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I need to get mufflers and tailpipes now that the engine is back in its mount (’35 Model 845 Eight). The literature is confusing – the brochure copied in the “Arrow” 78-1 talks about “triple” mufflers, but the specs and parts books only refer to two. The picture of the chassis in the “Arrow” shows 2, can’t tell if there might be some resonator hidden next to the gas tank. My original has two mufflers but the short one was put behind the long one, opposite of what the picture shows.
I assume it is really just two mufflers with the short in front of the long and someone turned mine around backwards?
Is the reference to triple mufflers implying the long one is two mufflers in one?
Is there a noticeable difference between sound of the 36’s with four mufflers and the 35’s?
Thanks for any help.
Jim
Hello Jim, I’ll bet you can’t wait to get your engine fired up, and running nice and quietly. Joe Malone looked into the correct muffler setup for his and my ’33 836 Club Sedans. We found several discrepancies between advertising, parts lists and actual ‘original’ cars.
I’m assuming a similar situation exists for you ’35 845.
From the many old and partially complete exhaust systems I have or have examined, the original system had a short ‘resonator; under the engine splashpan. This resonator would be directly below the fuel pump, and no doubt contributed to vapor-lock when running the cars in hot weather.
After the resonator was a short pipe with a slight ‘S’ shape then two more straight mufflers, with a short connecting pipe between them.
The rear-most muffler ended just before the tail pipe kicked up and over the rear axle, and under the fuel tank, then out under the rear bumper.
I’m sure that as the cars aged, an exhaust system was used that cost less than the factory system, So the three muffler/resonator system gave way to two or eventually one muffler.
I’ve done quite a bit of experimenting with exhaust design and exhaust sound. I’ve found that each time the diameter of an exhaust component changes size and returns to a pipe, even a short connecting pipe, the exhaust sound mellows and the engine exhaust is quieter.
As ‘proof’ of this, I compared my three 8 cylinder cars exhaust systems and sound when running. Both of the single muffler systems were noticeably louder and had a sharper or ‘raspy’ sound.
The third car however backs up my experiences with multiple muffers.
The third car, a 1932 8cylinder car, has an exhaust system that has a 2.25″ exhaust pipe from the exhaust manifold back to the first 2.25″ straight-through resonator, then several feet of 2.25″ exhaust pipe, then a second 2.25″ straight-through resonator. Both resonators are about 18″-20″ long. After the second resonator, the tailpipe is 2″ diameter and follows the normal route up and over the rear axle then under the right hand lower corner of the fuel tank.
Even though my two cars with single muffler systems have bypass-type mufflers, which should lower the exhaust sound considerably better than a straight through resonator, the two-resonator system has a much more mellow exhaust sound, and lower overall volume of noise.
I spoke with an exhaust sound engineer who worked for one of the ‘big three’ in Detroit. He told me that the exhaust has pressure pulses in the air flowing or being pushed through the pipes and mufflers and resonators. I was told that when the pulses expand to fill a canister like a muffler or resonator, that the noise-pulses get disrupted, then are not able to restore the same pulse or pressure wave in the air flow as the air is leaving the muffler or resonator, and back into a simple pipe. I was also told that changing the diameter of the exhaust pipes, and hence the diameter of the column of flowing air, changes the shape and integrity of the noise pulses in the air flowing towards the tailpipe outlet.
Without hearing the actual results of the three systems, if someone had described the systems, shown a cut-away of each muffler and resonator, I would have expected to have both of the single muffler systems to be quieter than the straight-through system with two resonators. The inside of the resonators is just a 2.25″ tube with 1/8″ holes drilled, spaced about 3/8″ apart. I can read a manual or a book looking through the resonators.
Jim, I’m sure that if you find two mufflers or resonators, that will fit in the space you have for your exhaust system, connect them with at least 6″ of regular exhaust tubing, then a normal tailpipe over the rear axle and out the back of the car, you will be happy with the resulting mellow sound and low noise levels.
The original mufflers had a double wall outer skin. This was a second layer of steel, welded at the ends with a few spot-contact areas along the length of the muffler that had welds holding the outer skin to the inner skin. I remember finding some form of thin woven insulation between the two layers of steel skin on a couple of mufflers. This probably was asbestos.
