Backfiring going down hill

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Dennis K Anderson
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Backfiring going down hill

Post by Dennis K Anderson » Mon Sep 27, 2021 8:19 pm

What makes a model t engine backfire going down hill. The throttle is all the way up. Is it carburetor or timing?
Dennis K Anderson
Maryville Tn


Scott_Conger
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Re: Backfiring going down hill

Post by Scott_Conger » Mon Sep 27, 2021 9:07 pm

Running very lean under those conditions. My Austin Healey would do that too, when downshifting. Never done that in the T.
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves
Obsolete carburetor parts manufactured


Don D
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Re: Backfiring going down hill

Post by Don D » Mon Sep 27, 2021 9:20 pm

Dennis,

I am not a mechanic just a parts changer. :-) If you are referring to that beautiful Postal Truck you built I think the issue may be a loose nut behind the wheel buddy. Seroiusly, call me, I have a spare rebuilt carb you can borrow to see if yours needs to be rebuilt.

May best to Ms. Connie,

Dom
Last edited by Don D on Tue Sep 28, 2021 12:16 am, edited 1 time in total.


Norman Kling
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Re: Backfiring going down hill

Post by Norman Kling » Mon Sep 27, 2021 9:21 pm

If the spark is retarded going downhill, the spark will come late, causing some of the fuel to ignite in the manifold or muffler.
Norm

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Bill Robinson
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Re: Backfiring going down hill

Post by Bill Robinson » Mon Sep 27, 2021 9:24 pm

Dennis- I'll bet that you are not running a standard Model T muffler. I'm running a muffler for an 8N tractor on most of my T's and they all backfire going downhill, but only if the timing is retarded. They are tough mufflers- much tougher than the Ford take-apart mufflers that are destroyed by a backfire.
When my granddaughter was young we'd be on a tour and I'd make the car backfire and she be in the back seat yelling "do it again, Poppy!" :D
Cows on the roadside hate it. :lol:


Jerry VanOoteghem
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Re: Backfiring going down hill

Post by Jerry VanOoteghem » Mon Sep 27, 2021 11:17 pm

Describe what you mean by "backfire". Do you mean explosions in the muffler, or "popping back" out of the carburetor? Each has a different cause.


Topic author
Dennis K Anderson
Posts: 10
Joined: Wed Jan 09, 2019 3:53 am
First Name: Dennis K
Last Name: Anderson
* REQUIRED* Type and Year of Model Ts owned: 1927 Mail truck
Location: Maryville TN
MTFCA Number: 50262
MTFCI Number: 23263
Board Member Since: 2010

Re: Backfiring going down hill

Post by Dennis K Anderson » Tue Sep 28, 2021 5:22 am

The backfiring is in the muffler. I am running one of those stainless steel mufflers. I don't think it will burst apart, but popping like that can't be too safe. Your commits are helpful and I will continue to chase this problem. Dom, I have been looking for that loose nut behind the wheel for a long time. Can't seem to find it. Thanks.
Dennis K Anderson
Maryville Tn

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Charlie B in N.J.
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Re: Backfiring going down hill

Post by Charlie B in N.J. » Tue Sep 28, 2021 6:50 am

What Mr. Kling said.
Forget everything you thought you knew.

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