Problem with Edelbrock Performer Intake on 340!!

[jmartin99]

I am putting together a '72 Challenger for a friend. It has a 340 and he purchased Edelbrock Performer Aluminum heads and a Performer RPM AirGap intake. While assembling it I went to install the A/C Compressor on the motor and have run across a big problem. The heater hose nipple only fits in the intake on the drivers side of the water neck. With the nipple in that hole in the intake, the rear bracket for the compressor hits the nipple before the bracket gets far enough back to put the bolt through it into the intake! There is another hole on the passenger side of the water neck but it is only 1/4" NPT not 3/8"NPT like the nipple takes.

Has anyone else ever run into this problem?   

What did you do?

I am tempted to drill out the 1/4" NPT hole and tap it to 3/8" NPT. Anyone else ever try this? How difficult was it?

Jeff 

[Road_Runner]

Sorry, no help here, but while I was struggling to get bypass & radiator hoses swapped out on the Barracuda a couple weeks agao I was looking at this and other issues with how the standard A/C mounts to the engine block & intake and it made me concerned that many of the performance manifolds may not work with the stock A/C setup.  Specifically, some of the higher performance aluminum manifolds don't appear to have the mount points and all the fittings drilled. So I'm going to be following along here to see what kind of advice you get. 

Later, jim

[the_engineers]

You should be able to drill out and re-tap.  How substantial is the boss around the current hole?  Got a pic?

[jmartin99]

The boss is plenty big enough. I will post a pic in the next day or so.

I went to Rural King tonight to see what the price for the tap was because I only have 1/8" NPT and 1/4" NPT taps. The price was not too bad ($8.49) but the real problem is a 37/64" hole is required before you tap it. They had a 37/64" drill bit but it was gold!!! $45.95!!!  I am going to see if a friend has the tap and drill bit I can borrow.

I just find it really hard to believe that the Edelbrock Manifold is not like the original when it comes to the pipe thread holes! The original heater hose nipple which is 3/8" NPT was on the passenger side of the water outlet and the Edelbrock mainfold has 1/4" NPT hole on the passenger side and 3/8" NPT hole on the drivers side. There is no hole at all on the drivers side of the original. It is also funny because the threaded boss is there for the bracket which comes off the side of the compressor and attaches to the top of the manifold. You just can't get the bracket where it needs to be with the nipple in the hole on the drivers side. 

Jeff