Installation of my Edelbrock intake was messy. After torquing, we noticed the front seal was blown out from underneath. We removed the intake, cleaned all the dried sealant off the pan, and reinstalled. It started blowing out again. Next time, we removed the intake valley pan completely, cleaned the block, seals, both sides of the pan, and set the seals in silicone. We waited several hours, then reinstalled the pan and intake. It tried to blow again, but I got a putty knife and pushed the seal under the intake. Slow torquing while pushing against the seal with some blunt object seemed to do the trick, finally.

I read the Edelbrock literature to put the sealant around the ports, and four corners of block, and the seal itself. First few times I was kinda liberal, but after having to clean it up so much and sticking exactly to what it said to do 'cause of the problems we'd been having, we didn't go around the water ports. After looking in Tom Monroe's book, it said to seal around them too.

Sorry for chasing my tail to get to the question, but how likely am I going to have a problem here and how will the problem present itself?

 

The manifold will not fit properly if the heads and block have been machined. The manifold must be machined to match. The front gasket is frequently too big to fit the gap after engine machine work and a bead of silicone is used instead. The manifold can be machined for the seal spacing but most people just use silicone instead. Torquing an intake down that does not fit the block can cause intake leaks and possibly damage the manifold.

 

Ok, it seemed to want to blow only at the front, and to right mainly a bit on left side too. I've got it torqued to 25ft-lbs. I've laid silicone too. If I have vacuum leaks that will be apparent how?

As to the water ports, if water blows by then where will it go? Into the valley or visible leak around the intake?

The machining was supposed to be very minimal. Have no further detail than that, maybe he used the term "polish it up some" nothing more.

 

Do these intakes have a specific torque pattern that should be followed to avoid this? Sometimes an improper torque pattern creates this problem.

 

yes. i followed the sequence exactly, going in 5ft-lb increments, starting at 10 up to 25.

I inserted a putty knife between the valley pan gasket and the seal-- kinda pushed it in under the valley pan by the way it felt. maybe the valley pan gasket flexed and caught the seal. The valley pan was flat and had to be sort of pushed into place to fold the sides in under the alignment pins. It remained under some tension like that.

As Torque1st states, the milling could explain this. I had read about silicone for a seal, but edelbrock is the warrantying party so I wanted to follow their instructions completely.

 

There are no water ports in a 351C/M/400 intake.