question on intake fit

[Boiler Ben]

I need some advice on fitting the intake manifold.  I have new Edelbrock heads and new Edelbrock intake.  The heads are installed and torqued.  I've measured for pushrods and ordered them.  I placed the intake gaskets to test the fit and lowered the intake carefully, making sure the gaskets stayed in the right spot.  The bolt holes are pretty much centered.  I haven't installed the distributor yet but just eyeballing it, it looks centered.  I can't get a 0.010" feeler in anywhere along the gasket interface so it seems pretty much ideal there.  The front wall dimension is about 0.175" and the rear wall is about 0.142".

The problem, as you can see in the photos, is that the heads stand proud about 0.062".  The two surfaces are parallel, just offset.  One corner is better than the others so maybe there is some more adjustment to make but there is still a significant offset.

[1964Fastback]

It doesn't look like you have the cork gaskets in place in the front and back.  Have you tried it with those installed?  On mine (factory iron heads, 3x2 intake and also the original iron 4 bbl), I had to cut the tabs off the ends of the cork gaskets or they were too long and wouldn't lay flat (Fel-pro BTW).  Then they fit pretty good.  Glued them in place with weatherstrip adhesive with a blob of RTV.

Pat

[allrightmike]

You didn't mention the thickness of the intake gaskets but I will suggest thicker gaskets which are available. This will bring the intake up in relation to the heads. As for the cork end gaskets, I would suggest using a bead of sealer if you have time to let it cure.

[Stangman]

I agree use thicker gaskets and no cork seals on china walls.

[blykins]

No cork...

Thicker gaskets.

This is the second post where I've seen a Performer RPM intake sit low.  Is this the same user, or is Edelbrock sleeping on the job?

[Boiler Ben]

This is the first I’ve mentioned it so maybe someone else has the same problem.  I bought the heads, intake, and gaskets from Edelbrock all at the same time, maybe 6 months ago.  The gaskets are Edelbrock 7224 and measure 0.064” uncompressed.  I see some thicker gaskets from Cometic up to 0.125” compressed thickness.  That difference is about what I need to make up, but with all the angles involved, I’m not sure if that’s what the result would be.  Maybe I should try the 0.094” compressed thickness ones?  As I mentioned, the bolt holes are more or less centered right now. 

[blykins]

This is the first I’ve mentioned it so maybe someone else has the same problem.  I bought the heads, intake, and gaskets from Edelbrock all at the same time, maybe 6 months ago.  The gaskets are Edelbrock 7224 and measure 0.064” uncompressed.  I see some thicker gaskets from Cometic up to 0.125” compressed thickness.  That difference is about what I need to make up, but with all the angles involved, I’m not sure if that’s what the result would be.  Maybe I should try the 0.094” compressed thickness ones?  As I mentioned, the bolt holes are more or less centered right now.

Do you have a way to look down into the plenum and see if the ports line up?

I'd go with a gasket thickness that you need to make up the difference.  If it's .060" down below the head and you already have a .060" gasket in there, then I'd try a .120" gasket. 

Be ready to hone your silicone-bead-laying skills for the china walls. 

[My427stang]

Feeler gauges on 4 corners can tell how much more you need after you check ports lkike Brent said. 

However, I saw another post where someone ran into the same thing.  I wonder if Edelbrock had a machining issue. Deep intake fit means tall heads, tall deck or small intake and if you have new parts on a block that is likely decked, seems like somethying isn't right.  We usually fight the opposite.

That being said, nothing wrong with a thick gasket if that's what you need. 

[Boiler Ben]

I tried working a small mirror inside and saw one edge of the port but couldn’t really draw any conclusions about the port alignment. I think I’ll set it up as best I can and get a good measurement for a new gasket. That china wall gap will be just shy of 1/4”.

[blykins]

I tried working a small mirror inside and saw one edge of the port but couldn’t really draw any conclusions about the port alignment. I think I’ll set it up as best I can and get a good measurement for a new gasket. That china wall gap will be just shy of 1/4”.

1/4" is not an issue.  Get some Dow Corning 732 and lay a thick bead down. 

[pbf777]

      This problem your experiencing of the valve cover rail surface seems to have become a rather common problem with Edelbrock.   

      But before you run off and attempt to address this, first, utilizing a straight edge and a pair of calipers, or a reasonable measuring device, providing references on both surface faces, establish the primary concern, that of the relationship between the intake manifold to cylinder head port openings.  Then is the relationship to the bolt holes and what processes might be required here, involving what compromises.  Lastly in the hierarchy is the concern for the valve cover rail alignment.   

      Scott.
       

[kcoffield]

Rather than valve cover rail or modest port misalignment, another, or perhaps the bigger issue is how well the mounting holes line up. Assuming the heads and intake are at or near OE spec dimension, is the reason the valve cover rails are low due to rail height merely being machined too low or has more/incorrect amount of material been machined from the intake faces? Or was the intake intended to use a .125 gasket (seems unlikely). You do have a standard thickness head gasket installed....correct?

Increasing the intake gasket thickness .062 will raise the VC rail the same, but it will also move the mounting hole locations on the intake in respect to the head, somewhere between .062 and .062/sqrt2 depending upon the angle of the hole. A vertical hole (45 degrees to head face) won't change at all.

Unless the mounting holes are grossly over size, that is likely greater than the radial clearance of the intake mounting hole to the bolt, so that means your intake could land on the sides of the bolts before it seats on the gasket..........very bad......no seal.

Before you buy a .125" intake gasket, see if you can install mounting bolts with your present gasket, and then do same with two .062 gaskets.

Best,
Kelly

[Boiler Ben]

I’ve been concerned about bolt hole alignment too. My thought is to remove the intake and take some measurement to determine how the bolt holes relate to port alignment. Then refit it using the gaskets I have and try to figure out exactly what gasket thickness would align the VC. Maybe I can then try to shim the intake on the china walls to get the VC aligned and then see how the bolt holes look. I’ll need to sketch out this square root of 2 idea to see what that looks like.

I may need to end up with some compromises in each area. How bad is it to open up the bolt clearance holes in the intake?  I haven’t received pushrods yet but once they show up, I need to see how they fit too.

[Boiler Ben]

So I’ve made some more measurements and am trying to make sense of it. The ports on heads are all the same. It’s the manifold that seems to be off.  The ports in the manifold are slightly narrower but at least seem centered front to back.  But the vertical position of the ports is different on drivers side compared to passenger side.

Also, I’ve now used the distributor to align things and there is less adjustment possible because of this.  The amount of the VC mismatch is different left to right.  It almost looks like I could use a 0.094” gasket on the passenger side and a 0.125” gasket on the drivers side.  Any chance Cometic would sell me this combo?

I think doing this would be good for drivers side port alignment but passenger side port alignment would be off ~0.074”.  The VC should be OK all around.  Need to double check bolt clearance.

[My427stang]

As said before, another old forum member ran into this too and got the intake replaced . May want to give Edelbrock a call to see if they have seen a narrow manifold and could track timing to yours