1966 C10 Exhaust Resnonance issues

[njc1230]

Hi guys, hoping ya'll mind might have some answers to this conundrum. My 1966 C10(short wheelbase) has a 350 Chevy(w/headers) and 700r4 swap and I just took it out for a test drive after finishing a 2.25" exhaust system. Above 1800 rpm, or so, the exhaust is tolerable, but when it drops below 1800 rpm it develops an unbearable resonance. Could barely talk to my dad in the seat next too me, and it quite literally started to give the both of us a headache. I'm using 2 chamber mufflers included with a Speedway Motors kit I ordered a few months ago and I'm less than confident that the mufflers are quality. When I got the truck it had this horrendous 2" exhaust system with glass packs that made it loud, but had no resonance. However, I've seen people put in more restrictive mufflers and have no resonance issues either. Do I need to go back to glasspacks or a less restrictive muffler, or can I go to a quieter muffler?

The kit:
https://www.speedwaymotors.com/DIY-U...-4,284231.html

[cwcarpenter98]

I run a Black Widow Exhaust Venom 250 with my 283, and I absolutely love it. I have the stock ish looking pipes (2 inch) for the whole way except for the muffler that is a 2.5 inch. I love the sound it makes when I floor it, and even better is that it does not seem to drone at all. Black Widow sells mufflers that are louder than the Venom 250, but for me, I like the quite sound in the cab at cruising speed, and when I floor it, she wakes up and gets loud. I have not heard what it sounds like outside of the truck when I floor it, but my friends say its pretty loud. Hope that all makes sense

[vin63]

Where/location did you mount the muffler (under the cab, under bed, etc.)?

[Indian113]

Do you have a X or H pipe built into your exhaust? I put a H pipe in mine and lost the drone.

[Chevy Fleetside]

When the exhaust was put in my truck, the exhaust guy put in two resonators. I am running 2 1/2" exhaust with Flow master 40's. At first it was really quiet but now sounds real nice. Not to loud and not to quiet. I also had a cross over pipe installed. This is with a Big Block.

[njc1230]

Hi guys, thanks for all the responses. With the short wheelbase, the mufflers are underneath the cab, and theres nothing in the exhaust system other than the mufflers. No x pipe, h pipe, resonators, etc. I found these mufflers from Walker on Summit called "SoundFX" that are supposedly really quiet and Im considering putting those in. Yes, they wouldnt be the best for performance, but its already plenty fast for me.

https://www.summitracing.com/parts/wlk-17808/

[vin63]

Before spending money on another set of mufflers, try moving the mufflers as far back as possible under the bed (out from under the cab).

[bigmoe]

A buddy told me a lot of newer exhaust systems have weights clamped to them to decrease drone. Might be worth investigating.

Edit* If you google 10199232 you can see a pic of a dampner GM used in the 90's.

[PGSigns]

Put a H pipe in it. Made a world of difference in mine.
Jimmy

[jayoldschool]

Originally Posted by njc1230

Hi guys, thanks for all the responses. With the short wheelbase, the mufflers are underneath the cab, and theres nothing in the exhaust system other than the mufflers. No x pipe, h pipe, resonators, etc. I found these mufflers from Walker on Summit called "SoundFX" that are supposedly really quiet and Im considering putting those in. Yes, they wouldnt be the best for performance, but its already plenty fast for me.

https://www.summitracing.com/parts/wlk-17808/

The muffler location and the dumps are 100% the problem. Mufflers need to go under the bed, and the exhaust needs to exit behind the rear wheels. Your problems will immediately disappear.

[mongocanfly]

Resonators will help as well