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An Essay on Sealing a 440 Mopar Intake Manifold

One Man’s Story


I am getting close to wrapping up my 440 stroker engine build: a Mopar 440 stroked to 511 cubic inches. So I began some research into the proper and recommended way to seal the intake manifold. I had replaced intake manifolds on many occasions, but a) this would be my first time on a Mopar big block, and b) in general, I try to do some careful research when it comes to working on my beloved 1964 Plymouth Fury — it only makes sense given the modern luxury we are all enjoying relative to information availability.

The downside of the information explosion, however, is the wealth of bad information that one must wade through to find reliable data. As a basic rule, I run most of the information shared on web boards through a healthy filter. Among the golden nuggets of experience lie many landmines of unproven opinion and / or highly inaccurate data albeit passed along by well-intentioned people.

The big block Mopar 440 intake manifold installation research proved to be exactly the case, unfortunately. Worse, it was surprising and frustrating to hear different and sometimes opposing opinions from what I would otherwise have expected to be credible sources. Edelbrock and Fel-Pro, for example, gave me different guidance regarding the number of composite gaskets to use. I am relatively convinced this was due to inexperienced staff answering the phones, especially when it comes to answering Mopar questions. Additionally, one tech was condescending and arrogant on the phone, but it can’t be an easy living answering stupid questions from annoying fellas like me all day long, so I forgive him. Nevertheless, I found it odd. Sealing up an intake manifold is hardly rare. I might also note that the “how-to” books I purchased were so vague on the topic they were useless.


I would like to share something before I go further. I don’t believe there is only one right way of doing anything. If your way differs from my way, and it is effective, it is also the right way. I only mention this in hope that you understand there are many, many variables to problems, and I had to learn that not everything can be solved by being pointed to a certain page of a manual. You have to apply what you read to your situation, and adapt according, based on your circumstances. In this case it is sealing a new aluminum intake onto a 36 year old set of cast iron heads.

Here’s what I am working with:

It is important to note that if any of the above variables change, some or all of the rest of this write-up might not apply and could possibly create issues. For example, if you are using a valley cover instead of a valley pan, it will be a different procedure and will require different parts. My intent here was to get the procedure for my application accurate, not to provide an essay that covers all variables. Perhaps the need to cover multiple applications is the root cause for the vagueness of the procedures I stumbled across.

Parts List

Sealant versus Cement

Edelbrock and Fel-Pro agreed on one thing, and I ignored them both, as do apparently many others. They both said to “cement” the gasket in place. Edelbrock went further, of course recommending their product called Gasgacinch (P/N 9300), although, interestingly, this is called a “sealer” on the can, but clearly looks like a can of glue, a la Permatex High Tack. I just thought I would mention this because it confuses me. Was I only to cement the gasket onto something or did it need some sealant? Are these products also acceptable “sealants” for the intake manifold gaskets? Then why did they use the word cement as a verb? I get confused in a similar manner when people use the word silicone as a verb. Anyway, I don’t think I solved this mystery. But I am not a Chemical Engineer. I am just a guy working on an old car in his garage. I will, however, make a specific recommendation for this application by saying I went with the Permatex® PermaShield™ sealant. The difference between me and the experts is twofold. I am not trying to sell you anything, and I do not have a need to be vague to be sure to cover multiple applications.

Installation Procedure

I broke the installation into two phases. It is important to emphasize the need to complete a mock-up before actually sealing the intake to the heads. For clarity, I’ll call the phases Mock-up and Final Assembly.


The purpose of this phase is to validate the intake-to-cylinder head fit, including the composite gaskets and the valley pan, in a dry assembly. If it did not fit properly, I would have to adjust my installation approach to possible include hiring a quality machine shop to mill the intake. We’ll discuss that a bit later.

Also, as a bonus, I found the mock-up exercise helps shape the metal valley pan, eliminating the need to do so during the final assembly. Enough talking — let’s get started:

  1. Using a straight edge, make a reference line on the cylinder heads, along the top of the intake ports. A Sharpie marker works nicely.
    440 intake manifold sealer
  2. Place your first set of composite runner gaskets on the cylinder head. Line up the ports, and then hold each end in place with a small piece of painter’s tape. Use a good quality roll of tape so it doesn’t stick to the gasket, causing issues when you remove it later. Fortunately, my wife paints furniture as a hobby and has a tape arsenal in our basement, so I “borrowed” some from her.
    440 intake manifold sealer
  3. Lay your valley pan in place, lining up the ports as best as possible for now.
  4. Install your intake end rail tabs and screw / bolts over the top of the valley pan. Snug slightly, just enough to show the valley pan you mean business. Recheck the port alignment and adjust as necessary.
    440 intake manifold sealer
  5. Place your second set of composite runner gaskets on the valley pan. Line up the ports and tape in place as you did with Step 2. Easy on the tape — all you need to do is grab a little corner to hold it in place.
    440 intake manifold sealer
  6. Before you set the intake in place, this is a really good time to check to see if any part of the composite gaskets interfere with the ports. As luck would have it, my gaskets fit perfectly, so I had nothing to do here. In the event there is a poor fit, trim the composite gaskets with an Exacto knife. I would mark the area to be trimmed with a Sharpie and perform the task on a bench, just to be sure nothing falls into the cylinder head.
    440 intake manifold sealer
  7. Set the intake manifold in place by carefully lining it up with the bolt holes without disturbing the gaskets. This could take a little trial and error. Angling one side down first, then gently lowering the other side seemed to work well for me.
  8. The last step of the mock-up phase is to try to install the intake bolts. I got lucky and mine all started relatively easily by hand. On a few corners, I needed to lightly “punch” the manifold with my fist to further shape the valley pan. I was able to twist six bolts all the way in with my fingers. I used a ratcheting wrench to finish threading in the remaining two bolts so I could get a good feel. Anything more than light pressure to get them all the way in would have made me nervous. Remember, we are merely looking for a good fit here.
    440 intake manifold sealer

If you experience any binding when turning the bolts, you may have alignment issues. Don’t proceed without some type of adjustment. You don’t want to strip the bolt heads, or worse, crack the manifold. Here are some suggested remedies to alignment issues:

Final Assembly

The following steps assume you have successfully completed the mock-up phase and did not experience any alignment issues, as was the case with my installation.

A note regarding brackets before you begin. If you plan on reusing or adding any brackets that will attach to the intake manifold bolts (e.g., throttle return, transmission kickdown, coil hold-down, etc.), pause here and gather them up. Understand where each will be located, and exactly which intake manifold bolt or bolts will be leveraged. Have this planned-out in advance and on hand during the procedure. This will avoid having to remove any intake manifold bolt(s) at a later date to install bracket(s).

  1. Clean all surfaces for final installation (cylinder head intake rail, valley pan, and intake manifold).
  2. Lightly smear the PermaShield™ on both sides of all four composite gaskets. Hang them out of the way somewhere and go wash the PermaShield™ off your hands.
  3. Lay one set of the composite gaskets on the cylinder heads, matching up the ports and the bolt holes.
    440 intake manifold sealer
  4. Place a bead of RTV (roughly one-quarter inch thick) on the block where the front and rear of the valley pan will contact it (end rails). Start in the corner, leaving a small gob to overlap with the very corner of the composite gasket, and then apply the RTV across the rail to the other corner, leaving another small gob. I place the bead to the outside of the center line of the rail. I want any excess RTV to fall outside of the engine, not in the valley, when the end rail tabs are installed and tightened.
  5. Carefully set the valley pan in place, over top of the first set of composite gaskets, again lining up the ports and the bolt holes.
  6. Set the end rail tabs in place and start the bolts / screws. Snug the bolts / screws in a bit at a time, working your way from side to side and from front to back, while gently perfecting the alignment of the valley pan. Once the bolts / screws are bottomed, stop for now.
    440 intake manifold sealer
  7. Lay the second set of composite gaskets in place, again lining up the ports and bolt holes.
    440 intake manifold sealer
  8. Play around with the final fitment of the combination of gaskets / valley pan / gaskets, pressing everything down gently to hold it against the head, and making sure everything lines up nicely, particularly the thin strips between each pair of ports. When done, lightly sweep your fingers through the ports to make sure no PermaShield™ is lingering around, blocking any part of the ports.
  9. Get your bolts and, if applicable, any attaching brackets ready. Place a very light coating of PermaShield™ on the bolt threads.
  10. Set the intake manifold in place by carefully lining it up with the bolt holes without disturbing the gaskets. Again, angling one side down first, then gently lowering the other side seemed to work well for me.
  11. Install the bolts and any attaching brackets. Twist the bolts in as far as you can by hand to make sure you have good alignment and the bolts are not binding or stripping. Again, I used a small ratcheting wrench. I liked the feel as I snugged each bolt down. I went at it a little at a time, working in a circular pattern around the inside four bolts, then moving around to the outside bolts. Once all the bolts were bottomed, I torqued to 40 foot pounds in two steps, following the recommended torque sequence.
  12. Tighten the end rail bolts / screws. I found a 9 foot pound torque specification, but to me that’s a bit silly. It was very clear when the end rail bolts / screws were tight when doing so by hand.
  13. Cleanup any RTV that may have spilled out of the end rails and congratulate yourself on a job well done.
    440 intake manifold sealer

Jim Jablonski
Milford, Michigan
contact Jim

Thanks Jim for a clear and comprehensive report!

Thanks also to the members of the 1962 to 1965 Mopar Mail List and Eric at Muscle Motors for technical assistance in correct sealing on installation of this intake.   smile!

Gary H.

March 9, 2014

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