Exhaust: 63 Avanti Headers?

[Jaybot]

Where can I find headers for my 63 Avanti?

[Mike Van Veghten]

Tubular or cast iron ?

Mike

[Jaybot]

Tubular or cast iron ?

Mike

Looking to add more power so tubular?

[PackardV8]

There aren't any commercially available tube headers. FWIW, even though I pointed out the downsides, a while back an owner just had to have headers. They cost more than $750 to make, coat and install and didn't add any significant horsepower through the mufflers. They did noticeably increase the noise and heat levels in the cockpit. The owner was also disappointed they didn't show up better with the hood open. He wanted them for bling, but they're pretty much buried down there.

Same with the reproduction iron R3 manifolds. They don't add much horsepower through the mufflers and they're heavier as well.

With mufflers removed on the strip or at Bonneville and above 4,000 RPMs, then headers make a lot more horsepower. Then with open headers, the carburetor has to be rejetted to match the better breathing.

Your opinions and results may vary.

jack vines

[Mike Van Veghten]

I "sorta" agree with Jack..

The iron copies or tubing headers CAN add power, BUT...you need everything else to go with them.
One thing I've found out porting Stude heads, R3 manifolds, and various intake manifolds and testing most of what I've done on a flow bench......is that the Stude engineers did a pretty good job of "matching" the capibilitys of their engine parts. Except maybe the compression ratio..!
If you have a higher thAn normal blower pressure...then, it'd be a toss-up I think...then I think a set of R3 headers would help, again...with the proper setup.

From the intake manifold to the exit of the exhaust manifolds...OEM parts flows, are very close.

Now to the purpose of installing headers. Getting the burn't gasses out and "helping to pull" a fresh new charge of fuel in. This takes a fairly carefully designed set of tubes to do this.
And as Jack notes, because of the original designers, designs, using all or mostly all stock parts, headers, even carefully designed on a stock engine, won't gain much if anything.
Actually...this pretty much includes the big three also..!

BUT..you add a roller (or other high lift/duration cam) cam, a high flow intake, a big carburetor, lotsa compression, then yes, (despite some), a set of well designed headers will help power output.

I have an engine I've got to finish...roller cam, very heavilly ported heads, a VERY rare, high flow intake manifold, sorta high compression ratio (for the street), big carburetor,..yes, I've got a set of R3 manifolds that will get replaced by a set of headers after everything is sorted out.

Something is seems many people don't realize, that any free'er flowing exhaust system, "needs/requires" the intake to be retuned also..! Unless the engine is running rich to begin with, an otherwise properly running engine, will need to be richened and quite probably a coupla degrees more ignition timing...all to make the header investment worthwile...power wise.

As for headers with mufflers....in my opinion....yes, as noted above, if everything is well above stock form, and the system down-flow of the headers is also well upgraded (2-1/4" or maybe 2-1/2" tubing and mufflers), headers can be a benefit.
A stock or 2" exhaust outlet with a mostly stock engine...not so much.

Mike

[Jaybot]

Let me rephrase the question... I have already upgraded to larger 2 1/4 exhaust and will be porting the heads by a well known Stude mechanic very soon. So then it will add some more power according to what I have been told. or not?

[Mike Van Veghten]

Without trying to sound ugly, (!?), depending on who the "well known Stude mechanic" is and what he's going to do (there are MANY things to do and not to do to a Stude head..!), and you still have a stock cam and I assume intake manifold..correct ?
Maybe an R2+ cam and more compression (noted earlier!) is in the works..?
Yea, you could gain a couple'a horse power from 3000rpm and up, mostly depending on the head work and cam and compression..

Is it worth the $750 to $1000 for custom headers...."only you" can answer that.

As another here says...your money, your car. You have to live with it.

I see this thread going the way of..."my 600cfm carburetor runs really great on my stock 259". Well, maybe it does, and many profess to this. That's not to say a 500cfm carb. wouldn't work....better.

Mike

[PackardV8]

Let me rephrase the question... I have already upgraded to larger 2 1/4 exhaust and will be porting the heads by a well known Stude mechanic very soon. So then it will add some more power according to what I have been told. or not?

More detail always begets a better answer. So, short answer is yes, headers will add some more power.

If this were a BrandX where headers are a $250-350 part, we wouldn't even be having the discussion. However, as Mike said, headers will have to be custom built at considerable expense. Even the R3 exhaust manifolds seem to be currently out of stock.

Without more details as to the extent of the head porting it's difficult to know; has the intake side been completely upgraded? ST5 cam or better, R3 intake valves and springs, high flow intake manifold? Until those are done, custom headers won't make a great improvement for the cost involved.

If you do custom headers, have them ceramic coated inside and outside. The Avanti cockpit already runs hot with the OEM exhaust. Headers shed noticeably more heat. and noise.

jack vines