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Hi All,
I will be having a set of new pipes bent for the 1949 Convertible next week. I have a set of NOS hangers and a set of NORS clamps. Odd thing, the front clamp is for a smaller pipe that the rear. The boxes show front and read and the MOPAR part numbers are on the boxes for X-ref.
If this is in fact correct, then I am assuming that Desoto used a 1-3/4 inch header pipe and a 2 inch tail pipe. Did they want to push down the RPM curve the torque? That is the only reason I can figure to do that.
Does anyone have any documentation on the pipe sizes for 1949?
Thanks, James
I do not have the answer but I know I have seen what I call a bend sheet I will see if I can find it online again and check if it has the pipe sizes.
Darin
It turns out that on the boxes of the clamps, they list the MOPAR part numbers they are replacements for.
The front clamp is a 1064458. This clamp is the smaller one and is 1-3/4 inch.
The Rear clamp is a 1064459. This clamp is the larger one and is 2" inch.
It looks like MOPAR made the header pipe smaller than the tail pipe. Do doubt to push down the torque curve.
There is a NOS muffler on ebay from the period and the posting says that one side in 1-3/4 inch and the other is 2 inch.
So, unless I find some evidence to the contrary, I have to assume that the proper exhaust for a flathead six is 1-3/4 inch from the manifold to the muffler and 2 inch from the muffler to the back of the car.
James
James
With all engines the heat of The Exhaust Gas Molicules are "large" when
hot and get "smaller" as they cool. This is why the pipe is at a larger
diameter from The Exhaust Manifold to The Muffler ( most of the time ).
After The Molicule Flow leaves The Muffler every thing is cooler and smaller
so the larger diameter of the piping is not needed.
To have a larger diameter after The Muffler is OK if you plan on being a
contender with NASCAR or have power dreams because "you heard or
read sumthin on the inter-net.
With your exhaust do take note the end of The Exhaust Manifold is a
slightly in-larged diameter so the tip of The Exhaust Pipe can fit into it.
( My 1956 Engine is even the same way. )
When I last needed mufflers the local NAPA had them ( they matched
the measurements to what they have in their Muffler Books ).
I hope I said all of this correctly.
Rodger & Gabby
COS
FltSgt@outlook.com
Roger,
I do understand that issue. However, it is evident from the documentation that they used a smaller header pipe than the tail pipe. The size of the header pipe directly affects the torque curve. A smaller pipe causes the stock engine to produce more torque sooner, although at the expense of less peak horsepower at the upper RPM ranges.
I am assuming that is why Desoto used a 1-3/4 inch header pipe. They no doubt did dyno testing and figured out that that is the best match to the stock head and stock manifold for getting the power curve they wanted.
I also have found out the length of the pipe for the convertible which is just as important to the torque curve as diameter. In my case, I want a longer pipe to the muffler so that there is more torque below the peak torque point. That will help the old six move out from a stop sign in todays traffic.
Best, James
