Stock Manifolds or Headers?

[BlitzK5]

My manifold bolts have rusted in and broke so I got bad exhaust leaks around the connecting flange. Should I even bother and drill them out and re tap them or should upgrade to a set of headers for my 454, or is there not much of a performance gain from going fom stock manifold to headers. What are the advantages and disadvantages. And since its a 454 and Im running 38's do I need to even bother with headers since the 454 should have more then enough power and torque. I am also going to be installing 4:56 or 4:88's

 

[diesel4me]

Catch 22....

Its a toss up--keep the OEM iron manifolds,and you always have to deal with "donut" gaskets leaking (if they use one--some styles dont and use a metal flare instead)..and the studs always whittle away and break..sometimes they can crack...

Headers will give a power boost,but they seem to leak all the time where they meet the heads,only expensive copper gaskets seem to work the longest without blowing out or leaking--they leak like sieves a the collectors most of the time too,and they often hit the spring shackles or other places a lot of the time..and you need a "custom' exhaust to fit them..Oh yeah--if you live in the "rust belt",they rot out in a few years too..

I tend to stick with cast iron manifolds--I hate nothing more than that annoying "fftt--fft'fft'' of a leaking header,it sounds like a bad lifter!--and my "smog inspector's"eyes doesn't go like this when I open the hood at inspection sticker time.. ..

The best of both worlds is factory tubular manifolds,but they are hard to get and costly,and might not fit/work on all years and models..at least they pass a "visual" inspection with no hassles...

 

[chevyracing]

You will have a minimal increase in power from adding headers that you won't notice on the pedal. Headers have more upkeep. I guess it depends on what else you have done to your engine and how well your exhaust flows now.

 

[BlitzK5]

The engine is manily stock with a Edlebrock card and intake manifold.

 

[rcurrier44]

Headers only realy help you if you have a hot running motor that the origional manifolds are holding you back. The ones that I have have been such a pain that I am switching back to stock manifolds.

 

[divorced]

I always had headers on my older trucks and haven't had any problems. I use exhaust manifold gaskets instead of header gaskets and they don't leak. I also have the exhaust shop cut the collector off and weld the exhaust pipe to the header = no leaks and no header/shackle clearance problems. The exhaust is fully welded from front to rear.

If I ever use manifolds, I don't use any gaskets with them; just bolt them directly to the head.

 

[Russell]

Newer EFI manifolds SUCK. Every time I take one off, I gotta use a spreader to get them back onto the engine, which is a huge pain in the butt.

I've got headers on my K25, and they don't leak at all. Key is to cut the little bar that goes between the pipes where the header bolts to the head, and to grind that lip off the collectors so the gaskets are squished by the entire collector rather than the just that little lip. For gaskets, I use two copper gaskets on the bottom, and stock style manifold gaskets on the heads.

Cutting those flanges allows the pipes to bend freely from eachother, which makes a huge difference.

Also, if you keep your headers clean, they won't rot so fast. I wash my truck weekly during the winter, and at least twice a week during the fall and spring when there is lots of salty slush on the road, and I make sure to wash my headers every time I wash the truck. Going on 2 years with those headers, and they look the same as the day I put them on there -- surface rusted but not pitted.

The biggest problem with headers is how loud they are. I personally don't like a truck that is so loud it wakes the neighbours 5 miles away up when I start it in the morning, which is how my GMC is.

I'm planning on going to a set of EFI manifolds (yeah, I know, I said they suck, but its tough putting an 02 sensor into a non-efi manifold) and a set of Aerochamber mufflers. Should be much nicer than the flo-pros I've got now (plus, I have kids literally fighting over who gets to buy it from me when I put the manifolds / quieter mufflers on, lol)