Header Bolts

[81 Corvette]

Which are better, teh stage 8 locking bolts or the bolts with the allen head in the middle.

 

[Bob Chadwick]

I put the Stage 8 in earlier this year and have had no problem. I have read about the others but have no experience with them.

 

[Red69]

I tried the others but now have Stage 8 and like them, wish I tried them first. The trick is to torque the bolts down evenly, then fit the bolt locks againts your header tube. If done correctly, the bolts can't back out and maintain a good seal. BTW, the bolt head will accept an allen wrench for ease of installation. Don't think you will be disappointed.

 

[WayneLBurnham]

One thing - If you have the headers off and have a torch...

Do yourself an enormous favor and heat up the primaries on the ones that are close to the bolts and squeeze them in a bit with a pair of giant channel locks.

You don't have to pinch them much (nor are you easily likely too!) to make header bolt installation "easy as upside down cake". I had a beast of a time putting the Stage 8's on the last SBC I used with these same model headers - only 3-4 would even go in decently.

A few weeks ago I put the headers back on the 'vette and had thought to do this this time. I had ALL the bolts started in 10 mins on each side with no problem and could use a socket or a ratcheting box end on all but a few. (I used an allen wrench mounted on a socket to do the main driving, but these strip easily when torquing. I got all the Stage 8's to go to a place where I could put on the locks, and they are working great with no leaks behind the copper exhaust gaskets.

 

[The73vetteman]

Someone educate me here please - what are "Stage 8's"?

I inherited allen bolts on my headers and they seem to be frequently working loose, so maybe these "stage 8's" are the solution, if only I knew what they were!

'73

 

[WayneLBurnham]

Stage 8 bolts....

Stage 8 bolts are another answer to the perennial loosenning header bolt problem. They are a somewhat conventional high temperature SS reduced head bolt with an allen head center also. They are only about Grade 3 or so, like most such higher temp SS (can't use normal heat treating reliably on that application.)

Just like using conventional lock washers doesn't work very well because the heat detempers them and loses the spring tension, the worng cheap hardened SS or even some carbon steels will soften in such use.

To take another approach to bolts backing out, some use hardened studs of good quality (which are often easier to mount too...) They then use two nuts on each stud which they crush against each other once the inner one is tight (like you do with collector flanges.) Others drill the bolts or studs & nuts for safety wire or cotter pins to provide a different kind of mechanical securing against the rapidly changing thermal environment and vibration prone area which cause bolts to back out.

The folks at Stage 8 got real clever about five years back and made a D-shaped ring that has a hex cut out of it that you slip over the tightened bolt.
the cutout of the D will hit the pipe and prevent the bolt from unscrewing more than a fraction of a turn. The bolt is also slightly modified with a groove cut in it so you put an E clip on over the D ring - thus locking it in place.

All the big suppliers have them, from the vette special ones to JEGs, Summit, PAW, etc. Some have a nice large pic - might look at JEGS or SUmmit for such a thing.

They work very well, but sometimes it is difficult to get the bolt turned to the right place to get the D ring over the head of it - especially on aluminum heads without built in helicoils in the threads (easy to strip by overtightening). On my piece of garbage Blazer I couldn't lock a number of them without loosening the bolt too much - and it has iron heads.

I won't use anything else. I also prefer thick pure copper exhaust gaskets, although they make soft aluminum ones I've never tried and an old trick of using two asbestos/graphite/thin metal type gaskets, put on after soaking in water for a while, also works decently.

Supposedly a Stage 8 design for collector flanges is out, but I haven't seen it, so I just use the biggest bolt I can fit in with two fender washers and doubled nuts. (I also use pure copper collector gaskets.)

 

[Red69]

Wayne, thanks for the detailed description of the Stage 8 bolts. I'd like to add one suggestion to getting the D-shaped locks to fit. After torquing all the bolts properly, install the D-shaped locks. If one doesn't fit tightly against the header tube preventing counterclockwise rotation, don't back the bolt out; take the D-lock to the bench grinder and grind enough off so it fits tightly one counter clockwise rotation point on the bolt head. I needed to do this on 3 or 4 of mine insuring a proper fit and no chance of the bolt backing out. After checking that each D-lock is tight against a tube, install the C-clip retainer and all is well. I think the directions make some mention of this technique for obtaining a tight fit with the D-lock.

 

[WayneLBurnham]

Yep Red69, you're right....

Found the instructions and they also specifically mention it was OK to grind away a portion of the aluminum D Ring to make it fit. Remember you are grinding aluminum, so don't do it forever on the same grinding wheel without cleaning the aluminum build up off or you can overheat the wheel. (I stupidly blew up a fairly new 8" wheel on myself from grinding down less than 1/2" of a small aluminum bar - good deal they don't have a lot of inertia and I always wear goggles - still gave me a nice head ache, bloody nose and the grinder actually wobbled over and hit the floor...)

I heartily agree on not backing off the bolt to make it fit - it'll just make it leak. You can fairly safely tighten it somewhat more (only would need to be a fraction of a 60 degrees.) Just be careful of doing this with aluminum heads in the case your particular heads do not have built in strengthening helicoils to handle the slight overtorquing. (Edelbrocks do, so do AFR's I believe...) Of course it always helps to use a good antiseize compound or at least high temp grease or motor oil anytime you put bolts into aluminum, even for spark plugs.

 

[Red69]

This is what the Stage 8 bolts look like. They are available at Jeg's and most speed shops for around $40.
[font=helvetica,]Stage-8 Locking Header Bolts [/font]

View larger image
[font=helvetica,]Product images may differ from actual product appearance.[/font] [font=helvetica,]Made in the USA, Stage-8 Locking header bolts are made of grade-8 quality steel and use a patented 3 piece system that consists of a grooved bolt, a retainer and spring clip. The retainer fits over the head of the bolt, the retainer fits up against the header, and the clip snaps into the groove for a secure fit that won't wiggle loose. Bolts feature a recessed allen head inside the hex head for instalation in those tight spots. [/font]