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I just finished getting the 3 mufflers and tailpipes installed on my ’35 845. Here are some notes to hopefully help others not make the mistakes I just did.
There are inconsistencies in the muffler specs for ’34 840 and ’35 845’s. Pierce specifies 73” total case length for all three mufflers combined without giving details on the breakdown of each. I estimated in various ways that the #3 was somewhere between 35 and 37”. Actually installing it indicates it was no more than 36” case length as that is the limit on 139” wheelbase to fit between the mid frame crosstube and the rear shock absorber. The outlet on #3 needs to be offset – not centered. I ordered mine as centered, which doesn’t fit correctly. There is a very narrow window coming out of #3 to thread the tailpipe between the rear shock and the rear brake shaft support and also keep the rear brake cable from hitting the side of the muffler. I had to drop the back end of my #3 muffler so the tailpipe passes a bit under the rear shock instead of next to it.
A picture kindly supplied by Greg Long of an original #1 muffler (Pierce called it a “synchronizer”) measured out at being 13-14” long and the same 6” diameter as the other two. The 14” length fits fine, but the clearance for a 6” diameter is very tight. One of my current paranoias is vapor lock/fuel boiling trying to restart a hot car. Heating of the fuel pump by the hot exhaust system after shutdown is a major contributor to vapor lock, so the location of the fuel pump right above the #1 muffler is of concern and I had planned to insulate it with muffler wrap. Pierce originally had a thin layer of asbestos insulation inside the mufflers based on both Pierce specs and pictures of the insides of a rusted original provided by Bill Lyons in a previous post. I substituted a 14” case length 5” diameter glasspack for the #1. Pierce’s original muffler system was designed to have minimal restriction by having straight-through perforated pipe mufflers similar to glasspacks. 3 mufflers were used in ’34-‘35’s (4 in the ’36-‘38’s) of different lengths apparently to damp different frequencies allowing a quiet exhaust with minimal restriction. I am hoping that going to the glasspack for #1 will provide a lot of thermal insulation (via the fiberglass) to cut the heat flow into the fuel pump while still having some noise damping like the original. The replacement mufflers that were on my car when I got it left the #1 out completely and just had a (small) pipe to the other mufflers. I think this is common on a lot of Pierces.
Just stringing 3 conventional baffled mufflers together would probably result in more backpressure than the Pierce system. The #2 I believe was a 24” case length straight-through. I found a 26” straight-through perforated tube muffler for #2. It splits the flow between two perforated tubes but does it without baffles or changing flow direction so its restriction should be minimal.
The #3 muffler I ordered from Waldrons as it was the only source I could find for a 36” long muffler. As I mentioned, I should have ordered it with an offset outlet. I also ordered it with “OEM” sound. In retrospect I probably should have ordered it with more “aggressive” sound for less backpressure since there are already two mufflers ahead of it.
John Cislak has been collecting factory mufflers and pipes for more than twenty years. Several years ago he manufactured exact reproduction systems, and he has since sold out of them except for the 36 to 38 V-12’s. The factory mufflers were double wrapped and had a series of baffles, but the system was not restricted. The system was 2 1/4 the entire length. It had mandrel bends, and the fit was very tight to the frame and chassis components when new. The systems were very quiet, and almost sound like a jet engine in the distance. I would describe it as a gentile fan or whir that spools up. Almost a gentle whine. All mufflers today are single wrapped, and thus cause a tin ringing sound. Most mufflers available that we purchased from modern suppliers were more restricted, and only available in two inch. I can state that most cars I have seen or driven with the modern mufflers are too restricted, and under sized as far as the pipes go. The latest car we restored got one of the factory duplicate systems, and the car performs better than any other Pierce I have driven. John is not going to do the project again, as it was just too expensive for most people. It was fun to listen to the car, and explain to people the system is a factory duplicate and thus th car sounds like it did when new. As a general rule of thumb, run the largest and least restrictive system you can, the car will perform better. Ed
You are right to be concerned with heat and vapor lock; after all vapor lock is caused by gasoline boiling and this is heat and low pressure (vacuum). I would not wrap the fuel pump with insulation, tbough: remember it is exposed to crankcase heat and hot oil already so it needs to shed as much heat as it can. Rather, concentrate on a radiant heat shield between the exhaust parts and the pump. Be sure all you higher-volitility, “winter” gas is gone beforeyou start touring in the warmer months.
