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| Mufflers [message #227062] |
Fri, 25 October 2013 21:21  |
SThornbg
Messages: 127
Registered: September 2011
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So, backfired, opened the side seams of both mufflers.
Assuming there is no other damage, can the mufflers be band clamped to pull them back together and the seams welded or brazed or is that not cost effective vs. replacing the mufflers?
What is current thought on the best muffler set-up? Stay with duals up front or single in the back? Do we prefer the Flow Masters, NAPAs or ????
Thanks for any guidance.
Steve Thornburg
South Bend, IN
77 exPB 455 "Tinker Toy"
Steve Thornburg
South Bend, IN
77 exPB 455 "Tinker Toy"
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| Re: Mufflers [message #227063 is a reply to message #227062] |
Fri, 25 October 2013 21:26  |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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It is unlikely that a backfire would destroy good mufflers. Odds are your mufflers were about at the end of their useful life and the backfire just hastened things along. Don't try to patch them, it is both a waste of time and a fire hazard. Get new mufflers, and check out the entire exhaust system while you are under there.
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: Mufflers [message #227065 is a reply to message #227062] |
Fri, 25 October 2013 21:51 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Steve.
That all depends on the current condition of the muffler shells. Just about any muffler shop could do what you want if they are willing to work on the ground or if they have a 4 post hoist.
You could also go to the hardware store and get a couple of very large band (radiator hose style) clamps and wrap them around the muffler. Then start cranking them down and see how close you can get the seams to match. If they are close, take it some to muffler shop and have it welded.
Otherwise, just about any muffler shop could cut the other two off and replace them with two new ones.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Mufflers [message #227066 is a reply to message #227063] |
Fri, 25 October 2013 22:13 |
jim kanomata
Messages: 257
Registered: March 2007
Location: fremont,ca
Karma: 12
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Brand is only a small part of selecting mufflers.
We know for a fact that the volume of a muffler helps determine the noise level.
Lot of the shops will select a short ones as they are less expensive and think they are fooling a customer.
Flow masters are good, but can give a crisp sound at the outlet.
Construction of the muffler is made of heavy gauge steel so it dos not drum and make a roar in the coach.
We use the Flowmaster SS units as they are made of heavy gauge metal and flows with minimal restriction and the noise at the outlet is mellow.
If you desire a muffler at the rear, it is probably the most efficient as the pulsing of the exhausts has died down by the time it reaches the muffler and thus does not interfere the pulsing at the front.
The draw back is the selection of the configuration that you can us. We ended up copying Emery Stora's design of using a large Flow master as it comes in and out on the same side as it must nestle in the frame.
Having installed over 30-40 units in our shop, we have gained lot of experience.
Some models can not be fitted with this layout as sewer tanks are there.
We feel the best set up using the low torque headers followed with the 2.5 mufflers and Y'd into a 3 is the most efficient system to use.
All the bends should Mandrel bent as the bends do not crimp down and restrict the flow.
We can provide component parts to assist with any design.
All our joints are slip fit for a minimal leak and strength.
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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| Re: Mufflers [message #227070 is a reply to message #227066] |
Fri, 25 October 2013 22:35 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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| jim kanomata wrote on Fri, 25 October 2013 20:13 |
Brand is only a small part of selecting mufflers.
We know for a fact that the volume of a muffler helps determine the noise level.
Lot of the shops will select a short ones as they are less expensive and think they are fooling a customer.
Flow masters are good, but can give a crisp sound at the outlet.
Construction of the muffler is made of heavy gauge steel so it dos not drum and make a roar in the coach.
We use the Flowmaster SS units as they are made of heavy gauge metal and flows with minimal restriction and the noise at the outlet is mellow.
If you desire a muffler at the rear, it is probably the most efficient as the pulsing of the exhausts has died down by the time it reaches the muffler and thus does not interfere the pulsing at the front.
The draw back is the selection of the configuration that you can us. We ended up copying Emery Stora's design of using a large Flow master as it comes in and out on the same side as it must nestle in the frame.
Having installed over 30-40 units in our shop, we have gained lot of experience.
Some models can not be fitted with this layout as sewer tanks are there.
We feel the best set up using the low torque headers followed with the 2.5 mufflers and Y'd into a 3 is the most efficient system to use.
All the bends should Mandrel bent as the bends do not crimp down and restrict the flow.
We can provide component parts to assist with any design.
All our joints are slip fit for a minimal leak and strength.
