Best headers for 360 in a valiant
I’m going to make a post there in a bit, very heavy thunderstorms going on right now so can’t get out there.
Is there anything you can do to limit the power loss or is the pipe just too small?
The header pipe diameter should be sized to the amount of exhaust the port can pump out. A next size in diameter normally doesn’t hurt though you could, combo dependent, loose a little bottom end torque.
The length of header pipe will broaden or shorten low end torque. The shorter the head tubes, the less torque the engine makes. There is also a point of to long of an exhaust tube pipe, which you don’t have to worry about since there are only a very few headers on the market that exceed this general length. The big block fender well headers come to mind. Even more so when used without a collector extension.
Much of this is a build dependent issue.
For a general purpose header, a 1-5/8 will take far of most street engines.
A 1-3/4 will work very well with ported heads and camshafts on the larger side of what a general sized camshaft would use in a street engine.
If this seems a bit broad, it is because there is a huge great area in it’s application as well as a complete lack of your engines information.
I’ll give you my current examples. Both headers are currently wrong on the cars for there application. So, IMO, this is what not to do. The. I’ll tell you why I did it.
Example #1;
1979 Dodge Magnum, 5.9 Magnum short block dead stock. Added components are a Edel. Air gap, 750 cfm AFB, chrome box ignition, Hooker Super Competition headers @ 1-3/4 into a 2-1/2 exhaust.
The stock magnum heads exhaust is better than the LA head but falls short of any decent flow cfm. The pipe is to large and causes a little low end torque loose. This is lightly noticed but has been proven in tests before.
Why do I use this header? Ground clearance! This header is for B and E bodies and is shaped very different than the standard headers. They are closer to a TTI header in looks.
This header is in use with future upgraded camshaft and cylinder head plans. The off idle to 2200 power is ignored with the larger camshaft as well as supporting stall converter, tires and gears.
Then it’s a better package all around.
But as is now, a 1-5/8 would be it.
Example #2;
‘71 Duster, 340, 10.5-1 ratio, CNC aluminum heads, 241/@050 intake camshaft, 3500 stall, 750 carb, 4.88 gears, etc… Headers are 1-5/8.
The header size for this is a bit small, it’s not the end of the world. However a 1-3/4 would be better for the upgraded exhaust port to get the gasses out. With lower focused above 3500, a small tube header is not needed or warranted. In fact, it’s robbing upper power potential.
While the car is also being lightened, its future engine will see the a small solid flat tappet @ 260@050. This would be large for the street. (As well as the current converter being wrong)
Why, it’s temporary. These are my test stand break in headers for new engines. They will be returned to the engine break in stand shortly.
I’m planning on a 4.0 arm stroker. 416+ cubes. This will see a minimum cam mentioned above. The header size will be a more appropriate 1-7/8 tube size with a minimum 3 inch exhaust.
This is a more of a drag motor with minimal street use.