Exhaust Headers

[ThickCobra]

Looking for advice. I have attached the exhaust headers (supplied with the complete kit) to my 351w and appreciate they need to be torqued and thread lock applied. However, I thought I might just tighten them temporarily and get several hours of run time on it. Then, remove one bolt at a time, apply thread lock and then torque to spec.

Sound like a good approach?

[Bob Cowan]

You won't be able to remove one bolt at a time. Just like installation, you'll need to pull the flange away from the head to R&R the bolts on the inside of the curve. Put a little bit of high temp silicone on the threads, then torque to spec. That seems to hold the bolts in really well for me. BTW, I don't use gaskets any more, only silicone.

[Bobby Doug]

Stage 8 locking header bolts. Once and done. After several heat cycles still tight. X2 on the silicone
Doug

[ThickCobra]

You won't be able to remove one bolt at a time. Just like installation, you'll need to pull the flange away from the head to R&R the bolts on the inside of the curve. Put a little bit of high temp silicone on the threads, then torque to spec. That seems to hold the bolts in really well for me. BTW, I don't use gaskets any more, only silicone.

Would the GE silicone II, same used for securing the aluminum panels work?

[Jeff Kleiner]

Would the GE silicone II, same used for securing the aluminum panels work?

No. Use Permatex Ultra Copper.

Jeff

[ThickCobra]

No. Use Permatex Ultra Copper.

Jeff

Thanks Jeff. I'll look for the Permatex Ultra Copper tomorrow. And, Doug, your stage 8 bolts reference had me google sources when I discovered that 3/8" hex heads are easier to access with a wrench, and more importantly a torque wrench. I was having one hell of a time tightening the 7/16 hex head bolts provided with the FFR headers. And, what might the torque spec for the bolts be?

[Bobby Doug]

I believe it would depend on who made your heads and whether they are iron or aluminum. I remember looking it up but it has been too many days since to remember the exact figure.
Doug

[Bob Cowan]

Don't worry about a torque wrench. You'll never be able to get an accurate reading on many of them. Just use your best judgement.

I prefer the 3/8" 6 point heads. The smaller head is easier to work with. And 6 point bolts can be turned with an open end wrench.

I initially used the Stage 8 bolts. That turned out to be a PITA after a few R&R's, and they got dumped. Standard header bolts with silicone is all it needs. I'v never had one come loose yet.

[CraigS]

Also a lot of use use the ultra copper instead of a gasket. You need to make sure the header flange is flat which I do w/ a big file so it's easy to see the low spots.

[ThickCobra]

Also a lot of use use the ultra copper instead of a gasket. You need to make sure the header flange is flat which I do w/ a big file so it's easy to see the low spots.

And the general consensus on stage 8 bolts with or without locking fasteners? And, red or blue lock tight on the threads, if any?

[Wjhutchings]

Am I the only one that uses safety wire on the exhaust bolts?

[Gumball]

.... and, make it a regular habit of checking to make sure that they are tight, especially over the first few hundred miles.

[ThickCobra]

.... and, make it a regular habit of checking to make sure that they are tight, especially over the first few hundred miles.

Good idea. And, it makes one wonder whether one should prepare and perform a pre-flight check list each time we take our cars out. Just kidding.

Chris, thought you might appreciate my attempt at wit.

Jay

[Chuck Sloggett]

I used Percy's locking header bolts, they have a 12 point 3/8's head and a allen head lock screw in the center. Never had one come loose. -- Chuck

[ThickCobra]

I used Percy's locking header bolts, they have a 12 point 3/8's head and a allen head lock screw in the center. Never had one come loose. -- Chuck

Would you also use some type of thread lock?

[GSides9]

Do you have aluminum heads? Thread lock can pull the threads out when you want to remove those bolts. How can you re-torque the bolts if they are thread locked? Mine are safety wired and tightened with an open end wrench because nothing else would fit.

Glen

[Chuck Sloggett]

Would you also use some type of thread lock?

The bolts are stainless steel and I have aluminum heads so I used anti-seize on the bolts. Dissimilar metal is almost always an issue and I would not use thread locker in this situation. Same with spark plugs in aluminum heads, use anti-seize there too.
The way the Percy's work is a mechanical bond by forcing the split bolts our against the heads. They are easier to install than the stage 8 type.
Another thing they are available in 3/4" and 1" lengths, if you have room I recommend the 1". In my AFR heads I chased the threads with a bottoming tap to make sure the bolts did not bind in the bottom of the hole. -- Chuck

[ThickCobra]

To summarize, Permatex Ultra Copper sealant, Percy (or comparable) 3/8" header bolts and anti-sieze on the threads. I also have aluminum heads and a 351w.

Thanks all.

[Jeff Kleiner]

On the roadsters I have built I've used Percy's gaskets at the heads along with either Stage 8 or Percy's Vibe-Lock header bolts (the Vibe-Locks are more user friendly). Before locking them down I run them through a few heat/cool cycles tightening as necessary after each. I use Ultra Copper at the header to sidepipe flange along with socket head bolts, lock washers and and deep brass nuts. Never a problem with this recipe.

Jeff

[AC Bill]

I used Remflex header gaskets, and would use them again.
You don't have to crank on the bolts to get a good seal. They work especially well with the Percy Split-lock bolts. Other than maybe an inch/lbs torque wrench, you can't use a very big wrench in that area, so you can't apply much torque on the header bolts. There are numerous threads of fellows having header flange exhaust leaks.

With the design of the Remflex gaskets, made specifically to be only partially compressed, you can snug up the tiny head on a Percy's bolt with a fairly small wrench, then lock it in, so it won't back off. The design of the gaskets also counters any unevenness in the flange surface.

[Jazzman]

While I am using a Coyote engine, I really appreciate your thread. It is quite helpful. In order to facilitate access to the rear most header bolt locations, I have decided to remove the rear most four studs on either side of the engine. I will replace them with grade 8 metric bolts. Today I purchased eight #10x1.25 thread pitch bolts. I took a header stud with me to Ace hardware. That is the size that seemed to fit. I have compared the bolts side by side with the studs. They look to be the same size. However, when I attempt to hand screw in the bolts in the holes vacated by the studs, the bolts quickly get too tight to turn by hand. I don't want to turn too hard for fear of damaging the threads in the block. Do I have the right size bolts? Is the reason that the bolts get tight the fact that there is still some left over Loctite in the holes that was on the stud for installation from the factory?

Thanks!

[AC Bill]

Did you get this figured out already?

I would definitely not put to much pressure into threading them in, if they seem at all resistant. Left over locktite could be the issue, but perhaps the thread pitch is off, even though they look the same. You sure don't want to strip the head threads..

I have run into that before. Metric sizing can also be part of the fun, you sure the original bolts are metric?
Find a nut to use as a test device. If it will thread down on the old bolt and not on the new bolt, you have your answer.