Like most of you, I pay very close attention to how my engine is running. How it sounds at idle, the power delivery during normal driving, and of course the way it pulls at WOT. Well, in the past couple months my 96’s engine just hasn’t seemed as smooth as it used to. A passenger probably wouldn’t notice what I am talking about; that’s how minute the problem was, or so I thought. I believe the severity of my problem was amplified by this 97 I am selling, which actually seems much quicker and smoother than my 96.

Last weekend I decided to check the bolts at the end of each header flange (where they meet the cross-under pipe). All 4 bolts were able to be turned 3 to 4 times (tighter). Next, I checked the center clamp (where the two halves of the cross-under pipe come together). Sure enough, those were loose too. The cat flange bolts/nuts? Loose. Even the two nuts holding in the 02 sensor were a little loose. After tightening all those nuts and bolts, the engine seemed to run a little smoother – at times. Strange I thought.

Ultimately, I had been avoiding the dreaded 3.4L Edelbrock header “nut from hell” on the driver’s side. This NFH is aptly named due to the Edelbrock engineer who decided to play a sick joke on the 3.4L enthusiast and route the driver’s side center header pipe (#4?) within 1mm of the exhaust stud. Good call genius. I kept reassuring myself the nuts were fine; otherwise the engine would sound like a lawnmower. I finally gave in and last night I decided to take my 14mm wrench and do some “nut checks.” I found 10 out of 12 nuts to be hand tight. And guess what? The NFH was barely finger tight! That explains the majority of the noise and why it was coming from that area I guess.

The moral to the story is to check the torque on your header nuts. Despite a proper install a few months ago (tighten, start it up, tighten, drive 100 miles, check) the nuts can obviously still work themselves loose. Symptoms of loose header nuts include: Slight loss of power, “choppy” power delivery, abnormal engine sounds, and a medium-pitched “valvey” sound while driving next to concrete barriers on freeway on ramps.

Make sure you know what you are doing before you go out and start wrenching. It is quite easy to break an exhaust stud off in the head if you are not careful.

 

Have you been using any kind of steel locknuts? (I'm not talking about nylock nuts). Downey has one type of steel locknut with their header stud kit.

 

I am using a nut with a split halfway through it. I think it is the stock nut.

 

Some of the lock nuts lose their locking ability after a few on and off cycles. Maybe some new locknuts would help.

 

Yeah, not a bad idea. If this keeps happening I might have to consider something like that. I wonder what would happen if I dropped a layer of thread-locker on the exposed threads. Or maybe a little bead of high-temp JB Weld that could be picked off if I needed to remove the nut.

 

Is there room enough on the bolts for another nut?
Since you've gone through the hassle of tightening them all...

 

Yeah, on some there is enough room. On others you have to the hands of a 2-year old.

 

there is penetrating thread locker for putting it on stuff thats already assembled so the parts dont back off of each other

 

Oh Gawd... you're making me check my nuts. sigh.


Is there a "high temp" version of JB Weld? I know that the stock stuff is only rated to 600*.

 

Maybe copper coat would work, it’s used as a header gasket adhesive/sealer.

 

I don't think so. I just looked on their site and I didn't see anything high-temp. I hate the NFH on the drivers side with a passion. For this and this alone, I do not recommend Edelbrock headers to anyone. I emailed them about their design flaws (many of them) and they did in fact respond. Of course the "technical" guy that responded claims they have never had any of the problems I described, but he said he would FW my concerns on to the engineers. yeah right.

I did weasel a set of gaskets out of them - or so they said. I have yet to see them and it has been 5 business days.

If I could do it all over agian, I would never have purchased headers. They are too much of a pain.

 

Try some Stage 8 locking header bolts. I had them on a 350 in my old Jeep and they worked like a champ. Put them on and don't mess with them till you take them off the next time and the are reuseable. Bryan

 

Wait until the S/C winds up with them.