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06-10-2019, 09:30 AM
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#1 |
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Registered User
Join Date: Sep 2015
Location: Lake Placid florida
Posts: 599
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Droning exhaust.
My setup is ramhorns, small block Chevy motor, 2 inch pipes. The mufflers are just about under the seat and the pipes come out in front of the wheels.
I have an irritating droning, but it is only at idle. Will running the pipes out the back get rid of this? Please don't tell me I have to move the mufflers! p.s. yeah the pic has headers, but it's ramhorn now. Thanx
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1967 C-10 4-speed, 350v8 |
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06-10-2019, 10:01 AM
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#2 | |
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The Older Generation
  
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,329
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Re: Droning exhaust.
Quote:
You might try a set of "J" pipes. The guy at the muffler shop I go to had never heard of them. He couldn't believe what a difference they made in the exhaust sound after he got them installed..... Exhaust still sounds good, just no drone. Chart below the picture to calculate the length you need. It is just a pipe shaped like a "J", installed just behind the muffler. It is capped at the end and the frequency bounces back and cancels itself out. You can't just make them any length and expect them to work. That's why I recommend doing some reading on them. I think mine are 23.5 inches long. LockDoc
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Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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06-10-2019, 10:48 AM
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#3 |
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Proprietor of Dale's Corner
Join Date: Nov 2012
Location: Vacaville , CA
Posts: 15,834
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Re: Droning exhaust.
I'm running a 402 with headers and flowmasters. I had the mufflers installed as close to the rear diff as possible. The tailpipes exit behind the rear tire at about a 45* angle. It's fairly loud but no drone and quiet in the cab.
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"Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man |
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06-10-2019, 10:58 AM
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#4 |
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Registered User
Join Date: Nov 2011
Location: Idaho
Posts: 857
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Re: Droning exhaust.
Move the cans lol.
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06-10-2019, 11:19 AM
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#5 |
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Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,177
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Re: Droning exhaust.
Under the cab? That's the problem I believe. I have mine under the bed with turn downs and I don't get any drone (but I also have a sound deadened cab.
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"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
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06-10-2019, 11:22 AM
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#6 |
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Registered User
Join Date: Jul 2015
Location: 2nd left past the stump on a dirt road.
Posts: 2,629
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Re: Droning exhaust.
I had mine with the mufflers under the cab and had the same problem. Did not really notice it until I muved da mufflers to da back o de bed man!
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06-10-2019, 11:32 AM
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#7 | |
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Senior Member
Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,795
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Re: Droning exhaust.
Quote:
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I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson |
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06-10-2019, 12:12 PM
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#8 |
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Senior Member
Join Date: Jun 2009
Location: Portland - OR
Posts: 242
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Re: Droning exhaust.
What kind of mufflers? Some are worse than others
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06-10-2019, 02:05 PM
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#9 |
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Registered User
Join Date: Feb 2019
Location: Nor Cal
Posts: 822
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Re: Droning exhaust.
Under the cab is yer problem right there...
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1968 C20 Fleetside 396 4sp PS PB AC CST . https://www.youtube.com/watch?v=RWK8GgWD4uA |
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06-10-2019, 04:42 PM
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#10 |
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Registered User
Join Date: Mar 2014
Location: Simi, CA
Posts: 495
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Re: Droning exhaust.
You have a compound issue, muffler under the cab and no crossover pipe. Looks clean thought!
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Made in America by Americans |
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06-10-2019, 08:55 PM
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#11 |
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Registered User
Join Date: Jul 2015
Location: Augusta, ks
Posts: 20
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Re: Droning exhaust.
This! From LockDoc, J-Pipes. I tried this on my 66 c10 it had a drone at about 1600 rpm at 55 mph. I couldn't stand to drive the truck. I took out my h-pipe and tried them there way before the mufflers. It took away all of the drone. Someday I will put the H-Pipe back in and try them after the mufflers and see what happens.
Last edited by lilredfifty; 06-10-2019 at 09:00 PM. Reason: Mispelled words |
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06-10-2019, 09:30 PM
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#12 |
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Who Changed This?
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,088
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Re: Droning exhaust.
I ran headers with a Flowmaster system all the way out the back on my '68 Skylark (SBC powered). It had an h-pipe, as well. The mufflers were in the stock position just forward of the rear axle. The drone was horrendous, and it was my commuter car. The only thing to quiet that exhaust was better mufflers. The j-pipes are frequency-dependent, so I wouldn't use them, personally. When I do the exhaust on my truck, it's getting Cadillac mufflers (and Dyno-Mat, eventually).
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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06-10-2019, 10:35 PM
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#13 |
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Registered User
Join Date: Feb 2015
Location: TX Hill Country
Posts: 150
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Re: Droning exhaust.
LockDoc I am running a helmholtz resonator that you are describing on my 5.7 Toyota Tundra daily driver with no muffler(s) at all and they do work!
Yes move the muffler to behind/after the cab. Chambered mufflers are the worst about drone. A crossover or the smallest of glass packs on the tailpipe as a resonator will help. Exhaust exit out a side is a big plus too and you have that. |
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06-11-2019, 09:58 PM
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#14 |
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Registered User
Join Date: Sep 2015
Location: Lake Placid florida
Posts: 599
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Re: Droning exhaust.
Thanx for the input. I would like to use the chart from Locdoc and take it to the muffler guy, but my drone is at idle and the chart starts at 1400rpm. Hope I can still do it that way, it would be so much cheaper.
And I told you guys NOT to tell me to move the mufflers 
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1967 C-10 4-speed, 350v8 |
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06-11-2019, 10:30 PM
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#15 | |
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Proprietor of Dale's Corner
Join Date: Nov 2012
Location: Vacaville , CA
Posts: 15,834
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Re: Droning exhaust.
Quote:
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"Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man |
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06-11-2019, 10:43 PM
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#16 |
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Senior Member
 
Join Date: Sep 2008
Location: Harrison, Arkansas
Posts: 9,786
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Re: Droning exhaust.
My dad bought a 69 new and I had a 72 Cheyenne Super that both had the drone. I changed the obvious things on the 72 but it still had the drone when I sold it.
I did a search and couldn't find the old info I was looking for, but I remember a thread that indicated the hood hinge springs. As I remember it, They slid a piece of foam or rubber inside the hinge to stop the vibration (drone). Surely somebody remembers that thread. Sound nuts, but I'm serious.
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other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
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06-11-2019, 10:47 PM
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#17 |
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Registered User
Join Date: Feb 2015
Location: TX Hill Country
Posts: 150
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Re: Droning exhaust.
Blue thank you for being a good sport. When you look at Lock Doc's chart you will see that lower the RPM the longer the tube so take an educated guess as to length. Those tubes really do work. The science is sort of cool. Basically they are a quarter wave and bounce wave back onto the incoming wave to cancel it out. RPM, temperature and other variables are at work but with a little adjusting/tuning you will get it and be pleased I think.
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