![]() |
Register or Log In To remove these advertisements. |
|
|
![]() |
|
Thread Tools | Display Modes |
|
![]() |
#1 |
Registered User
Join Date: Sep 2017
Location: Center Point, Iowa
Posts: 82
|
Exhaust Drone Question
72 C10. 350. New exhaust. Nice, straight exhaust pipes. Mufflers back as far as they can go. Tail pipes exit behind rear weels. Drone. Changed out mufflers to stock design. Much quieter, but at speeds above 60, it still drones. Question is - isn't a drone constant? This is now a rapid pulsation. It's almost worse than if it was constant. Thought it might be a wheel out of balance, but it goes away when I let it coast at speed. Any ideas?
|
![]() |
![]() |
![]() |
#2 | |
Senior Member
![]() Join Date: Dec 2014
Location: Edmonton Alberta
Posts: 1,330
|
Re: Exhaust Drone Question
Quote:
__________________
DAVE Edmonton, Alberta 1959 Apache 1967 K20 1968 C20 1970 C10 1972 GMC 2500 1981 C10 |
|
![]() |
![]() |
![]() |
#3 |
Senior Member
![]() Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,901
|
Re: Exhaust Drone Question
Are you running headers or stock manifolds?
__________________
I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson |
![]() |
![]() |
![]() |
#4 |
Registered User
Join Date: Sep 2017
Location: Center Point, Iowa
Posts: 82
|
Re: Exhaust Drone Question
WOT is not an issue. Stock manifolds.
|
![]() |
![]() |
![]() |
#5 |
Senior Member
![]() Join Date: Jan 2009
Location: Logansport,In
Posts: 546
|
Re: Exhaust Drone Question
Do you have an H or an X pipe? If not, I wonder if this would help. Just a thought.
|
![]() |
![]() |
![]() |
#6 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,373
|
Re: Exhaust Drone Question
Yes an h- or x-pipe can settle out some of the noise. I prefer an h-pipe, but a lot of Buick guys swear by x-pipes. The connection reduces some of the pressure from the pulses as they are scavenged back and forth. The other reason is that it effectively doubles the frequency of the exhaust note, and the higher frequencies aren't as annoying as they have less energy.
__________________
~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
![]() |
![]() |
![]() |
#7 |
Moderator
![]() Join Date: Dec 2012
Location: ON, Canada
Posts: 2,157
|
Re: Exhaust Drone Question
Ensure no rubbing. Add crossover. Add resonators out back.
|
![]() |
![]() |
![]() |
#8 |
The Older Generation
![]() ![]() ![]() Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,477
|
Re: Exhaust Drone Question
-
"J" pipe cured my drone around 60mph. Picture of a "J" pipe and length calculator. Install as close to the back of the muffler as possible. End is capped off Mine are 27" long. LockDoc
__________________
Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
![]() |
![]() |
![]() |
#9 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,373
|
Re: Exhaust Drone Question
Worse comes to worst, put a pair of Cadillac mufflers on it. Those will give no rumble whatsoever. Ever heard a loud, stock Caddy? A couple to fit a 500 Cu In engine would be sure to give you enough flow! When I go to do mine, that's the route I'm taking.
__________________
~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
![]() |
![]() |
![]() |
#10 | |
Senior Member
![]() Join Date: Nov 2018
Location: Waterford California
Posts: 2,511
|
Re: Exhaust Drone Question
Quote:
After getting a ticket for loud exhaust he installed Caddy mufflers. It really took the loud out at the rear exit but it made this unique sound while idling. My best description is it sounded like you were tapping on a empty gallon paint can with a spoon all the way down the exhaust system and seemed like you could almost hear each cylinder fire individually. Never heard anything like it since... but those caddy mufflers worked. |
|
![]() |
![]() |
![]() |
#11 | |
Registered User
Join Date: Oct 2014
Location: Brandon, Manitoba, Canada
Posts: 970
|
Re: Exhaust Drone Question
Quote:
I've got a lot of drone with my shorties and Magnaflow 3 chambers. Truck is going in this week for tailpipes (now just turn downs) and I hope that will reduce or eliminate my drone which is deafening at 18-2000. I keep it in a lower gear and higher revs when I can to avoid it. EDIT: Got my tail pipes installed and it cured the drone. Much nicer to drive around. Rumbles at low throttle but still loud when tromped on. Last edited by bigmoe; 10-01-2020 at 11:32 AM. |
|
![]() |
![]() |
![]() |
#12 | |
The Older Generation
![]() ![]() ![]() Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,477
|
Re: Exhaust Drone Question
Quote:
I measured mine at the longest point after bending and cutting to fit the existing tail pipe. LockDoc
__________________
Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
|
![]() |
![]() |
![]() |
#13 |
laying low
![]() Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,200
|
Re: Exhaust Drone Question
Somewhere there is a formula for determining the length and placement of a j pipe.
