Muffler Report

kevinshea

kevinshea

Senior Member
The muffler on my 35 wagon popped open on a backfire, it was repaired but did it again.. I tried to find a replacement (NOS or equivalent) but couldn't. So I consulted with a muffler guy and we found an available unit that fit in the tight space (17" shell).. New unit is noticeably louder and it seems to have some back pressure based on the need to gas the engine more than I did previously.

So, I am on the lookout for a stock 35/36 -- some suggest that 34 works.
 
Since it is louder, there is less back pressure. With less back pressure, you can get a lean condition. The less restrictive mufflers allow more air to flow through your carb with the same amount of fuel being added so the AFR is higher. You can test it easily before changing jets by just pulling your choke out a little to see how that works.

Many of the Harley guys with open or close to it pipes, get popping and poor performance due to this and also pressure waves going back into the motor. All that is important is being LOUD ;-0
 
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I have Brockman mufflers on my modified 59A and got some popping. Having three motorcycles, I knew I needed to add a little back pressure so I slipped in 8" long X 1-3/4" baffles into each exhaust tailpipe and problem solved.

587097


587098
 
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have some popping in the exhaust and created a thread a few weeks ago about it. i eventually ordered a system from Waldron. it should be here soon. i'll post a comment when it's installed WRT the popping. i bought the bog standard one.

https://waldronexhaust.com/
 
The muffler on eBay sort of looks like the Truck version (51-5230) but I could be wrong. The inlet and outlets are in different orientations to each other for car/pickup versus truck.
 
the one against the cabinet is a 48 prefix script muffler the other one is a aftermarket one from the 80s
 

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kevinshea said:
The muffler on my 35 wagon popped open on a backfire, it was repaired but did it again.
Click to expand...

You may have ruptured the power valve diaphragm too.

"Ruptured power valve diaphragm is the most common internal damage to a Holley 94 carburetor caused by backfiring. This failure allows fuel to drain from the bowl into the engine intake, potentially causing rough running or stalling, although some users note this specific design is less prone to rapid drainage than other Holley types."
 
Glenn... Great observation about the backpressure/noise connection. I understand the AFR and how to modulate either fuel or air.. choking wll be my first test (but the rain in Maine is delaying those efforts), and then, rather playing with jets, I can replace the 94 carb .. I have 3 of them, all rebuilt... easy to swap out and continue the testing..

I did get is out on the highway and ran it up to 55/60... the issue of tire induced shake seemed to diminish... hopefully after warming, the tires are reverting back to original condition.
 
When we were teenage know-it-all wanna be mechanics we would spray water from the garden hose into a hot muffler through the tail pipe to destroy the contents. Cheaper than a new cherry bomb muffler.
Just don't rev the car up to blow it out while it is in you dads driveway About an hour for three knuckleheads with scrub brushes and a can of Comet cleanser to clean that mess up. LOL Chap
 
Glenn: Go the 35 out and played with the choke... I can definitely see a difference in performance, particularly acceleration. Seems to generally run smoother. Feels like it did prior to my long term storage. Still don't like the noise from the new muffler. Thanks for the advise. Next test will be to change out the 97s.. but since I don't know the jet sizes, nor do I have a jet tool, it will be a game of simple changing out and playing with the choke - as needed. I will get a tool as needed.
 
kevinshea said:
Glenn: Go the 35 out and played with the choke... I can definitely see a difference in performance, particularly acceleration. Seems to generally run smoother. Feels like it did prior to my long term storage. Still don't like the noise from the new muffler. Thanks for the advise. Next test will be to change out the 97s.. but since I don't know the jet sizes, nor do I have a jet tool, it will be a game of simple changing out and playing with the choke - as needed. I will get a tool as needed.
Click to expand...

Good!

Make it simple, slip in a motorcycle baffle, https://tinyurl.com/2jkuxkxr For ~$20 or make some "lollipop type" baffle if you have a welder.

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Regarding the '97s, I have an AFR gauge and did lots of fiddling and ended up with this, https://www.fordbarn.com/forum/showthread.php?t=350547&highlight=jets

"From Uncle Max, re. dual 97s:
https://www.jalopyjournal.com/forum/...t-jets.419923/
"I don't believe in adjustable jets. (where's the baseline?)
I do believe in marrying the right jets with the right powervalves, remembering that a properly functioning powervalve starts to enrich the mixture at about 1/2 throttle - due to the "hydraulic" action of the accelerator pump, and becomes fully open at the end of the stroke. I also believe, for your flathead, assuming your're not planning to do much driving in the Andes or Himilayas, the best choice is .043 mains & number 69 powervalves. Set it and forget it.
No Strombergs were killed or injured during this post. . ." :-)"
 
chap52 said:
When we were teenage know-it-all wanna be mechanics we would spray water from the garden hose into a hot muffler through the tail pipe to destroy the contents. Cheaper than a new cherry bomb muffler.
Just don't rev the car up to blow it out while it is in you dads driveway About an hour for three knuckleheads with scrub brushes and a can of Comet cleanser to clean that mess up. LOL Chap
Click to expand...

Great idea! I may try this with my half-plugged up old Midas muffler. Another guy told me about firing a 22 caliber rifle into the tail pie to help open things up a bit. There's a whole menagerie of off-the-wall shade tree fixes that are actually effective for the desired outcome.
 
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