Home » Public Forums » GMCnet » Consensus on single or dual mufflers ??
| Consensus on single or dual mufflers ?? [message #231986] |
Mon, 02 December 2013 15:41  |
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SteveW
Messages: 538
Registered: June 2005
Location: Southern California - Ora...
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Greetings !!
I can hear the beginnings of an exhaust leak - pretty sure it's around the muffler(s).
1973 23 footer, dual mufflers, heat shield on flooring...
I recall a thread or two commenting on a preference for a single muffler rather than two.
Seeing as I might be in an exhaust system repair mode soon - what say y'all ??
As always, THANK YOU for the treasures of information that are available here.
Steve W
Southern California
Steve W
1973 : 23'
Southern California
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| Re: Consensus on single or dual mufflers ?? [message #231987 is a reply to message #231986] |
Mon, 02 December 2013 15:56  |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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Might not be the best example, but my 1992 1-ton Chevy with a 454 has the large single muffler, and is by far the quietest truck I have ever owned. However, it does not have that classic big block sound that dual mufflers give.
My Royale has dual mufflers and sounds like a classic muscle car, which I sort of like. I think either system is fine, just whatever you prefer.
Last, if your exhaust system is in good shape other than the mufflers, replacing just the mufflers should be cheaper than an entire new exhaust system.
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Consensus on single or dual mufflers ?? [message #231990 is a reply to message #231986] |
Mon, 02 December 2013 16:17 |
John Hunt
Messages: 70
Registered: January 2011
Location: Orange County, CA
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Hi Steve,
I assume you're talking about single muff rear mount Vs. dual muff front? I am trying to decide now which to go with, and will look forward to responses on both configs.
At first I thought single rear would be the way to go - quieter inside and move a heat source away from the engine compartment, but I recall others responding in the past that GMC engineers could have done this but opted for dual muffs near engine, and moving muffler to rear changes engine performance that might require timing and/or mixture tweak.
So it's paralysis by analysis for me - currently planning to go SS system from Jim K with front dual muffs but a little hesitant to pull the trigger.
John
'76 Eleganza
Orange County CA
1976 Eleganza II,
1969 Lotus Elan Plus 2,
1978 Merlyn Formula Ford,
1981 Lola Sports 2000
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| Re: Consensus on single or dual mufflers ?? [message #231992 is a reply to message #231990] |
Mon, 02 December 2013 16:37 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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The dual front mufflers was popular back in the 60's, or at least more common.
The single rear muffler is a better design for many reasons.
Yes, you should reject your carb, but you should probably re-jet it anyway...
BTW
Royales has a second rear tank which makes the rear muffler very difficult...
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: Consensus on single or dual mufflers ?? [message #232001 is a reply to message #231986] |
Mon, 02 December 2013 17:06 |
cbryan
Messages: 451
Registered: May 2012
Location: Ennis, Texas
Karma: 3
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Hi,
I read this with interest. You might note that Emery Stora has his dual in-tank fuel pumps,and that he has no problem with vapor lock.
Thinking about things for just a minute, you might recall that Emery also has a rear muffler setup. How much extra heat does that hot exhaust going into two mufflers dissipate into the air going back just in a few feet to the fuel tanks in unmodified coaches?
Could it be better to, if convenient, go to a rear muffler setup to minimize heat gain to the gas tanks? I do think so, but have the Royale rear gray tank problem. I don't know the solution for sure, but I think it best to get that heat back behind the tanks as quickly as possible. I think it probable that it could be possible to mount a muffler sideways at the very back of the Royale, inlet and outlet at the same end.
Has Emery solved his vapor lock problem because of his in-tank fuel pump setup or has he solved it because he has moved two very big heat dissipators behind the tanks?
If it were me, I would investigate losing some weight by going to the rear muffler, along with helping avoid vapor lock problems. Some do say that there is an exhaust "bark" with rear single mufflers. It wouldn't bother Dan Gregg. Someone has already installed a resonator to damp the bark.
Johnny Bridges rather likes the bark.
Carey Bryan
Carey from Ennis, Texas
78 Royale, 500 Cadillac, Rance Baxter EFI.
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| Re: [GMCnet] Consensus on single or dual mufflers ?? [message #232004 is a reply to message #232001] |
Mon, 02 December 2013 17:42 |
Emery Stora
Messages: 959
Registered: January 2011
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I think I can easily answer that. I have had the rear muffler for several years before I put the pumps into the tanks. I still had vapor lock
As soon as I put the pumps into the tanks vapor lock stopped.
So I can say with certainty the it was not the muffler placement.
Emery Stora
On Dec 2, 2013, at 4:06 PM, Carey Bryan <chbryan@bigfoot.com> wrote:
>
>
> Hi,
>
> I read this with interest. You might note that Emery Stora has his dual in-tank fuel pumps,and that he has no problem with vapor lock.
>
> Thinking about things for just a minute, you might recall that Emery also has a rear muffler setup. How much extra heat does that hot exhaust going into two mufflers dissipate into the air going back just in a few feet to the fuel tanks in unmodified coaches?
