And the lesson is retighten your header bolts.

[cgrey8]

Since these gaskets were made for standard 302 headers and these are FMS GT40p headers, there may be a mismatch in the port sizes however the ports in the gasket looked plenty big enough to fit around the holes in the header but maybe the holes were just slightly too small for the header.

I've still go to take the time to get the Fel-Pro gasket into mine. When I was putting the coppers in, I didn't have an extra Fel-Pro to tear everything back apart and install. Now that I have replacements, I'll be putting it in tonight. Hopefully after just have taken everything apart once, it'll be easier to do this time around since I'll know exactly what needs to be moved. It's still discouraging though...

[Warpig Racing]

did you replace your gaskets yet? Did you compare them?

[cgrey8]

I replaced the copper gasket last night and put a Fel-Pro back in its place. No more leaks around the gasket as far as I can tell. Looking closer at the copper gasket to see what was wrong, it appears the O-ring lip on the port was about 1/4" too high. It was pinched down almost everywhere except at the bottom. As well, I could see the exhaust path as it flowed right over the uncrimped ring section and straight down.

I wrote MrGasket asking if they were aware of the incompatibility with FMS Explorer headers. I haven't gotten a response yet.

[cgrey8]

I did receive a couple of replies back from MrGasket about issues with their gaskets, none of which was honoring any kind of satisfaction guarantee or suggesting I contact their Customer Service for a refund. They did tell me those lock washers that were included with the copper gaskets sell separetely. Summit has them for about $6, but I imagine after s/h, you could get them cheaper at AutoZone or O'reillys.

PN 3418 is 5/16" id
PN 3416 is 3/8" id (what 302s use)

The downside is they sell in packs of 12. I guess since SBCs only take 12 bolts, suppliers don't think/care about SBF customers that need 16. I've noticed they aren't the only company that sells header bolt kits in packs of 12 ONLY. Point being, if you plan to use their washers, you'll need to buy 2 kits which probably isn't a bad idea anyway. During the removal of the copper gasket, I found one of the lock washers had cracked. Having a few extras probably isn't a bad idea. Had these experienced high heat conditions, I could've expected this behavior, but being the truck was run for a total of 3 minutes with the copper gasket installed, I doubt heat exposure was the problem. I think it was just a bad washer.

If anybody else knows of some alternate header washer suppliers, I'd be interested to hear about them. I wasn't impressed with MrGasket's responses or their handling of this problem. They didn't seem to care that their product didn't work for me nor did they offer any kind of refund.

If I ever do try an alternate exhaust gasket material in the future, it'll likely be Percys reusable aluminum gaskets. I believe they would've worked with these headers. The problem is they are so thick, there's no way I could use the header bolts that came with my FMS headers with these gaskets AND use the lock washers. I'd have to buy split-tip locking header bolts. On Summit, the cheapest set of locking header bolts I found were nearly $40 and they went into the high $70s.

[87ranger]

I've allways ran the felpro 1487 gaskets on my ford motorsport j302 heads, it's a steel gasket with a high temp coating.

[87sc302]

I had alot of leakage problems when I first built my engine and after trying ever type of gasket I realzed the problem was a mis match of the header port (rectangular) and head (square). In desperation I (temporary fix)installed set of cast exhaust manifolds till I could find the correct header and two years later I sometimes think about going back to headers. This is a daily driver and very easy to maintain.

Summit was advertising that they carry the header bolts that are split and use the hex screw in center to lock, they looked pretty neat.

[cgrey8]

My FMS headers were specifically designed for Explorer motors. If there is a mismatch in header to head, that would be a SNAFU on Ford Motorsport's part.

In reality, the ports on the GT40p heads are suprisingly small. The openings on the headers are huge in comparison. There's an enormous amount of room for porting those GT40p heads out on the exhaust side. The Fel-Pro gaskets I have match to the header using rectangular ports...at least the Fel-Pros do. The copper ones were slightly too small on the rectangle, but are the rectangular style. The coppers would've worked on the factory manfolds without a problem.

Personally, I could care less whether there's a $5 gasket or a $50 copper gasket between the header and head. Whatever's there, I just don't want the bolts working themselves loose every 2000 miles causing it to leak. I believe the lock washers will be the cure for that. Time will tell though...