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Jim,
The system I got from you had Stainless Steel "Magnaflow" mufflers, not Flowmasters. I like the sound. I have a 4" Flowmaster on my V-10 Dodge truck. It is LOUD! The fit of the GMC system was very good with nice tight joints. Thank you for providing such a good quality, easy to install product.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Mufflers [message #227097 is a reply to message #227062] |
Sat, 26 October 2013 09:53 |
SThornbg
Messages: 127
Registered: September 2011
Karma: 0
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Senior Member |
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Thanks for the comments folks. I guess the answer is two new flow masters up front.
I found Advance Auto Parts has the 52458 Flow Masters on sale till October 31 at $99.09, regularly $129.99. Guess I'd better get to the store.........
Steve T.
South Bend, IN
77 exPB 455 "Tinker Toy"
Steve Thornburg
South Bend, IN
77 exPB 455 "Tinker Toy"
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| Re: [GMCnet] Mufflers [message #227099 is a reply to message #227097] |
Sat, 26 October 2013 11:04 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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I put one spintec (sp?) up front tucked under the high point of the torsion bar xmember. It's double 2.5 inlet and single 3" outlet. Only noisy at limited load/rpm points but very quiet at cruise. The Pig has headers to 8" braided flex joints into the muffler then 3" out of muffler to 45 degree bend then straight out the back to 90 and tip. Since there is not enough clearance to " hang " the 3" pipe it has to be bracketed tight to the frame in a few places so the flex joints allow the engine to move under torque and the pipe to grow a bit with heat.
Todd Sullivan
Sully
77 royale
Seattle
> On Oct 26, 2013, at 7:53 AM, SThornbg <SThornbg@aol.com> wrote:
>
>
>
> Thanks for the comments folks. I guess the answer is two new flow masters up front.
>
> I found Advance Auto Parts has the 52458 Flow Masters on sale till October 31 at $99.09, regularly $129.99. Guess I'd better get to the store.........
>
> Steve T.
> South Bend, IN
> 77 exPB 455 "Tinker Toy"
> --
> Steve Thornburg
> South Bend, IN
> 77 exPB 455 "Tinker Toy"
> _______________________________________________
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: Mufflers [message #227103 is a reply to message #227062] |
Sat, 26 October 2013 12:06 |
mrgmc3
Messages: 210
Registered: September 2013
Location: W Washington
Karma: 2
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| SThornbg wrote on Fri, 25 October 2013 21:21 |
So, backfired, opened the side seams of both mufflers.
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A strong backfire was caused by something that should be addressed. Backfiring in the exhaust is likely due to excessive overrich mixture combusting after leaving the exhaust port. You might want to have the carb looked at, as well as a tune up. It would be shame to wreck your brand new mufflers!
Chris Geils - Twin Cities / W Wa
1978 26' Kingsley w/ very few mods; PD9040, aux trans cooler, one repaint in stock colors, R134a, Al rad, Alcoas, 54k mi
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| Re: [GMCnet] Mufflers [message #227104 is a reply to message #227097] |
Sat, 26 October 2013 12:24 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Steve,
After I installed the SECOND pair of new mufflers I decided I'd better check and see what the root cause was so I:
1) removed the dizzy cap and made sure the centrifugal advance wasn't frozen
2) removed the hose from the dizzy vacuum advance, attached a longer (clean) hose and sucked on it to make sure it worked
3) connected the following to the engine
a) dwell / tach
b) vacuum gauge
c) timing light
Checked the timing, it was a bit high so I corrected it to 12 degrees (Patterson dizzy).
Lowered the idle speed to 600 rpm with transmission in drive.
Adjusted idle mixture jets to obtain smoothest idle possible.
That was three years ago and no more backfire problems.
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of SThornbg
Sent: Saturday, October 26, 2013 9:53 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Mufflers
Thanks for the comments folks. I guess the answer is two new flow masters up front.
I found Advance Auto Parts has the 52458 Flow Masters on sale till October 31 at $99.09, regularly $129.99. Guess I'd better get to
the store.........
Steve T.
South Bend, IN
77 exPB 455 "Tinker Toy"
--
Steve Thornburg
South Bend, IN
77 exPB 455 "Tinker Toy"
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Mufflers [message #227110 is a reply to message #227062] |
Sat, 26 October 2013 14:02 |
SThornbg
Messages: 127
Registered: September 2011
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Thanks guys. The backfire occurred along with a runaway alternator that popped the top on my engine battery, fried my tach and a bunch of light bulbs. We were cruising at about 60 mph when the bang occured. We lost power and pulled to the side of the road. The engine was still running so I shut it off and went to assess the damage. We installed the toad battery and got off the interstate, but when I started the coach I knew I had a significant exhaust leak. All seems well and she runs fine. Drove another 400 miles home after the incident and another 100 since then. All I can tell is the tack is dead and the exhaust sounds a bit more "glass packy".
