Over the summer I swapped a rebuilt 300 into my 78 f250, the new engine runs awesome but my headers leak and sounds awful. I've taken them off twice now and just cant get them to seal up. I've tried different gaskets and the copper rtv sealant. What's the secret? What type of studs/bolts work best? The truck has a Clifford intake with 4 barrel edelbrock, and I'm unsure what brand headers?
Any help is much appreciated,
thanks in advance!
-Tyler

 

Please delete

 

Pull the header/s and check the flanges. If the flanges are severely warped or the welds aren't flat you'll never get them to seal. I like to get a roll of adhesive backed sand paper ( 80 grit or coarser ) . I like the 4 1/2" wide stuff. Then stick it down on a large flat/true area ( piece longer then header flange ). I like to use a piece of steel plate on a work bench. Run the header, flange side down, across the sand paper. Doing this will show areas that are warped/ not sealing. Then depending how severe the problem areas are you can keep running it across the sand paper or carefully take a grinder to it. If you use the grinder make sure to run it back over the sand paper often to check it.



The other areas to check is the flange thickness compared to the thickness of the intake flange where the mounting bolts seat. If the intake flange is thicker then the header flange, the header isn't going to seal. If this is the case you can either grind down the intake flange which weakens the mounting ears. Or build up the header flange. I've done this in the past by cutting washers in half and then tack weld them to the header flange. The other option is to take some thick washers and mill down the one side and put them on the mounting bolts.




For the gasket I'm going with the Remflex one BruteFord posted on my 240/300's. Not cheap but a damn good gasket.

 

Fordman has good advice. I'd also use Hillco dot com 2"-2.25" x3/8" inch grade 8 studs. The end into the head is coarse threads, other end is fine. Use crimp nuts and the oem thick washers. I ground down my washers to compensate for the diff. thicknesses from int.to header.

Use the Mr.Gasket 260, tighten from center out in a spiral according to torque specs, heat to running temp, let cool, retighten, repeat and forget about it. Five years, never had a leak. Good luck. k

 

Ford man, where do you find the adhesive sandpaper? I had heard of people taking the headers to a large belt sander, but your approach is a lot simpler to obtain.
f250 restorer, do you know what the torque specs are for headers?
thanks for the help.

 

Belt sanders are great if you have access to one that is long enough. I've just got a short belt sander and I like to do the work myself. So the sandpaper on a work bench is a way I could do it.


You can get the sand paper rolls at a lot of places. I shop around to find the best prices. But the easiest is to just do a search for them. I've bought them off amazon, ebay, MSC, etc.

Here's a google search for "Adhesive backed sandpaper rolls, 4 1/2":

https://www.google.com/?gws_rd=ssl#q...%2C+4+1%2F2%22

Here's one at amazon:

 

Check any owners manual for the torque setting and sequence. Iirc it is 22 lbs. Some one please correct me if that is not correct. Also, snug tight all the bolt first in sequence, then come and torque to half the total, and finally, torque them in sequence to total amount. The manuals give a certain sequence. I simply begin in center and move in clockwise or counter clockwise spiral. Oh, and put the copper anti-seize compound on the stud threads that go into head.

Remember: It is very important to run it, let it get completely cool, and retorque, and do the procedure TWICE. k

 

I fought with mine for a while. I went to doubled factory replacement gaskets with permatex ultra copper silicone. I also went to slightly longer bolts and stacked some bigger washers under the thick factory washers.

 

Good advice F250, exactly what I did , Hillco, (Grade 8), I to ,used the mr gasket with no problems , heated it up let it cool re torqued (Clifford intake)! TR

 

Assuming the headers have thermal-cycled enough times to stress-relieve themselves to some extent, and will more or less stay put after you have squared up the flange faces, And that you don't have easy access to a super-long belt sander or milling machine, AND that you don't want to spent several days trying to grind all the flanges down at once with a long-board and sandpaper, . . .

. . . how about just get a long very flat bar (cold-rolled mild steel that's wide enough and thick enough to be truly flat) and mark your flanges with machinists' high-spot bluing dye (a little tube of Prussian Blue), and keep spot-grinding the high spots down with a little 4 1/2" side grinder. Eventually you'll get it all reasonably even to where it might seal with no more effort, although you could do some final flattening with the long board.

I just think you'd grow old trying to square it all up with a long board. That tube of Prussian Blue is something you'll have occasional use for all your life. A 4 1/2" angle grinder is one of the most useful tools ever invented, once you have a little selection of grinding disks, sanding flap-disks, thin cut-off wheels, and a couple of kinds of wire wheel. As a welder, I have half a dozen (and a box of dead parts-doners), and use them daily, even when it's not a welding project. If you don't use these little angle-grinders professionally, Harbor Freight stuff will do, including their grinding disks and wire wheels. But do not buy their cheapest little black grinder; get the next step up, now usually about $25 on sale, which they nearly always are. If you have never owned a little side-grinder, you'll wonder how you ever got along without one. Grinding/cutting off old bolts is frequently a big time-saver.

Harbor Freight "Chicago Electric" grinder, the one to get: Heavy Duty 4-1/2" Angle Grinder

Harbor Freight "Drillmaster" grinder, the one to avoid: http://www.harborfreight.com/4-12-in...der-69645.html

 

I never said use a board. You just use the flat surface with sand paper to show the high/low spots. I said to use a grinder to flatten things out.

 

Thats a great idea using the Prussian Blue. My father was a machinist and I remember seeing a tube in his tool box. It takes a good bit of skill and experience not to over grind with a hand grinder. I would probably use both the grinder and flat surface.. We have an old table saw with cast iron table top we cant get a new motor for. It makes a great flat surface to do work like this on..
$21 is a good price for a small grinder and it is small enough to get into tight places..

 

I wasn't answering you specifically, Ted, and didn't notice your mention of a grinder. Sorry.

"Long-board" was a generic term used in a shop where I worked for a 4' length of aluminum plate with adhesive=backed abrasive from a 6" wide roll, maybe 36 grit. Yep, you could use it to find high spots in the same way you could use bluing. But a roll of the abrasive was expensive and the dye is cheap.

We also applied the abrasive to flexible backings (i.e., 1/8" marine plywood) for bodywork and boat-building.

If a hard grinding disk takes of metal too fast, there are abrasive flap-wheel discs to fit the side-grinder, and they come in a range of grits.