>
> Could it be better to, if convenient, go to a rear muffler setup to minimize heat gain to the gas tanks? I do think so, but have the Royale rear gray tank problem. I don't know the solution for sure, but I think it best to get that heat back behind the tanks as quickly as possible. I think it probable that it could be possible to mount a muffler sideways at the very back of the Royale, inlet and outlet at the same end.
>
> Has Emery solved his vapor lock problem because of his in-tank fuel pump setup or has he solved it because he has moved two very big heat dissipators behind the tanks?
>
> If it were me, I would investigate losing some weight by going to the rear muffler, along with helping avoid vapor lock problems. Some do say that there is an exhaust "bark" with rear single mufflers. It wouldn't bother Dan Gregg. Someone has already installed a resonator to damp the bark.
>
> Johnny Bridges rather likes the bark.
>
> Carey Bryan
> --
> Carey from Ennis, Texas
> 78 Royale, 500 Cadillac, Rance Baxter EFI.
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| Re: Consensus on single or dual mufflers ?? [message #232008 is a reply to message #231986] |
Mon, 02 December 2013 17:57 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Emery Stora was the one who designed / first installed the single rear muffler system on a GMC. If Emery makes a recommendation I would definitely consider it.
I had one of my two mufflers burn a hole in the top of it and Walker would not warranty it. So I looked at Emery's design. Since I already had a 3" exhaust, it was a simple job to put in two bypass pipes in front to replace the mufflers and cut out a section of the rear to mount the rear Flowmaster muffler.
If I hadn't already had good pipes, I would have ordered the single rear muffler system from Jim K. I watched his guys install a complete single system on someone's coach in his shop one time. It was an easy upgrade. Jim's system requires no welding and is held together with supplied band clamps.
One advantage of the single system is you do have the possibility of a muffler clogging up and forcing exhaust gas through the intake crossover underneath the carb. This happens more often than you would thing. Ask Jim K. about it.
I vote for the single rear muffler system designed by Emery / manufactured and sold Jim K.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Consensus on single or dual mufflers ?? [message #232013 is a reply to message #231986] |
Mon, 02 December 2013 18:06 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Steve,
In all the enthusiasm for the single rear muffler, don't forget that your
23' GMC has less room in the rear than does a 26'. The commonly used
muffler won't fit the 23'. However, you CAN install a smaller one:
http://www.gmcmhphotos.com/photos/g4453-23-rear-muffler.html
That said, I have not yet gotten up the nerve to try running with only that
RESONATOR and no forward mufflers. :-)
Ken H.
On Mon, Dec 2, 2013 at 4:41 PM, Steve Weinstock <steve.weinstock@cox.net>wrote:
>
>
> Greetings !!
>
> I can hear the beginnings of an exhaust leak - pretty sure it's around the
> muffler(s).
>
> 1973 23 footer, dual mufflers, heat shield on flooring...
>
> I recall a thread or two commenting on a preference for a single muffler
> rather than two.
>
> Seeing as I might be in an exhaust system repair mode soon - what say
> y'all ??
>
> As always, THANK YOU for the treasures of information that are available
> here.
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: Consensus on single or dual mufflers ?? [message #232015 is a reply to message #232008] |
Mon, 02 December 2013 18:27 |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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| Ken Burton wrote on Mon, 02 December 2013 15:57 |
One advantage of the single system is you do have the possibility of a muffler clogging up and forcing exhaust gas through the intake crossover underneath the carb. This happens more often than you would thing. Ask Jim K. about it.
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This could be avoided by installing a tube between the headpipes. This was common on old muscle cars. I think it was called a balance tube or equalizer. The intent was to equalize backpressure between dual exhaust. I'm not sure how practical this would be on a GMC, but it's a thought.
Here's a link to one type:
http://www.jegs.com/p/Hedman/Hedman-X-Treme-Exhaust-Equalizers/747903/10002/-1
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Consensus on single or dual mufflers ?? [message #232022 is a reply to message #231986] |
Mon, 02 December 2013 19:31 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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| SteveW wrote on Mon, 02 December 2013 15:41 |
Greetings !!
I can hear the beginnings of an exhaust leak - pretty sure it's around the muffler(s).
1973 23 footer, dual mufflers, heat shield on flooring...
I recall a thread or two commenting on a preference for a single muffler rather than two.
Seeing as I might be in an exhaust system repair mode soon - what say y'all ??
As always, THANK YOU for the treasures of information that are available here.
Steve W
Southern California
|
Steve,
Has anyone installed a single rear muffler system on a 23 ft coach?
The only rear muffler install I know of is KenH's -- but at the time it was in addition to front mufflers.
And on our 73 coaches with the wood floor -- the triangular area just above the pipe in this picture by KenH, has dried out considerably and in-fact on mine was charred because of a rusted out tail pipe.
http://www.gmcmhphotos.com/photos/23-rear-muffler/p19300.html
I am staying with front mufflers on my 73, 23, and I will be adding more heat shielding to them.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
[Updated on: Mon, 02 December 2013 19:42] Report message to a moderator |
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| Re: [GMCnet] Consensus on single or dual mufflers ?? [message #232030 is a reply to message #232001] |
Mon, 02 December 2013 20:28 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Next time I haule the new used toad to Tejas - likely this summer to SA, I'll buy ya a beer and let you hear the toad bark. It'll take you back to a flathead with Offenhauser heeads and two Strombergs and straight pipes. Toad's a Ranger 302 with 30" headers, 3 inch collectors and Smittys, and then 2 1/2" pipes out the back. There ain't a baffle anywhere in it. It is a safety measure, if you get it above idle in anybody's campground, they'll throw you out for disturbing people.
