Just a tip that worked for me:

I tightened the headers on my truck when I installed them cold, I then warmed up the engine and tightened them hot, the bolts never came loose after that.

 

I have heard that and honestly have never tried it. Makes perfect sense to me. Almost tempts me to try headers on my 460. Why are we such gluttons for punishment?

 

I'm trying to figure out how flow restriction gets you more low end torque.

 

Marc I just read an article about it.. it stated that the shockwave from the exhaust valve opening rebounds back in a manifold and causes about a 10% increase in Compression, which is what causes the Low end torque increase! Also that smaller diameter headers have a similar effect, but to a lesser degree. The smaller diameter headers cause the exhaust flow to be faster then larger diameter pipes which aids in exhaust gas scavenging, at lower RPM,, but with more restriction then large Diameter pipes at High RPM.....So if you are looking for torque manifolds and Small Primary headers are a better choice.. but if you are looking for big HP numbers at Higher RPM Big Pipes are your choice!

 

When I did my engine rebuild/ hop up I went with Aluminized Ceramic Coated headers.. the cost difference between them and painted was $100 which is about the same price as 2 rolls of Header wrap... and it looks a hell of a lot cleaner... it also contains the temp internally like wrapping does.. but is a lot less headache to keep looking nice..and it will never rust. They look like polished aluminum and once every few months I clean them with Windex per the manufacturer's suggestion.. I used a block hugger style, short tube which give the advantages of the Manifold, for torque, but with a larger Diameter I also get tremendous top end I have this on an FE which is bored over displacing 361 cu.in. With a mild comp cam, and ported and polished heads I get 348 hp at the crank... and in this configuration with a t98 to a Dana 60 with 4:10 gears, I have been getting 16 MPG around town and 20 MPG highway.. all while hauling about 800lbs of tools in the bed of my 64 F250..... It is a matter of deciding what your goal is for your truck, and then figuring a way to make it work...

 

Well I'll be dipped........
I might have to drink a little on that one tonight.

 

Why is this even a question? The only reason i'd ever stay with manifolds is if i had something and wanted everything completely original. If not, then it's headers, PERIOD. spend the money.

 

Dunno man....I have no idea. Headers are a no-brainer (no offense to anyone) in terms of overall performance.... and headers don't result in this:



'musta been all the back pressure that blew out the cast iron .

 

or all of that raw power comin out of each cylinder!

 

Agreed
But the question was, does a certain amount of back pressure increase low end torque.
If it's my truck it's getting headers.
Ahh, but what size grasshopper?

 

The truth about exhaust backpressure and torque

 

After reading a few of the replies in this thread i was darn near ready to yank the headers right off my FE and replace them with the old cast iron "logs".


Backpressure: friend or foe?
http://www.veryuseful.com/mustang/te...Scavenging.pdf

 

Below are a few of articles for your perusal.

Engine Builds
Ford 406 Engine Build - Hot Rod Magazine

How We Got Over 500hp from Ford's 400M Engine - Hot Rod Magazine

Header Basics: Header Basics - How Headers Contribute to Horsepower - Car Craft Magazine

A more in depth discussion on primary and collector sizing:
1

 

Lot's of different opinions, so I guess it comes down to personal preference

 

I have a set of headers to fit my 74 390, they're still in the box, and may stay there for quite some time. I only bought them due to getting the new-in-box headers and an Edelbrock Performer 390 for $120 as a package deal.
If I do get around to installing them, I'll likely test fit, then get ceramic coated after modifying the collectors. I hate the flimsy 3 bolt flange setup.......
On the other hand, I do have a header on both my Mazda RX7 and the B2300. The B2300 came factory (tubular exhaust manifold). The RX7 header is a bit overbuilt. 7/16" flanges and 1/8" wall pipe mandrel bends PLUS ceramic coated. No wonder a 2 pipe header costs $250......... If someone built headers like that for a 390, they would cost $1000, but be worth every penny. Especially if they fit as well as the one for the RX7.....