Header hardware prep

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Evan Dutch

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Hello

I just pulled the factory manifolds off of a 1974 318 (after soaking the bolts/studs in penetrating oil over the course of a few days), in favor for a set of headers.

How should I prep the new header hardware before I install the headers? Should I anti seize them or apply some kind of rtv (thread sealant). I’m unsure of wether or not the bolts thread into water jackets. Heads are still cast iron if that has any affect on the anti seized used.

Thanks
 
Plan on Permatex teflon paste or the like, the bolt holes are wet.
 
Really? I ran a tap through the holes to clean them up and it seemed like it bottomed out.
It may be different on later heads but on 71 model 675 heads they are wet. A punch and a few gentle hammer taps will let you know if it’s iron or corrosion at the bottom of the holes. If they are blind bolt bosses, then ultra copper antisieze or the like. I don’t have them myself, but really like the stage eight locking header bolts.
 
It may be different on later heads but on 71 model 675 heads they are wet. A punch and a few gentle hammer taps will let you know if it’s iron or corrosion at the bottom of the holes. If they are blind bolt bosses, then ultra copper antisieze or the like. I don’t have them myself, but really like the stage eight locking header bolts.
Do I have to use copper antisieze or will any antisieze do?
 
The copper or aluminum paste work best at the high temperatures. I have had good luck with the copper spray on the gaskets. When things have gotten really intense with exhaust temps and sealing issues, I’ve had good luck with Percy’s dead soft aluminum header gaskets in the past.
 
Even when using the aluminum gaskets, I would clean with brake cleaner and spray with copper gasket sealer. If it’s a gasket, I use it. Being somewhat trained by a Harley MMI master technician, I have almost zero tolerance for leaky gaskets or messy wiring.
 
The end bolts are wet . I use Percy's after prepping with brake cleaner or mineral spirits . After installation just snug up bolts . Start motor , let it warm up , snug up again . DO NOT OVERTIGHTEN . I made a special wrench which I keep in car . It's a PITA but eventually the gasket will take a set and stop leaking .
 
We use hi temp RTV on the end bolts that are wet, no problems in 18 years.
 
You could use teflon, I've used RTV, antiseize. Usually they will "self seal" after a few days, LOL
 
On the tightening of the bolts, the center ports are the ones that cause the most grief because over tightening can cause the flange to warp and how outwards which will allow leaks and sometimes really bad ones.

Just tighten them up lightly and carefully. They only needs a few inch pounds. Just enough to stop the leaks.

IMO, use an upgraded exhaust gasket. I have excellent luck with Mr. Gasket Ultra Seals but ANY gasket used should be tightened easy and evenly. The end bolt holes are set and I normally reinstall studs to “hang” the header and gasket for installation.

I use a shortened open end wrench to get some of the tighter bolts. On the drivers side, cylinders 1 & 7 tend to have tight bends on the inside bolts. Start those first. Then do the others.
 
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