The wall of the runner in...
The wall of the runner in this shot extends wider than the intake portof the manifold--exactly what you do not want. By measuring yourdimensions from one good port wall, you can mark on the manifold howmuch material you need to add, either with epoxy or by welding inaluminum.
Obviously, the best thing is to use the actual block you plan to use andhave it already decked to the correct height. If you go this route,leave 0.002-inch extra material on the deck and then shave it off laterto remove any scratches.
Likewise, you will also need to put shims on the head to duplicate thethickness of the intake gaskets. Ronald does not recommend using theactual intake gasket because it can interfere with your ability todetermine where the ports do and do not match up. For example, if thegaskets are smaller than the port, it can be hard to see the edges ofthe intake port.
A scribe line (arrow) marks...
A scribe line (arrow) marks our good wall. This line will be ourbaseline for all the other measurements for the rest of the ports.
"Intake gaskets normally come in various thicknesses, so even though youneed to decide what thickness you plan to run, you can also use thatadjustability to help line up the manifold," Ronald adds. "For mostheads, they offer gaskets with 0.030-, 0.045-, 0.060-, 0.090-, and0.120-inch thicknesses. We usually start out with a 0.060. So say thefloor of the manifold is hanging down. You can thicken up the gasket tobring the manifold up and raise the floor of the runner to match theintake port instead of trying to add material to the manifold."
Line Up and Measure Down
Once the heads are bolted in place at the proper height and shimmed forthe head gaskets, paint the flanges of the manifold with machinist's dyeand place the manifold between the heads. You can use the bolt holes forinitially lining things up, but this will be the last time you will payany attention to them. The priority is the ports: If the bolt holes areout of line after you complete the port match, you can mill slots so themanifold will bolt into place.
Jonathan Leagon uses his baseline...
Jonathan Leagon uses his baseline wall to find the dimensions for therest of the ports. By going from the head directly to the manifold youcan get a very accurate map of how the manifold runners need to beadjusted.
Make sure the manifold is all the way down (you may want to hit the topof it with the flat of your hand to make sure it is properly seated) andcheck to make sure the manifold end rails have some clearance underthem. If they hit the block, it will keep the manifold from seatingproperly. The solution is to either go with a thicker intake gasket ormachine the end rails down some on a mill.
First, check that you have either the floor or ceiling of the port matchup on either bank. With luck, you will get either the floor or ceilingto match up properly on both sides. If not, you can try different intakegasket sizes to move the manifold up (thicker gasket) or down (thinner)in relation to the heads. Because most of the air/fuel charge flowsalong the ceiling of the port, Leagon's usually prefers the roofs matchup.
Next, slide the manifold forward and backward, checking to see where thecommon walls match up. Common walls are the narrow walls that separateintake ports that run side-by-side. The other wall of the port isgenerally called the pushrod wall, because it is the side closest to thepushrod. The common walls are straighter and generally easier to see andalign. Slide the manifold until you get the maximum number of commonwalls to line up. The best case is all four common walls line up on bothsides; the worst case is only one side of one common wall will line upat any one time. This is OK, too. Pick one wall as your starting pointon each side, make a note of exactly which wall you are looking at, andpull the manifold back off the engine.