Intake Manifold Selection and Preparation

In order to make the power we are after we need an intake manifold

The Edelbrock Vic. Jr. single plane intake.
capable of making power past 6500. At this rpm range we could still consider a dual-plane manifold, such as a Weiand Stealth or Edelbrock RPM, however because this engine is being built mainly for dragstrip use, we were not concered with losing some low-end driveability. Therefore we opted for the Edelbrock Victor Jr., pretty much the gold standard when it comes to small block Ford single plane intakes. While we will lose some driveability and torque below 3000 rpm, we can be assured of sqeezing the maximum power available from our head and cam combination.

The Victor Jr. was also an intake we already owned, so it made sense to utilize it rather than blow our budget on a new manifold. Unfortunately however when we took a close look at the intake alignment with our milled World Sr. heads, we noticed the ports on the intake and those on the heads did not line up too well. In other words, if we looked down the intake runners we could see an uneven transition from the intake port to head port. What we could see was the some of the upper head mating surface showing in the intake port. Consequently the floor of the intake port was higher than the floor of the head port, creating a "cliff".

This did not come as a surprise, considering that we had milled the heads 0.030".
We visually examined the port alignment, and also used a coat hanger, with a small bend at the tip, to probe into the port and "feel" the drop between the floor of the ports. Finally we use feeler gauges to measure the gap at the end rails (distance between manifold and block surface).


There is no point in porting heads, or even buying a set of decent flowing heads, if you are going to throw it away on poor intake alignment. The transition you see in the picture not only reduces port volume, it creates poor flow and turbulence.

Oddly enough, on one side of the intake it was the floor transistion which did not line up. However on the opposite side it was the top of the port which was off. Either way we needed to mill the intake to resolve the misalignment.

These steps gave us a good approximation that the intake needed to be
lowered 0.020". This would align the tops of the ports, with a minor cliff remaining at the floor. We would then port match the intake manifold and heads to obtain a perfect alignment. To further confirm 0.020" would suffice, we set the intake on the heads without any gaskets (Fel Pro "Printoseal 1262 gasket is approximately 0.025" when compressed.) Without the gaskets the alignment was very close.

We took our manifold to the PRI show in Sacramento, where DCM had their latest and greatest computer controlled milling and surfacing machine on display. The following steps outline the process of properly aligning an intake on the machining jig and then surfacing the mating surfaces.

Milling the Intake Manifold

The intake is set on the mill and then leveled on the X and Y axis to ensure the cut is made at exactly 90 degrees to the gasket surface.

Interestingly our machinist detected 0.003" twist in the surface near the water passages. The hot coolant causing warpage is the cause. Since were were taking 0.020" off per side, this would set the surfaces true.

Once they figured out how to mount the intake securely, it was simply a matter of setting the parameters in the computer, and sipping coffee while the mill did it's job.

The DCM surfacer cuts aluminum at a blazing fast 12-14 inches per minutes. All it took was two passes and a couple minutes and we were on our way with a corrected manifold.

We did quite a bit of research trying to find a "formula" for milling intake manifolds, and the conclusion is that there is none. It would be nice to say that if you mill the heads 0.030, you mill the intake 0.015 per side. However because most intakes and heads aren't perfectly aligned to begin with, this formula would still leave you with poor alignment.

Another thing to consider is that obtaining perfect alignment is much easier with a single plane manifold because you can actually see the transition on four of the eight runners. On a dual plane intake this is impossible, and you must resort to using a coat hanger to feel the transition. We surmise that most people who have milled heads or decks, or have swapped on an aftermarket manifold or heads, have an alignment problem. It is worth checking out and resolving.
(Final Block Assembly)
Part I Short Block
>Part III Installation
Part IV Dyno Testing

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