

[68BabyBlue]

I'm also a fan of the reproduction hemi mufflers. Ran the originals on my first three GTXs. When Baby Blue came back with flow masters in 2013, the drone at highway speeds drove me crazy. I was too cheap to rip out a new exhaust system, so I lived with it. Current owner loves them. To each his own. I have the reproduction hemi mufflers in the current GTX with a factory style H-pipe, and that's still my system of choice.

 

[gtx6970]

My Dynomax turbos sound good.
And I have zero drone

 

[TorRed]

I believe Accurate exhaust has videos of both their Hemi and performance mufflers, both sound good to me. I'm going with 2.5" Dynomax Ultraflos after a ton of research including videos and recommendations.

 

[sam dupont]

when in doubt, copy the factory

edit: I believe your GTX would have had Hemi Mufflers

 

[Mariposa Mike]

Factory is what I was thinking as well but I don't know if those are still available and what they are called. If the hemi muffler works without the drone then I can try to source them. Or the Dyno max. I'll try to find a number for them. I will also search for the Accurate video. All good advice and a lot of research has been done already. That is what I was looking for and hoping to get.

 

[Don Frelier]

Accurate has both original and hemi style.
You should check your pipe sizes before you order anything.

 

[Mariposa Mike]

Just came in from doing that. 2 1/2 inch by 20 inch with the pipe offset to the driveline side. The 20 inch might be the clue to the noise as the Accurate site looks to be 26 inch for a mellower? noise.

 

[Don Frelier]

Hemi muffler next to a Magnaflow 3 chamber stainless.
Got sick of the magnaflows (but they sounded great if you were outside the car)

 

[Mariposa Mike]

Just spoke to an office lady at Accurate and her records show/confirms that my car did not come with an H pipe. Also the measurement I gave is not correct because you have to include the inlet/outlet. So I have 26 inch mufflers. She recommends I talk to the tech they have since I have a modified exhaust from 2 1/4 to 2 1/2. I still need to check the pipe size from the manifolds to the muffler but it "looks" to be the same all the way back. The stock muffler they have is 2 1/4 both ends and number ACC 6885. They can modify it to 2 1/2. The 6885 did not have a video to hear but the ACM 55 sounded nice and is 2 1/4 x 2 1/2. Their tech is not available until next week so I have to wait for a call to discuss this further.

 

[Mariposa Mike]

And one more update. Crawled under further up and the exhaust is 2 1/4 off the manifolds (stock) and then increased with a section of pipe to 2 1/2 before the muffler. Right in the area of the H pipe. So the mufflers on there now are 2 1/2 on both ends. That might mean the new muffler needs to have an adapter welded on unless a hemi muffler would work...but might be too noisy. I'll update this after I speak with the tech next week. Should probably get a picture(s) of what is on there too to help the tech. The pipes are three pieces plus the muffler from end to end. Appear to not be welded which should help somewhat.

 

[Don Frelier]

FYI - Originals weren't 2 - 1/4", they were 2".

 

[Mariposa Mike]

That magnaflo inlet looks pretty small. I'm kinda surprised stock for a 383HP would be 2". It's gotta breathe but twice pipes help a lot. Imagine the assembly line with all the different engines coming down the line. Today it's more automated but maybe back then they had someone supplying the the parts for multiple orders of the same cars and then switching out as the orders changed. Yikes! Worker...damn..what pipes go on this one.

 

[496 polara]

Or put a pair of glasspacks before the mufflers.I would be surprised if the drone isn't gone.

 

[gtxrt]

I like the walker quiet flow. they flow a litttle better than a stock muffler and have just a slight sound. no drone. they are between the walker fx sound and the walker big dynomax.

 

[AR67GTX]

Or put a pair of glasspacks before the mufflers.I would be surprised if the drone isn't gone.

I heard a car start up at our cruise-in this afternoon with a set of glass packs. The sound bought back memories from 50 years ago they sounded so good. I’m tempted to get a set and put on my car.

 

[Virg464]

I'm running a set of Purple Hornies on my 66 coronet, I can't hear any drone...

 

[33 IMP]

I'm running a pair of purple hornies. I can't hear.......

 

[Don Frelier]

I'm running a set of Purple Hornies on my 66 coronet, I can't hear any drone...

Have you ever driven it for a couple hours straight?