460 Ford Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
2,615 Posts
Discussion Starter #1
I only use a valley pan IF I'm using the exhaust crossover passage. If the intake manifold or cylinder heads don't have the exhaust crossover passage, then I don't use one. Just my experience and never had a problem. As a matter of fact, some intake manifold manufacturers (such as the Weiand Stealth) actually instruct you NOT to use a valley pan intake gasket.

If your intake manifold and cylinder heads have the exhaust crossover passage AND you're using it, (meaning it's not blocked off) then I'd recommend using a valley pan type of gasket. Remember, Ford used either a valley pan or a small square shaped heat shield (secured with three push rivets) under the factory cast iron intake manifold, in order to prevent oil from baking underneath the manifold (around the exhaust crossover area).

IF you're using an aftermarket aluminum intake manifold AND blocking off the exhaust crossover passage, then a valley pan gasket is not necessary (because there isn't any additional source of heat). If you think that you'll reduce the temperature of the intake manifold, by using a valley pan, your wrong. A valley pan is not an insulator that completely seals off the bottom of the manifold from engine heat, it's only an oil barrier for the exhaust crossover passage. In order to prove my point, David Vizard once did dyno testing on several intake manifolds and his comments on the Edelbrock Air Gap manifold may surprise you. This is an excerpt from David Vizard, after dyno testing several intake manifolds including the Edelbrock Air Gap:

"Exactly what is the Air Gap's air gap worth? Temperature testing with an infrared heat gun revealed much. First, the heat soak from a hot engine will, in about 10 minutes, bring the runners of the Air Gap manifold up to that of a non-air gap one. Under full-power conditions, the runners of either type of manifold drop and stabilize after about 15-20 seconds at full throttle, but the Air Gap manifold drops (depending on ambient conditions) about 20 degrees more at 2,500 rpm and about 15 more at 5,500 rpm. The net worth of this in output is about 6 lbs.-ft. at 2,500 rpm and about 4 lbs.-ft. at 5,500. Nevertheless, there is an overriding concern here. If the carb being used has inadequate fuel atomization, the cooler runners can actually detract from output, so be sure to use a carb that does a good job on mixture preparation."

Now this was on an Air Gap manifold, which in fact DOES have the intake runners completely sealed off from hot engine oil, and it STILL reached the operating temperature of a non Air Gap manifold.

While we're on the subject of intake gaskets (and since some of you won't use the valley pan now), lets just quickly cover conventional intake gaskets. The Fel-Pro 1230/1231 intake gasket is NOT intended for a street application. It is designed with a soft rubber-fiber base (resistant to gasoline & alcohol) AND without a steel core reinforcement so race builders can trim material for a custom port opening. The 1230/1231 is only supposed to be used on a race engine that gets disassembled (for inspection or rebuild) on a regular basis. It was NOT designed to withstand long term daily street usage. This is from my in-depth research on this subject and from speaking to a Fel-Pro technician. People who have used these gaskets successfully on the street, don't put many miles on the vehicle. While there may be a few who contest this, there are many more who will substantiate the 1230/1231 failure streetwise. The Fel-Pro MS901101 (Dove port) & Victor Reinz NitroSeal 95074SG (CJ/SCJ port) intake gaskets are the proper choice for a daily street driven engine that will stay assembled for a long period of time. (Fel-Pro doesn't make a CJ/SCJ 'street longevity' intake gasket set.)

The 1230/1231 intake gaskets also aren't meant for an exhaust crossover passage. They are race only gaskets for aftermarket heads and manifolds without the exhaust crossover passage. If you insist on using these gaskets with an exhaust crossover passage, then you'll need to either cut the opening in the gasket or block it off with a thin piece of stainless steel sheet metal (fitted between the gasket and head). It will burn through, if you don't cut out the opening or block it off with any effective method you choose.

