GMC M211 muffler and exhaust build

[hendersond]

This is a thread dedicated to the G749 series muffler. My goal is to collect data and then produce a decent replica of a factory muffler that can be made with common tools found around the shop.

I have one good muffler that Maccus (A great guy) picked up from a great guy in South Dakota. I need more information. Most importanty, pictures.

Pictures of the inside of a bad muffler showing the "guts" will take us in the right direction.

From there, I will bend the pipes and post the bend information. My goal is to have dimensions available so anyone can take the information to an exhaust shop and have the pipes bent.

The time line is muffler done in October and pipes in early November.

(I want my truck so quiet the wife wont hear me come home from deer hunting.)

 

[firefox]

Wow, talk about dreaming big! Wives have big ears, and they can read SS posts
so be very careful.

Oops, I thought you said dear hunting.....

 

[hendersond]

I got this PM from a super secret SS member:


I am on the hunt too for a muffler and stack for my m221. Seems there is a renewed interest in these trucks.

Below are the "specs" for the muffler:


Overall Length29.125 inches nominal
Overall Height10.125 inches nominal
Overall Width6.125 inches nominal
Inlet Connection TypeUnthreaded
Outlet Inside Diameter2.250 inches nominal
Design TypeDRY
Coolant TypeAIR
Muffler DesignBaffle
Baffle Quantity2
Tube Quantity1
Body ShapeOVAL
Operating PositionHorizontal
Inlet LocationCentrally located on horizontal center line 4-13/16 in. from end of body
Inlet Projection Length2.250 inches nominal
Inlet Outside Diameter2.625 inches nominal
Inlet Inside Diameter2.500 inches nominal
Outlet Connection TypeUnthreaded
Outlet LocationCentrally located on horizontal center line 2-3/16 in.from end of body
Outlet Projection Length2.250 inches nominal
Outlet Outside Diameter2.625 inches nominal
MaterialSteel
Surface TreatmentAluminum
FSC Application DataExhaust system, engine, non-aircraft


Hope this information helps! I dont even have an old one to go by.

 

[tlmob1]

Great info.

 

[Gunfreak25]

I ran across a post 2 years ago of a member here who reproduced one. Time to exercise my google fu, in which I carry a blackbelt.

Edit: I found the post but it appears you already did as well.

 

[hendersond]

Called a friend of mine today. Seems he needs a big metal lathe and I need a exhaust bender. He has a bender, I have a lathe with a 18" swing. We are going to trade equipment for a few months. This is GOOD!

 

[hendersond]

I have a new idea. I had ordered a special Donaldson muffler back in November. It still is on back order, so I cancelled it. I just purchased a Walker 21324 for $67 on ebay. It is a super quiet 24" long muffler with the inlet and outlet on the same end. I will add 2 elbows and flanges. It will work to get the connections in the correct location, just not original. The pipes are actually 2" diameter. After doing a little research when I was younger on a 1980 Malibu wagon with the throttle to the wood (and some other bad choices) I know 305ci will flow thru 2" exhaust. I assume it will do just fine with 302ci at 2800rpm.

I also found a 2" x 12" stainless steel double braided flex pipe on Ebay for $20. thei will make the connection from the muffler to the stack.

I also considered these mufflers with the inlet and outlet on the same end:

Magnaflow 14210 muffler at $130 this has 2.5" inlet and outlet
Flowmaster 52580 muffler at $130 this has 2.5" inlet and outlet
Walker 22637 muffler at $88 this has 3" inlet and outlet.

I figured the walker 21324 would be the quietest. It came on 97-03 chevy malibu and they were quiet.

I'll post pics later this week when the stuff arrives.