Intake Manifold Gaskets

[CincoBravo]

Getting ready to replace intake manifold gaskets. I have the gaskets from Felpro. I watched a video today by Early Nashville Bronco and he said to not use the gaskets at the front and rear of the intake manifold but to instead just use a generous amount of RTV. He said those front and rear gaskets don't work. Does anyone agree with him? Should I toss them and just use RTV?

 

[ptwist]

Just did my intake about 3 months ago. I spoke with Edelbrock tech and that was the advise I received. My intake was setting about .2 in. away from the engine block at that location and I had to check to be sure that was acceptable/normal. They had no idea and didn't think anyone had ever asked that question but thought it would be ok. Regardless they said to seal it with RTV.

 

[mattyq17]

Yes RTV for the front and back rails, do not use the cork or plastic pieces the gaskets come with. 1/4" bead should work fine.

Which Felpro gaskets did you get? If they are the 1250's people have had issues with those not holding up, the 1250-S3 (steel reinforced or something like that) are the ones you want.

 

[CincoBravo]

Thanks

Thanks for the feedback! It's my weekend project so that was a big help.

 

[OX1]

I drop the intake on with the gaskets, not bolted down, to see what kind of
gap I am dealing with before putting my bead of RTV on.

 

[B RON CO]

Hi, I like to use 4 pieces of 5/16 threaded rod as a guide to hold the long gaskets in place and guide the intake manifold down. Then I get the rest of the bolts started before removing the threaded rods and installing the rest of the bolts.
Also follow the bolt tightening sequence, from the center out.
Good luck

 

[75brnco]

x2 on the 1250's being garbage

 

[cs_88]

Hi, I like to use 4 pieces of 5/16 threaded rod as a guide to hold the long gaskets in place and guide the intake manifold down. Then I get the rest of the bolts started before removing the threaded rods and installing the rest of the bolts.
Also follow the bolt tightening sequence, from the center out.
Good luck

Agreed.
You can get 3" lengths of rod at Lowes.

 

[DirtDonk]

...He said those front and rear gaskets don't work.

Just to be clear, those gaskets "can" work very well. Especially when there has been no other machining of the engine to mess with the gaps.
They're just more finicky and more subject to issues when circumstances arise...
I've never personally experienced a problem with them, or with any that I was familiar with. But for the last 40 or so years it's been accepted practice to replace those end seals, whether they were cork or rubber, with a bead of sealer instead.
In fact I bet the rubber ones were brought in to replace the cork ones when so many people had problems with them. Different material, and they had side flanges that were supposed to hold them in place so they did not squeeze out when you torqued down the intake.
Guess they weren't much better at it after all though.%)

The end seals were the original design and worked for many years, but add whatever inconsistencies, additional machining to heads and block that could skew the gaps, or just plain mistakes in installation (very common back in the day) and you had a recipe for leaks.
Enough leaks with the seals, and the ease and acceptance of silicone sealers, and it's pretty much universal now for people to use sealer instead.

So I'm not trying to talk you out of using sealer. Just pointing out why seals are still included in the kits. Sealer seems the best way to do it for most, and does work well when you do it right and don't knock the bead around too much during the manifold installation. That can happen too, just like using the end seals.
But sealer is more forgiving of that I think. And I'm sure you can find some pretty good videos of that type of installation as well.

Good luck!

Paul

 

[blubuckaroo]

I used the cork and rubber end seals successfully for years. Then in the late '70s, RTV hit the market. Customers didn't know how to or when to use the stuff. When you put it on gasket surfaces where the gasket isn't held in place somehow, it has a tendency to lubricate the gasket and spit it right out.
Some of the gaskets you don't want to use it on are pan, valley cover, valve cover, and these intake manifold end gaskets. Gaskets like these work better with an adhesive type sealer like Gaskesinch or Indian Head. It would even be better to install the gasket dry rather than use RTV here.
As far as a cork end gasket restricting the clamping force on the intake manifold gasket, that's pretty hard to believe. Even with the light 18 ft. lb. intake manifold bolt torque.

 

[savage]

I've installed the end seals ,dry, and used adhesive and have used just RTV. Only problem I've had using RTV was if for some resume you need to take the intake off ,it can be a bitch to pull off. I do use four long bolts ,that I cut the heads off , and installed them on four corners to keep the intake from moving, that way I can install all the other intake bolts, then I remove the ones at the four corners, and replace them with the remaining intake bolts.

 

[CincoBravo]

Excellent info from all. Thanks! I especially like the threaded rod for guides suggestion. Looks like I'm on my way to the hardware store!

 

[CincoBravo]

Which Felpro gaskets did you get? If they are the 1250's people have had issues with those not holding up, the 1250-S3 (steel reinforced or something like that) are the ones you want.

I have pn MS 90361

 

[Steve83]

...just use a generous amount of RTV. He said those front and rear gaskets don't work.

The original end gaskets are molded rubber, and they work VERY well. But they're hard to find, and sets that include them (E9AZ-9433-A) are expensive, and include crappy "main" gaskets.
https://www.ebay.com/itm/183172740084

Use modern graphite gaskets along the sides (like Victor MS15202W). If you can't find the rubber end seals, just lay a continuous bead of sealant along that edge. I prefer RightStuff.


(phone app link)

You can get 3" lengths of rod at Lowes.

...or just cut the heads off some long bolts.

 

[CincoBravo]

gracias!