• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Repacking the muffler

Share this page

The acousta-fil expanded nicely. Too bad the muffler's almost as loud as when it was empty. In view of the crack at the back and the apparent weakness of the muffler exit stub, I decided not to install the stock tailpipe -- it had a crooked end on one of the pipes and I'd have to torture the muffler to get it in there.

So I've said the h*ll with it, discontinued the experiment and ordered the Moss Tourist Trophy.

screenshot.1193.jpg
screenshot.1192.jpg
 
Hi Steve,

I wonder if the density of your packing is too great or restricting the gas exits? Since the sound waves are carried on the exhaust flow and the flow needs to be interrupted to break up the waves.

As I see it, if the diameter of the Perforated Pipes are such that it can easily handle output flow and the density of the packing further retards gas passage through the perforations, the uninterrupted gasses will take the path of least resistance and carry the uninterrupted sound waves.

Have you tried reducing the packing density or restriction exit flow? These actions could allow more gas diffusion through the perforation and through the packing and change the sound waves by increasing gas exit speed.

Keep in mind that these are only thoughts with little direct supporting experience,
Ray(64BJ8P1)
 
steveg said:
I actually think it's due to my 1.75" tailpipes left over from my Monza exhaust. ...
Click to expand...

Steve has indirectly--I think--made a good point. The sound of an exhaust isn't only due to the type of muffler--'turbo' or 'glasspack'--or the packing, but to the material, thickness and diameter of the piping. I've attributed the sometimes 'tinny' sound of SS pipes to the SS--they do seem to mellow with age--whereas mild steel systems have a mellower sound from new. The Ansa exhaust I had on my BJ8 was well made and fit perfectly, and the pipes were so thick I'm still using them on my cobbled together 'frankenmuffler' with hot rod glasspacks. Most exhausts, I think, are made from 18 gauge steel, but I wouldn't be surprised if some manufacturers are skimping on this which can make for more noise.

The Ansa system and, I think, Monza systems are unique in that they have small glasspack mufflers at the tip. I always thought they made the BJ8 sound like half of a Ferrari, but I couldn't resist cutting the tips off and keeping them for, well, I'm not sure, but I couldn't bring myself to throw them away.
 
John,

Giving a Poodle a hair cut during a NJ winter could stop the snoring...for good.

As I see it, a muffler functions by causing the air stream to be diverted in order to help brake diminish its ability to be a transport of sound waves. This function has been done in many ways and having the flow pass through the fiberglass packing would perform that function. However, having the packing too tight and the internal pipe openings too small could physically cut down the amount of gasses passing through the packing and cause a much higher of non-diverted flow to not pass through the packing. My thought was that, assuming you can't redesign the internal design of the muffler, then maybe a less dense packing could allow a higher percentage of the flow to be passed through the packing and disrupt the path of the sound waves.

Where is my logic incorrect?

Just my thoughts,
Ray(64BJ8P1)
 
Bob_Spidell said:
The Ansa system and, I think, Monza systems are unique in that they have small glasspack mufflers at the tip. I always thought they made the BJ8 sound like half of a Ferrari, but I couldn't resist cutting the tips off and keeping them for, well, I'm not sure, but I couldn't bring myself to throw them away.
Click to expand...

The dual stainless tips the muffler shop put on my car had too large a diameter and looked a bit like twin bazookas:

IMG_0342_zpsvifry6wh.JPG


I was able to find some NOS ANSA tips with resonators here: https://maseraticompound.com/collections/ansa-exhaust-tips-and-parts which looked a lot more like an aftermarket Healey exhaust and quieted down the really loud V8 sound:

 
The packing around the outside of the tubes is the expanded single layer of acousta-fil -- that's how it puffs up when you run the engine for long enough for the containing fibers to melt away.

I may take this further in a year or two, but for now am just going to store this system and install the Tourist Trophy.
 
Re Supertrapp: funny, in that we have a supertrapp clone on our Meyers Manx clone dune buggy, and it sounds like a 4 cylinder British sports car instead a VW beetle engine - which I prefer. I've got an old Buell motorcycle that the PO had put a Vance & Hines aftermarket exhaust on, then took out the packing plus bashed out everything that was useful to repack. I replaced some parts plus found a 'blanket' type material for the muffler. At idle, it's pretty much the same as a stock Harley (same engine), as well as at higher rpms. I don't like noise; I particularly don't like obtrusive noise, so am reasonably content with the loudness/lack thereof of both vehicles. Doug
 
I've installed the Tourist Trophy. It's loud when you get on it, but overall quieter than any of my other setups, especially at cruising speeds. Fit is good and kudos to Moss for their adjustable mounts which make it easy to center the pipes on the bumper overrider. Shown here with my uprated compression-type rear mount.

screenshot.1207.jpg
 
Steve, I agree with your kudos to Moss Motors for doing the work to produce a beautiful piece of kit that is easy to install and both looks and sounds great. Years ago I swore I would never again install a muffler system or mount a tire. I would leave those tasks to the pros. Well, I took on the Tourist Trophy unit and was pleased with the results.
Still don't do tires.
 
Having followed this post with interest I have also decided to abandon the repacking route, however would like to keep the AH side exhaust but perhaps re model the pipes for a rear exit hence keep the decibels but they would be behind me. I have an exhaust guy who could do this but would like to know if anyone out there had done it and if we could maintain a good ground clearance.
 
4tecdog said:
Having followed this post with interest I have also decided to abandon the repacking route, however would like to keep the AH side exhaust but perhaps re model the pipes for a rear exit hence keep the decibels but they would be behind me. I have an exhaust guy who could do this but would like to know if anyone out there had done it and if we could maintain a good ground clearance.
Click to expand...

Not quite clear on what you mean - could you clarify? Out the rear is stock. It is quieter than side exhaust.
 
Yes Steve I have S/S side exhaust at the moment I think it is an AH spares one it has twin boxes, I was wondering if I modified and lengthened the pipes at the rear of these boxes to exit the rear of the car this would make it quieter in the cockpit so I could hear the good lady. I do have a good exhaust guy who bends S/S pipe and I was wondering if anyone else had taken this option with a Healey and if so how they had routed the pipes around the rear axle to give reasonable ground clearance. I was originally contemplating packing the boxes with acoustic wadding, modifying the exhaust or biting the bullet and fitting a new Moss system I already have a modified exhaust manifold (header) so I don’t know which one to go for.
 
Wel: 4tecdog

The sound of the original exhaust system has been altered with your existing changes..
Assuming you add new straight SS pipes to the boxes will alter the frequency response of the system.
Moving the exhaust point farther from your ear by routing the pipes out the back will attenuate the power level of the sound.
However, it could move the frequency of the sound in a direction where your ear is more or less sensitive.
I would move it as described and see, in any event the " Decibels " may change
 
Back
Top