Blocking off the exhaust crossover passage:
The hardware store sells small square pieces (about 4"x4") of sheetmetal (by their ducting material) for less than $2. I used a small thin piece of stainless steel sheet metal to block off the exhaust crossover passage. (It doesn't need to be stainless steel, I just had it.) The important thing to remember is to place the sheet metal between the cylinder head and intake gasket. I coat the cylinder head side of the sheet metal, with a 1/4" thick layer of high temp silicone and push it into position (so the silicone creates a 1/4" barrier inside the heat crossover passage), then wipe off the excess around the outside edge. I recently disassembled my 466 (soon to be a 508") with about 100,000 miles and the sheet metal block off was still right in place (on the cylinder head).

Sorry for the long post, however, I've done alot of research and discussed this, at length, with Fel-Pro technicians.
 

·
Registered
Joined
·
1,603 Posts
Danny, your post is the one I followed and book marked so many months ago. When you say "The important thing to remember is to place the sheet metal between the cylinder head and intake gasket." do you mean the way I did it (lapped under) or should it be cut to the size of the hole in the gasket?

I think I had a gap that allowed oil in in that spot due to the metal keeping the gasket from seating. I used exactly what you mentioned, ducting material, very thin.

As per Scott J I will also smear a thin coat of RTV on the entire gasket in case the intake is slightly out of true. Normally I would only do the water passages but I may have something weird going on here.
 

·
Registered
Joined
·
2,615 Posts
Discussion Starter #3
Phil said:
When you say, "The important thing to remember is to place the sheet metal between the cylinder head and intake gasket." do you mean the way I did it (lapped under) or should it be cut to the size of the hole in the gasket?
The sheet metal should be cut larger than the intake gasket hole and should not be inserted into the gasket. The gasket does not need to be modified in any way. The sheet metal needs to be layed directly on the cylinder head (covering the passage) with a 1/4" thick coat of ultra high temp RTV silicone inside the cylinder head (excess wiped off outside) and a thin amount of RTV silicone between the gasket & sheet metal.

If the sheet metal is placed on top of the gasket (or inside the gasket), then you risk exhaust gas burning the gasket or it moving out of position (since it would be in contact with aluminum which expands & contracts greater than cast iron. Also, this procedure would have to be repeated if replacing an intake gasket or intake manifold.
 

·
Premium Member
Joined
·
845 Posts
I know I should already know this, but what purpose does blocking off the x-over passage serve, is it less heat entering the manifold?

I am curious about this as before I put my engine in my new frame, I am tearing it apart(even though it was only run for less than a year, it has set and only started occasionally for 2years!) and I am gonna maybe change the heads, put all new gaskets in the motor, clean it up and do some other odds and ends stuff i didn't know about when I first built it.

also, how does putting a piece of metal between the manifold and the head, no matter how thing it may be, not disturb the sealing surface between the head and the manifold? wouldn't sticking that metal in there make the middle of the manifold want to sit higher than the ends and cause it to warp when tightening it down? I am prolly missing something here, but enlighten me-PLEASE FILL THE KID IN! :)

-Matt
 

·
Registered
Joined
·
2,615 Posts
Discussion Starter #5
Greenbroncoguy said:
I know I should already know this, but what purpose does blocking off the x-over passage serve, is it less heat entering the manifold?
The exhaust crossover passage heats the intake manifold for better fuel atomization and driveability, especially when cold. In terms of fuel, a cold intake manifold (before engine reaches operating temperature) causes 'plenum puddling' and 'runner wetting'. If you live in a cold climate, I still recommend blocking the passage, however, you can drill a 5/16" hole in the plates to allow some hot air through.

In a performance application, cool dense air creates more power (increasing volumetric efficiency), when fully warmed up (so we'll sacrifice slight cold engine driveability). Also, an aluminum manifold gets extremely hot with the exhaust crossover passage because aluminum conducts heat much greater than cast iron and may cause fuel percolation & vapor lock issues.

Greenbroncoguy said:
Also, how does putting a piece of metal between the manifold and the head, no matter how thin it may be, not disturb the sealing surface between the head and the manifold? Wouldn't sticking that metal in there make the middle of the manifold want to sit higher than the ends and cause it to warp when tightening it down.
No, because the intake gasket will compress around the thin sheet metal plate. High temp RTV silicone is also used on both sides. On my last engine (466"), the sheet metal plates were still in the exact same position after almost 100,000 miles. I even replaced the intake manifold gaskets once, due to a Fel-Pro 1230 failure (hence the reason for above article) and I didn't have to touch the plates at all. I've never had a Fel-Pro MS901101 intake gasket leak with the sheet metal plates installed.
 

