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Hooker Headers - small primary tubes
#1
Hi guys,

my buddy and I were installing the Summit exhaust system SUM-680111 and the hooker headers HOK-6915HKR. The result is awesome in sound and agility, my mustang is now another car, a torque- and drive-monster Big Grin

BUT: why are the primary tube ports on the headers so small?!? And they have ugly welded seams which are in the size of the smaller 2V head's exhaust ports:

[Image: 20140222_173022wzr6v.jpg]

[Image: 20140222_1730371rq27.jpg]

But I have the 4V heads (1971's) with the big ports and they would have been covered by the gasket only a little with a lot of blow by. Why is this manufactured as it is? There are so many hooker jusers out there - nobody gets to this point before? I get the "right" ones from summit for 4V heads 71-73...

So we decided yesterday to flatten the whole flange and made the edges a lot smoother and then had to weld the seams as a result of this - it was a PITA work ... Dodgy
It is now a little bit better fitting to my large exhaust ports but not exactly what we want.

[Image: 20140222_173052lgp0h.jpg]

Is this by purpose from the manufacturer?

What do you think about it? Keeping in mind different stances concerning torque etc. ...

The rest of the exhaust system also needs a bit of tweaking because of my staggered shocks but the result is fantastic Big Grin

[Image: 20140223_01195859rr9.jpg]

16 hours of work at a time - my knees singing a song of it today...


Tim

Tim

Never drive faster than your guardian angel can fly Angel
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#2
the Hooker site says the 6915HKR headers are Comp headers, not Super Comps. Hooker sells up to 3" primary tubes for your heads. The smaller tubes provide more back pressure which increases torque, at the expense of high rpm HP. If yo are driving 100% on the street you would most likely be happier with the headers you have. If you will be running 7000rpm on the Autobahn for hours at a time you probably want the bigger tubes. And the material you ground off is described by Hooker as the "welded O-ring seal"..." to ensure a perfect sealing surface." I dont use gaskets on my exhaust manifolds.
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#3
tests I have seen have shown very little difference in minor changes in primary tube size. Switching from 1 5/8 to 1 3/4 had no effect on a smaller V8 (360-400 CID) The general rule is exhaust pipes can never be "too big", but don't sweat it.

What's the DCR, compression, and displacement? Those factors along with cam specs could help, but really, don't sweat it for a second. Those will do fine.
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#4
@wwhite72 and jsup:

Thank you for both replies! So with your words and my feel I am coming to the conclusion that it is good as it is. I enjoy the power at low rpm but also the ease of the engine lusting for higher rpm with that setup. And I will never driving at high rpm for hours. I only was first "shocked" by the small tube-entries of the headers. It felt like they would block the exhaust flow more than power it up... And I am feeling better to have a flat flange surface with gaskets on them Wink

Tim

Tim

Never drive faster than your guardian angel can fly Angel
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