If you are interested in trying to make a muffler itself resonate less noise from it’s outer surfaces, you can wrap the muffler with fiberglass ‘header-wrap’. This ‘header-wrap’ is available from most auto-supply stores and mail order stores like Summitt.com. A second outer steel skin can be applied over the fiberglass wrapping to help protect the fiberglass wrapping from fraying. I’ve done this ‘experiment’ and there is some change in the quality of the sound resonating from under the car or truck. I’m not sure it was worth the effort though. Your results may be considerably different.
I hope this sharing of my ‘exercises in muffling’ help you with finding and using an exhaust system for your ’35 845 Pierce.
Greg Long
In 1976 I purchased a very original 840 sedan. The original exhaust system was exactly as described by Greg in his paragraphs three, four, and five above.
At the time I was able to find an exact replacement system, and the car sounded great, quiet but still a nice subtle exhaust note.
Thanks! I am anxious to fire this thing up, but still months to go. I have all the ancillaries to deal with: carb, fuel pump, radiator, starter, generator, water pump, etc.
Looking at my mufflers it looks like the original pipe from the manifold was 2 1/4 and cut at the bottom of the bend, probably to replace the first resonator. Seems like a crowded space near the fuel pump, do you know what the dimensions of it were? Presumably less than the 6″ diameter like the two behind it? I have routed my auxiliary electric pump lines on the outside of the frame because of the vapor lock worry.
I do plan to wrap everything with the high temp manifold wrap, I cooked my wife in the Packard years ago because the pipe passes under the passenger side, she wasn’t a happy camper so I did lot’s of insulating after that.
I appreciate your comments, I do want to make this car very quiet between the hydraulic lifters and muffler system.
Thanks again!
Jim
Hi Jim, here is a photo of an original [I’m 90% sure[ resonator on a ’34 Pierce Arrow.
This photo was taken looking straight down the side of the engine.
The original heat shield is on the vertical portion of the exhaust pipe, and the resonator is quite short, It is shorter than I remembered seeing in the past. Since the exhaust pipe is 2.25″ diameter, so it looks like the resonator is 6″ in diameter. but if I squint just right, it might be 5 inch diameter. The most important diameter is the inside diameter of the pipe inside the resonator, it must be a minimum of 2.25′, a bit larger would be better.
Greg Long
Thanks! This is a great help. I can put this in my CAD program to take the measurements. My exhaust pipe has the heat shield and was cut just behind the bend before the resonator with a 2″ pipe welded in behind.
Jim”
I enjoyed reading this topic today, I offer one suggestion based on my professional experience.
Be careful in insulation of or wrapping exhaust piping on 4-cycle engines. If the piping is not stainless steel, there is a temperature limit beyond which the piping will rapidly deteriorate and turn into large flakes of rust, and 4-cycle engine exhaust is capable of being at or above this limit. It literally burns up. We make exhaust piping for 4-cycle engines from stainless steel as it can withstand operating at higher temperatures as it will when insulated, as it often must be inside the buildings. A good alternative is radiant heat shielding. A piece of aluminum sheeting strategically mounted between the piping and the floor of the car, for example, will provide protection form heat without increasing the operating temperature of the piping.
Again, I enjoy reading all the technical topics as I try to learn enough to deal with the Car I hope to get one day.
Greg, I measure the resonator in your picture at just under 6″ OD and 12″ long. Thanks again!
Stainless of course will always outlast. The Pierce specs for ’34 say the mufflers were insulated with asbestos lagging, and there is an asbestos insulator attached to my passenger side floorboard. Forgive the un-authenticity of it, but I think I will replace with non-asbestos insulation! Perhaps the original resonator is actually a 5″ with asbestos insulation and an outer cover.
One of the problems with collector cars rusting out mufflers and tailpipes is the tendency to run them on very short drives without getting the exhaust system hot enough to evaporate the water, leaving condensed water and carbon in the low spots. This is an ideal combination for rusting of steel. I drill small drain holes in the lowest points of mufflers and tailpipes. I don’t know if it does any good, but it makes me feel better.
Jim
If the piping was insulated or wrapped from new, you should have no problem with insulating it. There are some very good, non-asbestos, insulations available today at reasonable cost.
You are right about not getting the exhaust system hot enough to dry it out. Exhaust contains quite a bit of water vapor, plus some acid. Imagine that for a harsh environment.