Header tube length

[std]

How important do you think equal length tubes are.

The reason I ask is that I built a motor that I thought would pull pretty good up to 7000rpm. The owner got a set of headers made. The tubes go straight from the port to the collector. As you can imagine, the lengths are not even close.

The motor runs good in 1st but falls off at the top of 2nd and 3rd. I've seen similar cam/head combo work well.

Do you think I need to rework the headers or look in other areas?

[shaun callaway]

Re: Header tube length

my opinion would be to rework the headers first then look in other areas.

[Dynoroom]

Re: Header tube length

It's not the headers.
Look at the basics, fuel delivery, etc.
Give us more details on how it's running.

[squirrel]

Re: Header tube length

The music analogy will be sure to confuse people! but the rest of it sounds reasonable

[RacerRick]

Re: Header tube length

If it runs hard in 1st, then fall flat in later gears, its definately not the headers. I would be looking at fuel delivery. Might be emptying the fuel bowls.

Equal length headers are only worth a few HP in 99% of situations.

[JeffMcKC]

Re: Header tube length

I agree the headers are not it.

The gear multiplication maybe helping cover up problems in second and third. High gear is where you find out if your making any onions or not.

[std]

Re: Header tube length

The other problem I should have mentioned is the top of the air filter is at most 1'' from the top of the carb. It has one of those K&N filter tops but the hood sits right on the top. It doesn't seem like a good thing so we're going to modify the hood to get more clearance.

Unfortunately winter is about here so I can't much til spring. I'm just trying to get ahead of things, trying to think of what we should do.

[JeffMcKC]

Re: Header tube length

The K&N fitler top is ok on a FI motor but not on a Holley, they do not like air coming in from the top it will take about 25 HP from it at a High RPM

[blu65ramb]

Re: Header tube length

Jeff, thanks for that, i was going to try that on my holley carbed 406

[Eric68]

Re: Header tube length

I agree with the others that the headers are not the problem in this case, but wanted to tell you that for best performance having the correct tube length (not necessarily all equal) and proper tube diameter is key. Same with collector, you need the right diameter and the right length.

I built a set of "equal length" headers for my car last winter and got them within about 4" from longest to shortest -- the average length is the correct length for my combo.

[KeithTurk]

Re: Header tube length

Funny how most of us that have actually tried some silly stuff with Headers know the same thing...

Equal length... Tube size and so on... is often on the wrong side of the decimal point... while it's better to be "right" it simply doesn't hurt as much as you might think to be wrong...

Freiburger made 1013hp to the rear wheels through a set of 1 7/8" tubes... that were basically junk...

K

[DanStokes]

Re: Header tube length

And the tubes on Dave Maty's Top Speed Shootout winner were cobbled together. I know - I was there. But they sure seemed to work just fine. I'm hoping to build an equivalent set for my Six from a set of Cliffords designed for a pickup.

I guess we'll see if they are better than a stock integral head (hard to be worse!)

Dan

[72_Ventura]

Re: Header tube length

std-
What transmission is the car running? It sounds a little like it could be a TV cable issue in a 700-r4 or 200-r4 set-up. The fall off could be caused by late shift points. If you are running something with a TV cable (not the same as a kick-down) I'd mess with that some.
Just a thought...

[TC]

Re: Header tube length

I'm calling fuel as the problem. What fuel pump is he running and what does he have the pressure set at. Also what size/make motor are we talking about.

[JeffMcKC]

Re: Header tube length

I would say we need a lot more info to tell where the problem is, at this point its all just keyboard geussing.

Come on, give it up what, you got. LOL CID,CAM Spec, give us a list, I am sure we all would like to give our opinons.