·
Premium Member
Joined
·
845 Posts
so with my stealth and DOVE's, this would be a good idea to do this while my engine is apart, with minor ill effects being that I live here in Florida and even here in November it is 80deg. out :)

another question, if I was to plug the thermactor holes in my DOVE's, or use heads like the C8VE-E's im looking at getting that do not have drilled thermactor bosses, there would be nothing comming out of the exhaust X-over passage correct?

and also, would it be a better idea to go with the Victor gaskets from Napa than the Felpro-s since everyone is having problems?

-Matt
 

·
Registered
Joined
·
2,615 Posts
Discussion Starter #7
Greenbroncoguy said:
Another question, if I was to plug the thermactor holes in my DOVE's, or use heads like the C8VE-E's im looking at getting that do not have drilled thermactor bosses, there would be nothing comming out of the exhaust X-over passage correct?
No, the exhaust crossover passage is a separate port (primarily for cold engine driveability/emissions). The thermactor ports were for emissions components.
http://www.460ford.com/viewtopic.php?t=2724&highlight=thermactor

Greenbroncoguy said:
Also, would it be a better idea to go with the Victor gaskets from Napa than the Felpro-s since everyone is having problems?
No, the Fel-Pro 1230/1231 intake gaskets are the problem (with daily driven/longevity engines), not all Fel-Pro gaskets. Read the article again...the good gaskets you want are the Fel-Pro MS901101 (DOVE port heads).
 

·
Premium Member
Joined
·
845 Posts
Danny Cabral said:
No, the exhaust crossover passage is a separate port (primarily for cold engine driveability/emissions). The thermactor ports were for emissions components.
then where does the exhaust gas that flows inside the exhaust crossover passage come from, there is no other place to take exhaust gas from but inside the exhaust port is there? I say this because my dad's set of C8VE-E's did not have the thermactor holes drilled, but it did not have the crossover passage blocked off either and inside of his crossover passages in the heads and the intake(stealth) were both clean when we took the motor apart.

-Matt
 

·
Registered
Joined
·
2,615 Posts
Discussion Starter #9
Greenbroncoguy said:
Then where does the exhaust gas that flows inside the exhaust crossover passage come from, there is no other place to take exhaust gas from but inside the exhaust port is there?
The thermactor passage is a separate casting than the exhaust crossover passage. Not all cylinder heads have the thermactor passage drilled but they all have the exhaust crossover.
The exhaust crossover sources it's exhaust from one of the center exhaust ports. The thermactor passage is connected to exhaust by holes in each exhaust port.
 

·
Premium Member
Joined
·
845 Posts
Danny Cabral said:
The exhaust crossover sources it's exhaust from one of the center exhaust ports. The thermactor passage sources it's exhaust from holes in each exhaust port.
so then, there is a seperate hole in one of the exhaust ports other than a therm. hole(assuming there is a drlles therm. hole and if not then there would just be oe hole in that port?

Danny, please know I am really not trying to argue with you here, I just want to understand a little better so I kow how to go about doing up my heads before I put her back together.

-Matt
 

·
Registered
Joined
·
2,615 Posts
Discussion Starter #11
Greenbroncoguy said:
so then, there is a seperate hole in one of the exhaust ports other than a therm. hole(assuming there is a drlles therm. hole and if not then there would just be oe hole in that port?

Danny, please know I am really not trying to argue with you here, I just want to understand a little better so I kow how to go about doing up my heads before I put her back together. -Matt
At this point, I suggest you position a cylinder head on your workbench and locate/identify these passages with a piece of mechanics wire. This will clearly answer all your questions.
 

·
Premium Member
Joined
·
845 Posts
will do. this is the route I was planning on anyway, as I know you are bound to get agitated with me asking all these questions! :)

sorry for acting like such a n00b!

-Matt
 
1 - 13 of 13 Posts
Top