__________________
Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
![]() |
![]() |
![]() |
#14 |
Registered User
Join Date: Sep 2017
Location: Center Point, Iowa
Posts: 82
|
Re: Exhaust Drone Question
Thanks for all the replies. Still curious, though. Is a drone constant? Mine pulsates. Wondering if it really is exhaust related, although don't know what else it would be.
|
![]() |
![]() |
![]() |
#15 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,518
|
Re: Exhaust Drone Question
With the cast manifolds I'd personally go with a single 3'' pipe instead of the duals
|
![]() |
![]() |
![]() |
#16 | |
The Older Generation
![]() ![]() ![]() Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,477
|
Re: Exhaust Drone Question
Quote:
LockDoc
__________________
Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
|
![]() |
![]() |
![]() |
#17 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
|
Re: Exhaust Drone Question
Sounds are hard to describe. But I consider a drone to be a constant hum to a very rapid pulsation creating a hum. I define drone as a constant harmonic and pulsation as constant rapid sounds. I run headers, never ran a crossover, and I don't feel I have had a drone in any of my vehicles I've had. Just the sound made coming out the pipes. The only time I've had a drone is with exhaust not exiting out from under the body
__________________
"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
![]() |
![]() |
![]() |
#18 |
Registered User
Join Date: Jun 2015
Location: Carlos MN
Posts: 2,038
|
Re: Exhaust Drone Question
No muffler expert by a long shot. I'm running headers, 3" collectors reduced down to 2.5", then non-xpiped to the bumper. Running Dyno Max super turbo mufflers. Zero drone.
But when I did the cab insulation I put down a layer of dynamat like insulation then the double foil sided jute insulation. Then the carpet. Did the insulation from the firewall to the back of the cab to where the gas tank would of been. Again zero drone. One more thing. When I was much younger I worked for a Chev dealership and we were the first with a exhaust pipe bender and the training we had from the supplier was that the first exhaust hanger after the manifold was at the muffler. It gives some flex to the exhaust system. |
![]() |
![]() |
![]() |
#19 |
70+ ( Old Skool Club )
![]() Join Date: Nov 2003
Location: Saskatoon, Saskatchewan ,Canada
Posts: 9,115
|
Re: Exhaust Drone Question
I have DynoMax SuperTurbos on mine and an H pipe and no drone. I'd post a video of it idling if I could on here.
__________________
1972 C10 Custom/Deluxe 613 Highlander 406/700R4 1999 White Tahoe LS 4x2 with Z56 Police Package 1992 K1500 GMC Suburban Members I have personally met: MusicMan70 - HeavyD - ChewyChevy67 - StingRay -71SWB4x4 - 67 Burb - DeadheadNM - too much stuff - bc65 - das601 " Circumsatances Do Not Change Responsibility " " The Sky is not the Limit, Your Mind is." Marilyn Monroe .. RIP Charlie Watts 1941 - 2021 |
![]() |
![]() |
![]() |
#20 |
Senior Member
![]() ![]() Join Date: Sep 2008
Location: Harrison, Arkansas
Posts: 9,815
|
Re: Exhaust Drone Question
My dad bought a new 69 that had the drone and I had a 72 Cheyenne Super that had it. I changed exhaust and hangers, motor mounts, transmission mount, and tried any thing else I could think of. I never did find it.
__________________
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. |
![]() |
![]() |
![]() |
#21 | |
Post Whore
![]() Join Date: Feb 2016
Location: Portland Oregon
Posts: 11,086
|
Re: Exhaust Drone Question
Quote:
I will say that straight pipes are noisy in their own way which is why you never see them installed from the factory. Straight pipes would be cheaper to build, but manufacturers are willing to spend money for bent pipes. Obviously packaging is a concern in all newer vehicles but when was the last time you saw factory straight pipe? I have found that tires are usually the culprit when a pulsing noise is heard. Can you swap them? It would be good to confirm one way or the other before spending money on exhaust items.
__________________
Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. ![]() RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377 |
|
![]() |
![]() |
![]() |
#22 |
Registered User
Join Date: Feb 2015
Location: TX Hill Country
Posts: 150
|
Re: Exhaust Drone Question
I have what Lock Doc describes on my daily driver without a muffler and it works perfectly. Drone is not a constant and that Helmholtz tube has to be tuned to length work for the frequency the drone occurs worst at.
Another trick is to put in a short glass pack muffler as a resonator. With that and the X/Y pipes is you are breaking up the long runs of uninterupted pipe. |
![]() |
![]() |
![]() |
#23 |
Senior Member
![]() Join Date: Nov 2018
Location: Waterford California
Posts: 2,511
|
Re: Exhaust Drone Question
X or H pipe will cure 80% if not all of it
|
![]() |
![]() |
![]() |
#24 |
Registered User
![]() Join Date: Mar 2005
Location: Jurupa Valley, Ca
Posts: 1,210
|
Re: Exhaust Drone Question
I have a 2 1/2" dual system stock ram manifolds, H pipe, dynomax mufflers and exits rear under bumper. No drone and sounds great a low speeds especially with the windows down. At highway speeds with windows up and A/C running I hear more tire and wind noise than exhaust.
__________________
Terry 1970 Custom Camper/C20 , GM Crate 350/7004R, Dana 60, factory AC |
![]() |
![]() |
![]() |
#25 |
Registered User
Join Date: Sep 2017
Location: Center Point, Iowa
Posts: 82
|
Re: Exhaust Drone Question
Great replies. I appreciate all of them. If I can borrow a couple from a friend, I'll try swapping tires first and see if that works. Then go from there. Lots of variables to consider.
|
![]() |
![]() |
![]() |
Bookmarks |
|
|