W-body + S&S headers = Noise?

[PCGUY112887]

I know the headers are super close to the firewall, actually touching it in places (touching where the heat "fabric" of the firewall is).

I thought they may make a bit of noise going into reverse, and be quiet the rest of the time (since that is when the headers would be pulled "up" a bit, hitting the firewall).

Well it seems to be the exact opposite. Going into reverse is smooth, but going into drive there is a bit of a "clunk". Then while driving, anywhere between 1700 - 2400 RPM's you can sometimes hear them, sounds like they are vibrating against the firewall or something. Usually I can only hear them while coasting down, or at light acceleration, any other time I can not hear them.

Have any of you experienced this? If so, where were they vibrating at? I will put some header wrap to soften it wherever they are hitting, but I can't see or tell where.

Any other input? Thanks.

[whitelightnin04MC]

Here's my clearance on a 2nd gen w-body. I know it isn't the same at all, but I think some of the 1st and 1.5 gen w-body people modify the firewall with a plasma cutter. I seem to recall that they were cutting out a square and adding a piece of metal and reattaching it to get more room.

[JMo60]

I have a 94 Grand Prix, and mine did the same thing whith stock dogbone motor mounts. i made some urethane mounts and that holds the engine from rocking, keepin the headers off the firewall. The SS headers fit my car nicely, very snug, but did not have to modify anything, then dropped in with the right persuasion

[PCGUY112887]

Mine seems to be the opposite... my headers vibrate on the firewall till about 2500ish RPM's where I guess they rock "back/down" far enough to not vibrate.

It must be very slightly hitting from the way it sounds and chances with RPM. It's like all you can hear is the engine/exhaust inside the car till over 2500 then it goes silent and all you hear is exhaust behind the car.

[torq455]

pound the piss out of the firewall with a big hammer. that'll fix anything. :P

[PCGUY112887]

Well my headers no longer hit. Had my mechanic take a look at it (because he has a lift!) and we put washers under the bushings on the K frame to lower it a bit, hit the piss out of the firewall, and put some header wrap on areas that may hit. Only a bit of noise when in reverse, but nothing going into D or while driving!

Also got my SS brake lines on (had to chop the lines, mechanic couldn't even get the fittings off).

Tune next!

[IsaacHayes]

Must be nice to have a mechanic with a lift...

http://60degreev6.com/showpost.php?p=335736&postcount=13

Looks like poly might be pretty easy to put in there already made... check it out.