Interesting Discovery

1Trkpony · #1 (**permalink**) 03-04-2005, 10:05 PM

I am in the process of tearing down my shelby 427FE to do a cam swap (see "Now thats a Cam" thread). It is going pretty much as I expected, just takes time but no real problems. I finished tearing it down tonight and got the cam out. When I pop'd the intake (shelby MR dual plane) I discovered that the intake gaskets (Fel-pro print-o seal 1247 for MR heads) had failed on three of the ports (#1, #5 and #8). See attached picture of #5 port. Each of them failed in the same way by tearing right at the edge of the port. Of the failures I know #1 was a vacuum leak as the intake port has oil residue on it compared to the others. The others might have been leaking too. This was more then likely part of my idle and low vacuum problem I was chassing with my cam. Oh well I guess it was good I was tearing it down and found this.

My question is why did these gaskets fail? The engine was assembled by Carrol Shelby Ent. in '99 and has about 6K miles on it. Also because it has medium riser heads, the only gaskets I found were the Fel-pro 1247s the same that were on there. I guess I will have to keep an eye on them in the future and expect to replace them regularly.

One nice discovery is that I found out my shelby heads are fully ported (I thought they were as cast). Also the shelby rocker assembly is pretty trick looking and very stout. Working on this engine is very interesting because I get to see the insides and find out exactly what is there...

1Trkpony · #2 (**permalink**) 03-04-2005, 10:11 PM

Naked engine!!!

1Trkpony · #3 (**permalink**) 03-04-2005, 10:13 PM

Very nice, too bad they are under the valve covers...

John Martin · #4 (**permalink**) 03-05-2005, 05:17 AM

There are better intake gaskets , Victor Reinz " Nitroseal " Part # 95159SG

2.40 by 2.34

ERA Tom · #5 (**permalink**) 03-05-2005, 05:22 AM

I would stay away from the Felpro intake gaskets on any FE, they have a reputation for failing. Go with the Victor Reinz "Nitroseal" part number 95159SG, availble through NAPA stores. - Tom

KrAzEcJ · #6 (**permalink**) 03-05-2005, 01:23 PM

I cant be sure but those look like the 1230 series "soft rubber-fiber base" ones without a steel core reinforcement so race builders can trim material for a custom port opening. The 1230 is only supposed to be used on a race engine that gets disassembled on a regular basis. It wasn't designed to withstand longterm daily street usage. Again, I could be wrong on what type your using but I don't see any metal showing in the gasket where it failed between ports.

1Trkpony · #7 (**permalink**) 03-06-2005, 08:20 AM

Nope these are 1247s, says right on it. But yes these do not have metal in them at all just fiber and the "printoseal". Either way not good for them to fail so soon.

cobra427mnsi · #8 (**permalink**) 03-06-2005, 01:09 PM

1Trkpony

Your roller rockers are the same as the ones I got from FE Max except for the lettering. Gary at FE Max mentioned that he made them for Shelby until they had a falling out because Shelby wanted an exclusive right to sell them but Gary wanted to continue selling them minus the Shelby lettering. You're right about them being too beautiful to be covered by valve covers. I have been looking for lexan FE valve covers but no results so far.

Paul

cobra427mnsi · #9 (**permalink**) 03-06-2005, 01:11 PM

Here is a close up. These rockers are made from stainless steel.

Jack21 · #10 (**permalink**) 03-06-2005, 02:15 PM

Something else to check. Lay a straightedge across the intake deck, and intake manifold. If it's warped, skin it until it's flat again and it will seal better. Also, a small bead of RTV around the water passages helps keep the seal.

SCOBRAC · #11 (**permalink**) 03-09-2005, 07:49 PM

I know I'm going to get hammered for this but the Shelby heads are not standard FE castings. They should have developed a better gasket (or at least found one that fit). Look at the water passage photo. Maybe they are using prison labor on their engine builds too. The best gasket maker is RTV USED VERY SPARINGLY (ok hammer away).

I always use a small amout of RTV on the head side and have never had a failure.

Those rocker arm assemblies are really cool... Why'd you take them off if you are just replacing the cam?

GEORGE ANDERSON · #12 (**permalink**) 03-09-2005, 09:43 PM

The Victor 95159SG Nitro Seal is a gasket that will last(as several posts mentioned)....the Felpro 1247 just won't last...you did well making it this long without a problem...the 95158SG is the Vidtor number for 1246 Felpro.....(updated 3/10/05 AM)
you get good advice on Club Cobra
George

cobra427mnsi · #13 (**permalink**) 03-10-2005, 04:07 AM

George

The number you gave is different than the number posted earlier (95158SG as opposed to 95159SG). Which is correct or are both correct?

Paul

GEORGE ANDERSON · #14 (**permalink**) 03-10-2005, 05:59 AM

Thanks for the correction Paul...I corrected the above post
G

1Trkpony · #15 (**permalink**) 03-10-2005, 09:45 AM

Why take off the rockers to remove the cam? To take the intake and lifters out the rockers need to come out too. At least that is what I thought. On RTV, yep I do the same around the H2O ports, head side only.

Update and bad news on the progress: One of the stainless steel inserts for the rocker bolts would not take a 40 ft-lb torque (the one with the oil hole). Long story short that head is off to Shelby to be repaired, no charge (thanks Shelby!). Also swaping the bolts out for studs which they should have been in the first place I am learning. Good news is that the head came out with the engine in the car as luckily it was the passenger side.



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