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Old 06-10-2019, 09:30 AM   #1
dave`12
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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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Old 06-10-2019, 10:01 AM   #2
LockDoc
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Re: Droning exhaust.

Quote:
Originally Posted by dave`12 View Post
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

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.

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Old 06-10-2019, 10:48 AM   #3
Ol Blue K20
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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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Old 06-10-2019, 10:58 AM   #4
Daaaanz67
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Re: Droning exhaust.

Move the cans lol.
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Old 06-10-2019, 11:19 AM   #5
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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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Old 06-10-2019, 11:22 AM   #6
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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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Old 06-10-2019, 11:32 AM   #7
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Re: Droning exhaust.

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Originally Posted by dave`12 View Post
Please don't tell me I have to move the mufflers!
OK, I'm not going to tell you, but... the further back the mufflers are, the less drone you'll have in the cab.
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Old 06-10-2019, 12:12 PM   #8
Mbeef61
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Re: Droning exhaust.

What kind of mufflers? Some are worse than others
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Old 06-10-2019, 02:05 PM   #9
Astro-Balls
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Re: Droning exhaust.

Under the cab is yer problem right there...
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Old 06-10-2019, 04:42 PM   #10
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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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Old 06-10-2019, 08:55 PM   #11
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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.

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Old 06-10-2019, 09:30 PM   #12
Steeveedee
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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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Old 06-10-2019, 10:35 PM   #13
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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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Old 06-11-2019, 09:58 PM   #14
dave`12
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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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Old 06-11-2019, 10:30 PM   #15
Ol Blue K20
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Re: Droning exhaust.

Quote:
Originally Posted by dave`12 View Post
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
Sorry but I couldn't lie to you......
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Old 06-11-2019, 10:43 PM   #16
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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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Old 06-11-2019, 10:47 PM   #17
6T7 C10
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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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