Mounting LD340 using thicker intake gaskets....what about the rails?

[kawahonda]

When I initially begun mounting the LD340, I discovered that the intake has been previously milled due to the left and right gap. I calculated that a .120" gasket should fit perfectly. Luckily I was able to find a set on Summit.

Now that I have the intake sitting on the .120" gasket, I'm measuring a .265-.280" gap on the front and end rails (without intake torqued down).

So I'm figuring that I'd probably want about 5/16" of gasket material for the end rails. I've been unsuccessful in finding 5/16" cork gasket material other than $50 for a sheet of it online. Trying to figure out what my options here should be.

I have some felpro and some other branded gaskets that I can stack together in order to create 5/16", but I'd prefer to not stack if possible.

Options or recommendations here?

[Rich G.]

Just use a good type of  silicone sealer on the ends .

[kawahonda]

Is 5/16" a little much though to rely on RTV alone? Just curious...

[Brads70]

  "Right Stuff" works really well but harder to remove so I've read, if it comes to that?  I've never had to remove any of it before though...


https://www.permatex.com/product-category/gasketing/the-right-stuff-gasket-makers/

[kawahonda]

I remembered I bought a can of that stuff for about $40. Got home and did some research and learned that the right stuff is basically Ultra Black, but with faster setup time so I returned it, thinking I wouldn't need to use it. I got the impression that it's more ideal for a mechanic that needs faster setup and to keep moving.

I have Ultra Grey and Ultra Black currently. Permatex seems to recommend Ultra grey for intake areas, and black for anything else?

But maybe there's more to it? If I did create a gasket with RTV only, is there a benefit to The Right Stuff over Ultra black?

One thing I'm wondering is that it would likely be better to have it 100% RTV vs RTV with a single cork as using a single cork there would be no compression.

I really wish I had less than a .25" gap because I would simply just use any standard Chrysler cork with some RTV. But my gap is .27".

I don't mean to over think it, but I put a lot of work into fitment and getting specialty gaskets so I want to make sure it's sealed properly!

[Brads70]

I'd say you will be fine. I used the grey on my engine build with no leaks. Can't remember what the end gap was but....?   I 'd lay a 3/8"+ bead on there let it skim up then go. A little more on the corners maybe .

  If your concerned it will blow out , maybe on the bottom ends of the intake drill and tap for a few small screws/ set screws, along the rail to hold it in place?

[kawahonda]

Thanks for the responses. I used some Grey "The Right Stuff". Built a big-ass bead. Set it down, lifted it back up (carefully). Added some more to certain spots, and set it down again. Pretty sure it's very well sealed, especially after torqued. I smoothed it around the outside as well, and added some more from the outside to the corners to assure.

While my LD340 has be milled some, I'd be tempted to use this method almost always and ditch the corks for a factory rebuild. I can see why the corks can cause problems--when the gap isn't as small as it should be. In my case, the gap was pretty large on the end rails.

Using the corks requires you to dry-fit it for sure!

[Scooter]

When I rebuilt the BB 390FE in my Fairlane I did not take the advise of my engine builder friend who advised a good size bead of right stuff at the front and rear of the intake. I used the cork with a thin layer of RTV. Over the next few years I got to watch both front and back slowly begin to sweat out oil and make a mess. On a FE the pushrods go through the intake, so replacing the intake seal requires removal of the valvetrain as well. I ignored the mess until I could not stand looking at it and wiping my motor down. Did it a few months back... good sized bead of right stuff.... all good now. 

[kawahonda]

Awesome! Yeah, I don't even remember how exactly I did my FE 390 years ago. Yep, weird intake design for sure! Can't remember what I did exactly, but yep, The Right Stuff is kinda hard to say no to.

Just having that applicator can makes the job so fast and easy too.

Here's some pics from my install.

[Scooter]

^^ Looks good from here.

I give that front and back corner where the intake meets the head and around those water passages special attention.

On the FE the oil return from the head is righ there so you need to be careful as well.

Rather have a lil too much goop than not enough.

[Mrbill426]

@kawahonda  Just curious... how is the manifold sealing holding up?

[kawahonda]

Embarrasingly, I haven't even ran the engine yet. It's complete on the stand, dressed in ma-mopar paint and looks pretty much stock as a rock.

I've gotten too many recommendations that I shouldn't just stick it into the car, but I should pay to have it placed on a run stand. I figured this was sound advice because I do not want any leaks in the new motor.

Problem is, I started to remodel the kitchen and am mostly finished with that, but I haven't been calling around figuring out where to take it, and "how" to take it without scratching it up. It's all painted and looks like a factory 340 with an LD340.

I have been thinking about this more recently that I need to get this into the car, but I'm totally a novice and not sure where I should take it in Boise, or how it should be transported in a safe manner. Lifting it and placing it down is going to scratch it up.