Header gasket recommendations

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I would recommend Remflex header gaskets   http://catalog.remflex.com/category_s/99.htm

Best to call them to get best gasket for your setup.  I use them with my Hedman shorties on my 302 with the Holley EFI.
I used the Remflex too on my 1970 F250 with a 360 FE. Expensive but worth it! But be careful - they broke easily if you bend them by accident. Don't ask how I know... I used them on the original heads and the original exhaust manifolds I overhauled. I cleaned and flattened the gasket sides of the manifolds and I was not sure about if they are totally flat although they seemed so. Therefore I used the Remflex gaskets and all leaks were gone. 

 
I've had good luck with both cometic's gaskets and the copper crush style others have mentioned. If there's anything to avoid, I'd say it's the cheaper gaskets that have the fiber material embedded. They will seal fine the first time, but have a tendency to get brittle and leave material stuck to the heads/header when you take them off.

 
Put a THIN coat of the RTV of your choice on both sides of the gasket and tighten from the middle to each end. Let the RTV completely cure, about 24 hours. It will seal and will not burn out. If it is completely cured it will not harm the oxygen sensor. Chuck

 
Another problem with the cheap fiber center gaskets is that the fasteners never stay tight, the gaskets are always expanding, shrinking, compressing.

There's nothing wrong with NGK plugs, but I would probably start with UR4s, run it for a while and then pull a couple and see how they look.

I'm probably going with the E3 plugs (E3.42), now that Bosch stopped making their Plus4 plugs. I like the multiple fire points on the plugs, less chance of getting shrouded. And there's a reason that aircraft reciprocating engines have multiple ground electrodes.

 
Also, my builder suggested NGK UR6 spark plugs. It's a 408c, mild cam and stock iron heads. While he's a great engine builder he's not a Ford guy. Do this plugs sound optimal?
I was recommended NGK R5673-7  for my 408. I will be giving the R5673-6 a chance since I think they could be a little hotter.

 
Another problem with the cheap fiber center gaskets is that the fasteners never stay tight, the gaskets are always expanding, shrinking, compressing.

There's nothing wrong with NGK plugs, but I would probably start with UR4s, run it for a while and then pull a couple and see how they look.

I'm probably going with the E3 plugs (E3.42), now that Bosch stopped making their Plus4 plugs. I like the multiple fire points on the plugs, less chance of getting shrouded. And there's a reason that aircraft reciprocating engines have multiple ground electrodes.
I'll have to look into those. 

 
I have had excellent results with the simple white fiber gaskets that Hooker headers sold in the past. I used a bead of Ultra Copper around each port, let it set up for 15 mins or so, and then install. Retorque the bolts after the first heat cycle and I'd be good to go for years. The most recent set of Hookers I bought now come with a metal core grey fiber faced gasket that blew out on one port in a few minutes on the dyno. I may or may not try a them in the car with the UltraCopper bead when I drop in the 351C. 

As an aside, the exhaust on my 71 was installed in 2003 and I haven't touched it since. No gasket changes, no retorque of the bolts, nothing. I recently removed the pipes and mufflers, and the collector gaskets looked great. Again, simple white fiber parts. I hung the exhaust so there was maybe 3/4" of movement at the tip and these lasted 18 years without signs of failure. I'll post a pic of the header gasket when I get them off later this week.  The point here is it's often less about the material and more about the technique used. 

collector_gasket_interface_solutions.jpg

 
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I see the torque spec on the Remflex is 20ftlbs. Is there a specific sequence to tighten these in? Looks like the Remflex 3007's are the correct ones for 351c 4v
I typically start in the middle and work my way out - alternating right and left - to the ends.  Start snug, then torque.

 
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