[cgrey8]

Reviving an old thread. While looking closer at the Exhaust Ports with a gasket, I decided to pull out those old copper gaskets I bought a few years ago. We always wondered why the MrGasket Copper Gaskets never worked right using the FMS Explorer headers. For those that don't remember what the problem was, they leaked at the bottom edge of the gasket. Here are some pics showing why:


In this pic, you can still see some of the black soot from where this gasket was leaking.

Here are some shots of the gaskets actually sitting on the heads:



Interestingly both gaskets align with the ports in the head, it's just one gasket aligns with the top of the port and the other aligns with the bottom of the port. I suspect installing the Copper gaskets upside-down would make them align better. I didn't think of that when I had the camera out. If I think about it tonight, I'll get some shots of what the gaskets look like put on the head upside-down. If it looks like they'll work that way, I may retry them when I put the 331 in. But to be sure, I'm not going to use the Copper gaskets as a template for the porting. I'll be using the standard Explorer gasket as a guide.

[MalcolmV8]

Yup they don't work. I have a set of those copper gaskets laying in my garage unused from back when I tried them.

[Teddyzee]

I gasket matched my heads to the gasket, then didn't use any gasket at all... Just copper sealer.

[cgrey8]

That's impressive that just copper sealer works. I'm impressed that's actually holding up for you.

BTW, I pulled out the copper gasket and turned it upside down against the Explorer gasket, and it didn't line up that way either...not even close. Those gaskets are either not stamped correctly or GT40p heads locate the port differently than traditional heads that those copper gaskets were made for. I did notice that slotting the bolt holes in the gaskets so the gasket sits lower would also fix the problem. I'm still not sure I want to trust it knowing that the normal Explorer gaskets can last if you get the bolts in with lock washers that don't let the bolt come out. And for the bolts that I couldn't get the washer on, putting orange silicone gasket on the threads kept them in all these years.

[Teddyzee]

That's impressive that just copper sealer works. I'm impressed that's actually holding up for you.

Me too... I was following along to see what everyone did to cure leaks on sbftech.com , and many said they used no gasket at all. I tried it, and it's a success.

And for the heck of it, because we all like pictures, my before/after: (...maybe that's during, not after, but you get the idea)

[cgrey8]

Gasket-matching the exhaust port works well on the E7 heads, but it isn't a good idea on the GT40p heads. You actually loose out on flow you could've gotten by not doing that. That seems counter-intuitive until you realize why. The shape of the bowl caters flow to one side of the port on exit...the top-left. At low valve lift conditions, this creates a swirl effect that you really don't want in the port where literally the bottom-right corner has flow INTO the head. There's actually a vacuum at the bottom of the port pulling exhaust back in. Even at higher lifts, this condition is still there, although you do start to get positive flow at the bottom-right...but the tendency and desire to backflow is still there causing a flow restriction in the port. So removing metal on the right side of the port is not recommended at all. Removing metal on the left side though seems to do the trick though. The guy on the diyPorting.com site found that the following was the optimal port shape on GT40p heads:

Notice how it has an oblong shape across the top with the left side being higher than the right and at the bottom, only the left side is shaped. It's this characteristic that people often talk about when they say if you go hogging out GT40p heads like they were conventional E7TE heads, you miss out of flow you could've had.

The intake port is pretty well cast as-is. There's only cleanup work in the bowl to get rid of sharp edges, the valve guide girth, and shape the runner.

[Dave]

My intake ports on the AFR's are about the same as the gaskets but .10" down from the top and up from the bottom, sides are perfect match to the gasket. Instructions say "Do not port to match gaskets". Not to question the masters. This is shot down the intake and the machined in ramp/flow diverter they have in there. They have the same on the exhaust. These are the standard CNC machined ones. Like Chris said, what seems to be logical is not always best.
Dave

[cgrey8]

There is no way I could shape a port that nicely. Porting bits on a hand held grinder bounce around way too much for me to form up a ramp that perfect. An experienced porter could probably do it. But for me, the only way I'm getting that kind of port/bowl perfection is buying it from someone that used a CNC machine to get that.