Exhaust system design is somewhat similar to the design of suction and discharge piping for natural-gas compressors. It uses choke tubes and other “tricks” to smooth the pressure impulses and dissipate the energy which creates the objectionable sounds. In the case of compressor piping we are trying to reduce pulsation-induced piping vibrations and energy-wasting pressure drop, but it’s all tradeoffs and a balancing act.
One might think a car of the Era with an engine of similar size and configuration would have a similar exhaust system.
I have been using tractor mufflers on my Morgan’s and they have some 2 1/4″ inlets. I was going to see if they may have something that fit. I am pretty sure they are not double wrapped, but they look kind of period correct.
Since the Morgan’s TR engine is Ferguson tractor derived, I think is appropriate.
The mufflers on my 845 when I purchased it had obviously been replaced, necking down to a 2″ pipe replacing the #1 muffler and then using a 1 3/4
tailpipe instead of a 2″. My replacements are all 2 1/4″ diameter inlet/outlet and a 2″ dia tailpipe per the Pierce spec. Trying to snake that 2″ through the obstructions was a big challenge and I can see why the long forgotten muffler shop made life easier on themselves and used a smaller diameter.
I am in the process of reviewing old SAE engineering reports on vapor lock and in particular the effect of modern fuel properties including ethanol. Randy you are of course absolutely right, the last thing you want to do is insulate the outside of the fuel pump, it would make vapor lock worse by restricting air circulation. The thick insulating gasket is critical to reduce heat coming from the block. I think improving ambient air circulation around the pump and carb is the right direction.
My #2 is a heavy duty truck muffler much thicker than typical. If my ’35 survives initial start and driving the bare body/chassis around without a problem I will wrap them in muffler insulation for the next phase.
I would like to hear a Pierce with the original muffler design – I have been curious for 20+ years.
If I were as talented and dedicated as Jim Livings – who makes his own mufflers – I would replicate then myself, but too many skills to learn for a single car project!
Jim
Check out the Stanley Muffler web site.
One can search muffler sizes by inlet, outlet diameters and body length.
I would think one would find a muffler that has the right dimension although the end construction may look different. Stanley makes replacement mufflers for agriculture and industrial applications and will even make custom mufflers.
Ed, John Cislak obviously made a significant investment in reproducing mufflers years ago, but if he doesn’t intend to produce them again do you think he might consider publishing the specs from the originals?
Jim
He never made drawings, he sent the original pipes and mufflers out to the manufacturers. Give him a call, I am sure he will be happy to assist you.
Ed, too late for me at this point, I have what I have and going to live with them, but maybe the next guy.
Thanks! Jim
Sorry to keep bringing this up -maybe I’m obsessed- but I found (too late for me)wonderful pictures of the installation and arrangement of the 34-35 mufflers (perhaps also applies to ’33?). 21 years ago I squirreled away the 1995 model 4 issue of “The Arrow” that shows all three mufflers and the interconnecting pipes on a long wheelbase. It also shows the internal construction of the front and rear mufflers that of course agrees with the remains of the original muffler posted by Bill Lyons. These could be used to reconstruct new mufflers to the original design if someone has a mind to do that in future.
Unfortunately, when I was trying to figure out mufflers for mine I stopped short of pulling this issue out after I found a less detailed set of pictures in a different “the Arrow’ I had squirreled away.
One of the problems of delaying a restoration project for 20 years. Oh well!
Jim