VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 '37 Muffler Dimensions

I am planning to have a local shop fabricate the exhaust and tail pipes for my '37 Master Coupe (GB). I have the complete old exhaust system but it has a glass pack muffler. My search gave me some of the stock muffler information I need but there are still a few things I need to know.

I know that the inlet and outlet are sized for 1 3/4" pipe and are offset to opposite sides. The overall length of the muffler including the inlet and outlet is about 21".

What is the approximate diameter of the muffler?
What is the length of the muffler body? My estimate is about 17" or so.
Do the inlet and outlet on the muffler fit over the pipes or are the pipes expanded and fit over the muffler connections?

Thanks as always!

The exhaust pipe slips inside of the muffler pipe. The muffler pipe is 2" O.D.
The tail pipe is on the outside of the muffler pipe. The diameter of the muffler rear pipe is 1 11/16" 2" I.D.
A muffler shop can expand a pipt to fit.
As far as I can find the mufler is about 17" , measuring the main body.

Hello Rusty 37 Master,
CoF's has the stock muffler for your car. I purchased mine from them and had a local shop bend up the pipe. My car is extremely quite.

Diameter is about 6". I had a muffler thread a couple weeks back and there are a few sources of mufflers in that thread.

The prices are all reasonable so might be worth getting the muffler first, then heading to the shop.

Thanks for all the details and advice. Great info as always!

Want to get this thread active again and try to close the loop on this.

Yesterday I received what is supposed to be a "replacement stock" muffler for my '37 Master Coupe from Chev of the 40's. I think I just wasted $100!

The overall muffler size (6" diameter, 17" body length. and 22" overall length) is fine. Chev of the 40's buys a NAPA part 18135 muffler and has a local shop expand both the inlet and outlet. Walker makes a similar muffler.

The original inlet size is 1 3/4" inside diameter. They have that expanded to snugly fit over the 1 7/8" outside diameter of the NOS exhaust pipe I have. Great!

The problem is the outlet. The original outlet on this muffler was 1 3/4" inside diameter. They have expanded that to 1 7/8" inside diameter which gives about a 2" outside diameter.

Based on the tailpipe on my car and the information in the Master Parts Catalog, the tailpipe is 1 3/4" OD and it slides over the muffler outlet which is about 1 11/16" OD. When I called Chev of the 40's they told me that their data shows the '37 had a 2" OD tailpipe.

So now I have a worthless muffler unless I want to add a bunch of adapters and unnecessary size transitions and extra joints. The easy way out is for me to buy a new 18135 muffler from NAPA ($50) and have the inlet expanded to fit over the exhaust pipe. I will leave the outlet as is and fit it over the 1 3/4" tailpipe instead of fitting the pipe over the outlet.

What am I missing? Was it really a 2" exhaust?

Hmmm. Everything was under 2" that I have read and you definitely want the tailpipe larger than the outlet to go outside of the connection.

http://waldronexhaust.com is who I plan on using and yes, I plan on ordering all of the pieces just in case someone, somewhere has the wrong measurement. These variances have always stressed me out as unless they all come from the same place at the same time, even a 1/16" diameter difference can cause you pain...

You could get a new tailpipe bent since you have the old one, just with larger diameter pipe or have the tailpipe welded INSIDE the muffler outlet so no leaks.

The muffler tail pipe outlet is 1 11/16" and the tail pipes were 1 3/4" OD.

Hi Tim and Gene,

Thanks for the information and confirmation about the tailpipe size.

If the muffler outlet is too big the stock hanger will not fit. That hanger is made to fit the 1 3/4" tailpipe. So adding adapters and bushings creates another set of problems.

There are 3 reasons I am planning to have the tailpipe made locally.
- Unless you pay a lot for extra shipping the tailpipe will be made in 2 pieces.
- We can make sure it fits properly.
- Spend my money with local businesses.

The search for an appropriate muffler continues!

It's always an education isn't it...

I plan on using Waldron mainly because they make their own mufflers in 3 different "noise levels" within the stock looking muffler body - Stock, mild and louder. I can't stand quiet exhaust so need some tone so may buy 2 different ones to test.

All are available in either aluminized or stainless.

I will likely buy the cheap tailpipe in 2 pieces and then have a local shop copy it as a one-piece once I've tested fit as I don't have an original to use as a template to get the "look" correct. I already get killed on shipping so the price of the 2-piece tailpipe is minor for a sacrificial template.

I want to build my chassis fully before dropping the body back on so can't drive it to a shop though I'm sure I'm not the only one who in their youth drove a car while sitting on a milk crate while using vise-grips for a steering wheel???

Hi Tim,

Here is a crazy idea! When I remove the tailpipe from my car I will trace a full size template on a long sheet of white "butcher paper". Based on my observations the bends in the tailpipe are almost all in one plane. I can even do it in 2 views!

Easy and cheap to mail to you and will maybe save you ever buying the 2 piece tailpipe.

LOL!

If all the bends are on one plane that would work, even accurate measurements/sketch might work great too. I've seen the dimensions in a couple parts books but they always seem to be missing some dimension if I recall.

Alternatively, you could add index marks to yours, cut it into 5 x one foot long pieces and ship them to my buddy's US PO box lol so you don't have to measure, just cut.

The cut apart approach should work pretty well also. With index marks and a few labels you can "reconstruct" it!

How to import a car in small pieces bit by bit...

If you notice any areas on your exhaust where clearance is tight, it would be nice to see some pictures of the area so I could allow space since I'll be assembling without the body in place.

I followed this thread with interest because the muffler of my 37 master deluxe driver is cooked but the pipes are in good shape. Its now on blocks for the winter and it's time to act. Any suggestions on how to remove the muffler and keep the pipes in place using home shop garage / hand power tools ?

You could use a small angle grinder with a thin cutoff wheel to disassemble the muffler itself and carefully slit the muffler inlet and outlet so you can pry them away from the pipe ends. Just wear goggles and don't use the trigger lock while on your back under the car. I got chased by a grinder doing this exact work 40 years ago..

Follow-up, Removed the muffler with saws-all, cold chiseled off rusted muffler pipe remaining on exhaust pipes. A little damage to the outlet pipe with interior muffler fit inside but workable. I bought the NAPA muffler noted above + 2 adapters and clamps. The intake adapters fit well. In my case 1 7/8" ID to 1 3/4" OD. I had a problem finding a fit for the outlet side but used a 1 5/8" ID to 1 5/8" ID that fit snugly inside both outtake pipe and muffler outtake. Not kosher I know but no indication of leakage. The original manifold connection was a custom fit with flange & gasket and inside pipe extension that ran an inch or 2 into the manifold. I replace that setup with "compressible beveled donut" and it's all holding tight. Lessons learned; The adapters added length to the system so initially the outtake pipe hit the gas tank. A little saws-all surgery to the system corrected that and aligned it to the original hangers. I also found that a 1 5/8" ID, 1/16" thick adapter is a tad larger than a 1 3/4" OD. Got my safety sticker, she's back on the road. Thanks for the comment It got me motivated to get it done. .