Big block Performer won't fit

[70STOVEBOLT]

Anyone run into this problem before? The four "ears" that stick out for the bolts above the runners (two on each side) make contact with the cylinder head on each side and the manifold will not sit on the block due to this clearance issue. There is not much meat left on the outside of the bottom of the bolt hole so I don't want to take any material off of the manifold. There is a small cast-in "rail" on the heads, and this is what is preventing the manifold from seating properly. Can I grind these four areas enough to get the manifold to fit or will I compromise the head castings?

[geezer#99]

Where’s the pics?

Usually it’s te valve covers interfering.

[70STOVEBOLT]

I don't have pics, but I'm thinking the problem lies within the fact that the heads were milled .020 due to warpage. They were flat milled, not angle milled. Would the intake need to be milled as well? I have read blogs where people say yes and no.

[geezer#99]

That’s possible.
Easy to check.
Put a small flashlight in the valley and set the intake on with no gaskets.
Easy to see if the angles are off or where there is interference.

[70STOVEBOLT]

Jim, thanks for the replies, I will check that and post what I find.

[70STOVEBOLT]

Here is a pic of the manifold (not mine but the same p/n) you can see the ears I am talking about above the port separator wall. These protrusions interfere with the cylinder heads. You can see there is not much material to remove without compromising the strength of the bolt hole. I will try to find a pic of a big block head for reference as well.

[geezer#99]

Like I said, those ears usually interfere on the valve covers.

[GASoline71]

If you had the heads shaved or the block decked, there is an off chance that it could cause interference. You could have the machine shop shave some material off of the mating surface of the intake manifold too.

Gary

[toolboxchev]

I flat milled my SBC heads, yes the intake needed to be milled yet I was able to get away with it, without milling. You can tell by the distance on the china wall.

[70STOVEBOLT]

I'm not worried about the angle, as the bolts threaded in by hand easily, I just need to get the "ears" past the rail on the cylinder head. It appears that it will seal ok, just can't get it down into position, and I am not going to remove the heads, as I just got them back on. I don't really want to grind on the heads as I don't want to risk getting any metal inside the engine, but it looks like that will be my only choice. I will run the stock iron intake for now and if I have to grind on the heads, I will do it with the engine together to avoid getting any metal inside the engine.

[70STOVEBOLT]

I don't mean to offend anyone, but I am looking for real world experience with this particular issue, not opinions. Not trying to be an arse but I have searched this website and many others and I believe someone must have run into this issue before.

[geezer#99]

Mask off the valley and the head ports and then spread some grease around the area on the rail you need to work on and use a file to clearance it.
The grease will catch any fillings.

[70STOVEBOLT]

Originally Posted by geezer#99

Mask off the valley and the head ports and then spread some grease around the area on the rail you need to work on and use a file to clearance it.
The grease will catch any fillings.

That's a good idea, I might try that. Thank you!

[68c10owner]

It sounds like you are using a later engine, or possibly later heads. What year is the engine as and do you have the casting number of the heads?

You can machine the intake slightly. I wouldn't do a flat grind. I would grind it at a angle. But before you do that let's find bbn out what heads you have

[95 S_Trucker]

If your heads don't use the upper bolt holes above the intake ports, you can cut the ears the whole way off.

I am aware of the lip on the heads where the valve cover seals. Is that what is hitting?

We need pics of your heads, or the casting number of your heads, so all of us here can see what you are seeing.

What engine/heads do you have? Mark IV, Gen V, Gen VI?

Make sure your ports match.

[70STOVEBOLT]

It's a 1972 counter exchange replacement 402, with 3993820 heads. All 16 intake bolts are required, and yes, the cast-in rail on the heads is what the ears on the intake are hitting. The ports match. The intake is a 2161 Edelbrock Performer 2-0 which is designed for the Mark IV big block. There are impressions in the lip on the heads at the points where the intake hits, I assume for clearance for the stock iron intake, but they are not deep enough for the aluminum intake to clear. I have not had a chance to work on it yet, but I will most likely take geezer99's advice and use a file to make the clearance. Thanks for the replies.

[70STOVEBOLT]

I used a carbide bit on my air die grinder and clearanced the heads just enough to get it to fit. Thanks again to all who responded.

[geezer#99]

Excellent!
Ain’t it always the little details that drive you crazy!!

[70STOVEBOLT]

Originally Posted by geezer#99

Excellent!
Ain’t it always the little details that drive you crazy!!

Yes, and time consuming.