problem with gibson headers

[eran tomer]

Bought those expensive headers and found that the through holes are too big for the bolts, which means you can wiggle the header around and never get the exact mounting spot. Any one had this problem with headers?

 

[Schurkey]

Use the header gasket to transfer the port shape to the header flange.

The oversize holes work to your advantage.

 

[eran tomer]

The oversize holes work to your advantage.

Why is that?

 

[GoToGuy]

How much bigger? Are you not able to hold the header centered while torquing the bolts or studs down? There are tapered cone shaped washers available. Have you contacted Gibson, what's their response?

 

[eran tomer]

How much bigger? Are you not able to hold the header centered while torquing the bolts or studs down? There are tapered cone shaped washers available. Have you contacted Gibson, what's their response?

1.1mm diameter holes vs 0.9mm diameter nuts. I haven't tried to mount them yet but to my judgement it's enough for the header not to sit exactly where it's suppose to. The OEM manifold have the 2 center holes exactly the size of the bolts.
I'm waiting to Gibson's response.

 

[Komet]

Buddy, headers are a custom fit job. If you want direct fit replacements, buy stock parts.

 

[GoToGuy]

I bought my ceramic coated headers and unless they did not fit or holes misaligned, I set the carbon fiber gasket in place then centered manifold while torquing the locknuts.
Is 3/64 " or 1.1 mm an excessive tolerance? If it was for a Gulfstream G4, we might have to make a call or two.
Gibson's thinking could be providing for variances over wide year range.
The clamping force of the nuts is the retaining force. And as long as the outlets line up your good.
If the contact area of the nuts base to flange is a issue, some SAE or similar metric stainless washers to spread clamping load of the nuts.
My personal choice is anti seize and high temp locknuts.

Good luck!

 

[eran tomer]

Buddy, headers are a custom fit job. If you want direct fit replacements, buy stock parts.

if you talk about the alternator bracket then yes. but not the mounting bolts.
You put one header 1 mm forward and upward and the other 1 mm backwards and downwards and you can't fit the y-pipe.

I ended up going to the machinist to make some spacers to eliminate this play.

 

[GoToGuy]

Why couldn't you just fit the headers in place. Then tweak, massage , work the exhaust tube flange to fit the new position of the header flange.

 

[Supercharged111]

Just a guess: the header port is larger enough than the exhaust port that this is a non-issue.