--johnny
'76 23' transmode norris
Brase;ton, GA
________________________________
From: Carey Bryan <chbryan@bigfoot.com>
To: gmclist@temp.gmcnet.org
Sent: Monday, December 2, 2013 6:06 PM
Subject: Re: [GMCnet] Consensus on single or dual mufflers ??
Hi,
I read this with interest. You might note that Emery Stora has his dual in-tank fuel pumps,and that he has no problem with vapor lock.
Thinking about things for just a minute, you might recall that Emery also has a rear muffler setup. How much extra heat does that hot exhaust going into two mufflers dissipate into the air going back just in a few feet to the fuel tanks in unmodified coaches?
Could it be better to, if convenient, go to a rear muffler setup to minimize heat gain to the gas tanks? I do think so, but have the Royale rear gray tank problem. I don't know the solution for sure, but I think it best to get that heat back behind the tanks as quickly as possible. I think it probable that it could be possible to mount a muffler sideways at the very back of the Royale, inlet and outlet at the same end.
Has Emery solved his vapor lock problem because of his in-tank fuel pump setup or has he solved it because he has moved two very big heat dissipators behind the tanks?
If it were me, I would investigate losing some weight by going to the rear muffler, along with helping avoid vapor lock problems. Some do say that there is an exhaust "bark" with rear single mufflers. It wouldn't bother Dan Gregg. Someone has already installed a resonator to damp the bark.
Johnny Bridges rather likes the bark.
Carey Bryan
--
Carey from Ennis, Texas
78 Royale, 500 Cadillac, Rance Baxter EFI.
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Consensus on single or dual mufflers ?? [message #232038 is a reply to message #232030] |
Mon, 02 December 2013 21:00 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Did you also have the pennies in the block heat riser tubes, Johnny? Talk about making a motor bark!
Didn't want to run worth a damn without considerable warmup time in an upstate New York winter, though!
Mac in OKC
Money Pit
> Date: Mon, 2 Dec 2013 18:28:46 -0800
> From: jhbridges@ymail.com
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] Consensus on single or dual mufflers ??
>
> Next time I haule the new used toad to Tejas - likely this summer to SA, I'll buy ya a beer and let you hear the toad bark. It'll take you back to a flathead with Offenhauser heeads and two Strombergs and straight pipes. Toad's a Ranger 302 with 30" headers, 3 inch collectors and Smittys, and then 2 1/2" pipes out the back. There ain't a baffle anywhere in it. It is a safety measure, if you get it above idle in anybody's campground, they'll throw you out for disturbing people.
>
> --johnny
> '76 23' transmode norris
> Brase;ton, GA
>
>
> ________________________________
> From: Carey Bryan <chbryan@bigfoot.com>
> To: gmclist@temp.gmcnet.org
> Sent: Monday, December 2, 2013 6:06 PM
> Subject: Re: [GMCnet] Consensus on single or dual mufflers ??
>
> Hi,
>
> I read this with interest. You might note that Emery Stora has his dual in-tank fuel pumps,and that he has no problem with vapor lock.
>
> Thinking about things for just a minute, you might recall that Emery also has a rear muffler setup. How much extra heat does that hot exhaust going into two mufflers dissipate into the air going back just in a few feet to the fuel tanks in unmodified coaches?
>
> Could it be better to, if convenient, go to a rear muffler setup to minimize heat gain to the gas tanks? I do think so, but have the Royale rear gray tank problem. I don't know the solution for sure, but I think it best to get that heat back behind the tanks as quickly as possible. I think it probable that it could be possible to mount a muffler sideways at the very back of the Royale, inlet and outlet at the same end.
>
> Has Emery solved his vapor lock problem because of his in-tank fuel pump setup or has he solved it because he has moved two very big heat dissipators behind the tanks?
>
> If it were me, I would investigate losing some weight by going to the rear muffler, along with helping avoid vapor lock problems. Some do say that there is an exhaust "bark" with rear single mufflers. It wouldn't bother Dan Gregg. Someone has already installed a resonator to damp the bark.
>
> Johnny Bridges rather likes the bark.
>
> Carey Bryan
> --
> Carey from Ennis, Texas
> 78 Royale, 500 Cadillac, Rance Baxter EFI.
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| Re: Consensus on single or dual mufflers ?? [message #232042 is a reply to message #231986] |
Mon, 02 December 2013 21:15 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Steve,
KISS it. Single front muffler. Cheaper, out of the box, NO HASSLE install, and works just fine.
No significant improvement by doing anything else- unless you prefer to spend extra money and labor rather than driving and enjoying the coach. JMHO.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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