Header gaskets.....best way?

[Viet Nam Vett]

and when you tire of the 502 and move up to a 572 you will have to do it all over again.

Yeah.. but I'm smarter now.

 

[Kid_Again]

Great. Just great.

I have a bolt box with an assortment of bolts from Gr2 to Gr10, some stainless, some steel, some Chicom, some original head stamps. It's an old cigar box.

JohnZ has his bolts boxed, bagged and stapled.


I've GOT to have Jeeves straighten out MY GARAGE!!!!! Too busy polishing the Bentley.

 

[firstgear]

Great. Just great.

I have a bolt box with an assortment of bolts from Gr2 to Gr10, some stainless, some steel, some Chicom, some original head stamps. It's an old cigar box.

JohnZ has his bolts boxed, bagged and stapled.


I've GOT to have Jeeves straighten out MY GARAGE!!!!! Too busy polishing the Bentley.

seems to me that you are too busy with the woman at your TABLE!!!!

 

[JohnZ]

A brief treatise on why ordinary bolts will ALWAYS loosen up on headers:

Stock exhaust manifold bolts are 1-1/2"-2-1/2" long; when tightened to proper torque, they will stretch slightly, which creates the clamping force that holds the joint together - that clamping force remains in the joint due to the tension created by the bolt stretch, which is more than enough to compensate for expansion/contraction resulting from heat cycling.

Header bolts are typically only 3/4" long (due to the thin flange vs. the thick casting on stock manifolds), and that's too short for anywhere near normal torque to actually stretch the bolt; installation will create the clamping force in the joint, but since there's no bolt stretch, that force can't be maintained with heat cycling, and the bolts eventually loosen up, requiring regular checks and re-torquing to prevent exhaust leaks and/or blown gaskets at the header-to-head interface.

That's why a mechanical means to prevent header bolt loosening is necessary, such as Stage 8 locking bolts or safety-wiring. You could accomplish the same thing by using stock manifold bolts with heavy tubular spacers between the bottom of the bolt heads and the header flange so you'd have bolts long enough to stretch and maintain clamping force, but that would be kinda ugly.

 

[Viet Nam Vett]

A brief treatise on why ordinary bolts will ALWAYS loosen up on headers:

Stock exhaust manifold bolts are 1-1/2"-2-1/2" long; when tightened to proper torque, they will stretch slightly, which creates the clamping force that holds the joint together - that clamping force remains in the joint due to the tension created by the bolt stretch, which is more than enough to compensate for expansion/contraction resulting from heat cycling.

Header bolts are typically only 3/4" long (due to the thin flange vs. the thick casting on stock manifolds), and that's too short for anywhere near normal torque to actually stretch the bolt; installation will create the clamping force in the joint, but since there's no bolt stretch, that force can't be maintained with heat cycling, and the bolts eventually loosen up, requiring regular checks and re-torquing to prevent exhaust leaks and/or blown gaskets at the header-to-head interface.

That's why a mechanical means to prevent header bolt loosening is necessary, such as Stage 8 locking bolts or safety-wiring. You could accomplish the same thing by using stock manifold bolts with heavy tubular spacers between the bottom of the bolt heads and the header flange so you'd have bolts long enough to stretch and maintain clamping force, but that would be kinda ugly.

Heh......I enjoyed that.....And I like the Ugly part...That's a Bubba Thing

 

[bossvette]

You could accomplish the same thing by using stock manifold bolts with heavy tubular spacers between the bottom of the bolt heads and the header flange so you'd have bolts long enough to stretch and maintain clamping force, but that would be kinda ugly.

ya but just think if you had the header bolts out that far you could fab up something to mount an old set of Hemi valve covers to and run the spark plug wires thru the covers; that would get the "numbers matching" gang in a tizzy

 

[firstgear]

ya but just think if you had the header bolts out that far you could fab up something to mount an old set of Hemi valve covers to and run the spark plug wires thru the covers; that would get the "numbers matching" gang in a tizzy

not as long as the numbers on the valve covers were proper restamped (no messed up broach marks), then they would be happy, but you have to watch the borach marks!

 

[IH2LOSE]

I also have the sanderson block hugger headers,They are designed for a silicone seal. The weld at the flange actually stands a little proud of the flange and that's where you put the sealant. I am normally not a header type of a person as I never had a set that didn't leak in short time no matter what fastener or gasket I used.

So far these have been leak free.

 

[bossvette]

here is a local C1 with a set of fake valve covers on a blown 283
not a good picture but the best I can do; the car shows up pretty regular when the weather is nice its a 59 or 60

When your done with you car Herb you'll have to come out to the Bryan Ohio cruise in and park near by.

 

[firstgear]

When your done with you car Herb you'll have to come out to the Bryan Ohio cruise in and park near by.

you got a deal......now I just have to get it done!

 

[bossvette]

you got a deal......now I just have to get it done!

You have about 7 months untill next seasons Cruise-ins start the best one to make will be the middle of June grand cruise. Let me know I'll throw some steaks on the grill and we'll have a good ole time.

 

[motorman]

if the header flange is ground smooth you will have problems with sealing. you need a projection to "bite" into the gasket to make the seal. also sawing the header flange into sections will help. i have used a wire welder to lay a bead around each tube on the head side of the flange to give the pprojection to seal into the gasket. all the NASCAR engine builders use hi temp sealer on the header flanges