Distributor is a bit cruddy and there is some rust at the primary coil attach screws, so I will check it out to make sure the weights are free, etc.
Steve T.
Steve Thornburg
South Bend, IN
77 exPB 455 "Tinker Toy"
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| Re: Mufflers [message #227111 is a reply to message #227062] |
Sat, 26 October 2013 14:04 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Not certain yet but I suspect I've blown some baffles in one of my new mufflers. When we came in from Branson, I remembered I had disconnected one of my throttle return springs while troubleshooting the carb. As a result it would not return to idle instantaneously as it normally did. We pulled into the driveway after a long day and I shut the ignition off before the motor had spun down and BANG!. Sounded like my 12 gauge.
As we drove to Gadsden last weekend, we noticed a noise and determined it was exhaust. I was prepared to tighten things up at the campground but couldn't find the leak.
Back at home I still can't. I can hear it louder and with my stethoscope I can tell it's in/from the right muffler but don't feel any air puffing.
My neighbor is coming over and help me pull the pod off the roof and I'm going to get him to restrict the exhaust pipe to help me find the leak. If there is no external leak it's possible I blew a couple baffles out internally.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: [GMCnet] Mufflers [message #227114 is a reply to message #227104] |
Sat, 26 October 2013 14:31 |
jim kanomata
Messages: 257
Registered: March 2007
Location: fremont,ca
Karma: 12
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Senior Member |
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The fact the the Magnaflo and Flow masters are heavy gauge and welded, I have yet to see on blowup.
If anyone need part# for the ones we use,Email me or call.
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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| Re: Mufflers [message #227123 is a reply to message #227063] |
Sat, 26 October 2013 16:13 |
rjw
Messages: 697
Registered: September 2005
Karma: 4
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| Otterwan wrote on Fri, 25 October 2013 22:26 |
It is unlikely that a backfire would destroy good mufflers. Odds are your mufflers were about at the end of their useful life and the backfire just hastened things along.
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I don't know if that is entirely true. While testing to see what would happen if I lost engine power for my brakes, I turned off the ignition while driving. Applied the brakes several times, noted the lack of boost and poor braking, I then turned on the ignition. the resulting explosion blew out the ends of both of my brand new mufflers. Sadly they were not covered by the muffler shop warranty. I know now better then to repeat that experiment.
Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com
Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.
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| Re: Mufflers [message #227130 is a reply to message #227111] |
Sat, 26 October 2013 17:00 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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| Kerry Pinkerton wrote on Sat, 26 October 2013 12:04 |
... I'm going to get him to restrict the exhaust pipe to help me find the leak. If there is no external leak ...
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"Pressurize" the exhaust system with nice cool shop air. (ie: Take a hose from your shop compressor and slip it in the end of the exhaust pipe and seal with a shop rag.)
Easier to feel around the pipes for leaks when they are not hot.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] Mufflers [message #227135 is a reply to message #227123] |
Sat, 26 October 2013 17:50 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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52458 will be very noisy.
I looked it up.
Like I mentioned, short or smaller muffler is going to be too noidy.
Go with the 70 series, they are for motorhome.
Also the off sets on the one your going to purchas might not work too well.
On Sat, Oct 26, 2013 at 4:13 PM, RJW <mygmc@palmbeachgmc.com> wrote:
>
>
> Otterwan wrote on Fri, 25 October 2013 22:26
> > It is unlikely that a backfire would destroy good mufflers. Odds are
> your mufflers were about at the end of their useful life and the backfire
> just hastened things along.
>
>
> I don't know if that is entirely true. While testing to see what would
> happen if I lost engine power for my brakes, I turned off the ignition
> while driving. Applied the brakes several times, noted the lack of boost
> and poor braking, I then turned on the ignition. the resulting explosion
> blew out the ends of both of my brand new mufflers. Sadly they were not
> covered by the muffler shop warranty. I know now better then to repeat
> that experiment.
> --
> Richard
> 76 Palm Beach
> SE Michigan
> www.PalmBeachGMC.com
>
> _______________________________________________
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> Unsubscribe or Change List Options:
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Mufflers [message #227187 is a reply to message #227062] |
Sun, 27 October 2013 09:32 |
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SeanKidd
Messages: 747
Registered: June 2012
Location: Northern Neck Virginia
Karma: 4
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Senior Member |
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http://www.gmcmhphotos.com/photos/oddsnends/p51346-oops.html
BTDT....brand new walker mufflers, I was installing my HEI, had the wrong 12v source, no 12v while cranking, but with key on....boom, of course in my frustration I was rotating the dist right and left as far as the wires would let them. Neighbors from all around wandered from their homes to see what had happened. Hehe.
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.
Colonial Travelers
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