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Junior Charter Member
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Discussion Starter #1
I have a Mark II with a 351W engine and FFR header, with. 2” tall port. What exhaust gasket is everyone using?
 

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Do you know what brand/model the cylinder heads are? Hard to make a specific part number recommendation for a gasket without knowing which head is on there. Sometimes even then, the FFR (Hooker) header ports aren't a great fit for the exhaust ports and leaks are a common symptom. Fewest complaints come from those who go without gaskets and simply use high-temp silicone instead. My AFR cylinder heads recommended a Fel-Pro #1487 gasket, but this won't fit an OEM Ford cylinder head.

Sean
 

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I haven't used a header gasket in many years. Silicone only.
 

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I haven't used a header gasket in many years. Silicone only.
3 years ago, I did what Bob said to do. High Temp Silicone only. Certainly eliminates the slight mismatches between head port and header flange. So far so good, no problems.
 

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FFCobra Craftsman
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22,703 Posts
Use this
But do make sure your header flange is flat. Many of them have the weld bead just slightly proud of the flange surface so that needs to be ground flat. I use a big flat file to go over the surface lightly moving it diagonally. Any place that shows file marks is high. I take that down w/ a grinder or or palm sander w/ 16 grit paper depending how much needs to be removed. Then I go back to the file moving it on the opposite diagonal. When it's time to install it on the head you have to be real careful to not wipe some of it off on something. I use a couple of studs (w/ a screw driver slot cut into the end) installed just finger tight in the front and rear most holes. They provide guidance and let me sit the header on them, hold it w/ one hand while I start threading in bolts w/ the other hand.
 

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Discussion Starter #6
I have Edelbrock Vic JR 351 heads with a 1 3/8” tall port. The FFR supplied 4 pipe header has a 1 7/8” tall port. When I built the engine 15 years ago, it’s a Mark II, I did not notice the miss match and just ordered Fel Pro gaskets for the Vic JR heads, which fit great. But of course they don’t fit the FFR headers very good, causing minor likes where the header is taller than the head.
I called FFR yesterday and they couldn’t tell me what head they used to design the headers to fit. All they remembered was that it as “Z” head. I have done some research at Jegs and Summit , I’ve found some high performance “Z” heads, but none of them have a 1 7/8” tall port, from the info I can get from their web site.
So, this must have been going on with all FFR header gasket fits.
Any help out there ?
Paul
 

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I have Edelbrock Vic JR 351 heads with a 1 3/8” tall port. The FFR supplied 4 pipe header has a 1 7/8” tall port. When I built the engine 15 years ago, it’s a Mark II, I did not notice the miss match and just ordered Fel Pro gaskets for the Vic JR heads, which fit great. But of course they don’t fit the FFR headers very good, causing minor likes where the header is taller than the head.
I called FFR yesterday and they couldn’t tell me what head they used to design the headers to fit. All they remembered was that it as “Z” head. I have done some research at Jegs and Summit , I’ve found some high performance “Z” heads, but none of them have a 1 7/8” tall port, from the info I can get from their web site.
So, this must have been going on with all FFR header gasket fits.
Any help out there ?
Paul
You are exactly right. The head exhaust ports and the header flange do not match very well. I took this picture about 10 years ago. You can what is happening at the bottom of the port.


After that, I used silicone only. So much cheaper and easier. Perfect fit every time.

I was talking to a drag racer one day. He uses clear bathtub caulk because it looks better. But he does a tear down after every week end.
 

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Just a suggestion, look into remflex gaskets. You'll still need to figure out the measurements but they should hold up better than felpro.
 

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The best suggestion is follow Bob and Craig's recommendation, and don't use any gaskets, just the Ultra Copper Maximum Temperature RTV.
 

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FFCobra Craftsman
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I had forgotten about the header/gasket mismatch but now I remember. Bob' pic is exactly what I had. And that is why I switched to glue. Now I had full header flange to head contact. One other thing to look at carefully because it's hard to see. Many heads get wider below the exhaust port to the head gasket surface. Some header flanges are a little over sized and the edge of the flange contacts the flared out part of the head. That holds the flange away from it's mating surface by just a tiny bit. I ground a chamfer on the bottom edge of my header flange.
 

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Silicone too, Ultra Copper Max temp. Over 5K miles and no leaks. Put a bead on the header, install, and finger tighten your bolts. Use a socket to tighten if you have fat fingers. Torque the next day. I used Stage 8 locking header bolts too.
 

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Junior Charter Member
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I also use Ultra Copper and have had good luck. I did have to redo one after 23k miles. My gaskets didn't make it 5k.
 

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I agree with Craig S. I used the Permatex copper, and it's been perfect for 9 years.
 
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