It’s no secret that when increasing the horsepower in the two-bolt main small-block Ford engines, things tend to move around a bit. One of those issues is main cap walk, as a result, we get a very slight shifting or sliding between the main bearing caps and block. While this issue is not limited to the small-block Ford engines, they will be our primary focus.
Canton Racing Products has a wide selection of supplemental performance parts to help reduce or eliminate this issue.
Why Does It Happen?
As we increase horsepower, it follows that we are also increasing the stresses and pressure on components. Some of these stresses are twisting and flexing of the crankshaft and block. This puts a heavy load on the main caps. It creates a very real potential for the caps to walk or shift in the block registers.
Some of the possible consequences of cap walk are metal transfer or scuffing of the mating surfaces between the main cap and block. Another one you might not associate with or even realize could be happening is oil flow issues.
As the cap deflects and shifts, the bearing surface area can become distorted. This could restrict, or allow oil to unnecessarily bleed off. We all know the negative effects of the lack of oil, but extra oil escaping is not good either. This bleed off is unnecessary windage and something we will touch on later. However you look at the situation, catastrophic failure is at the door if left unaddressed.
How Do We Prevent Cap Walk?
There are a few ways to reduce or eliminate cap walk on the two-bolt blocks. A couple of the easiest for the SBF would be installing a main cap support (a.k.a. main girdle) over the caps, linking them together, and installing high-quality fasteners.
Main Girdle
What is a Main Girdle? This component is a thick metal brace that ties all the main caps together. It sits on top of the caps, under the engine. This creates a structural cage of sorts, relying on one another to keep them all rigidly aligned. In the case of the Canton Main Supports, they additionally offer ARP fasteners and a direct mounting point for their windage trays.
Windage Trays
Windage is a real issue affecting crankshaft rotation, especially at higher RPM. With the pistons reciprocating at lightning speed, the air and oil in the crankcase are violently shifting. This motion creates turbulence that can displace the engine oil in the pan, potentially splashing onto the rotating crankshaft.
Think of this splashing on the crank like trying to run in waist-deep water; you can move, but the resistance is greater than if the water were only ankle deep. By reducing the amount of oil on the crank surface it minimizes unnecessary resistance. That is how windage affects the crank spinning freely.
By adding a Windage Tray under the crankshaft, we can limit the oil splashing in the pan from motion or turbulence. However, for a small-block Ford, a main girdle and windage tray were an either-or option, until Canton developed a windage tray specifically for use with the main girdle.
Running a girdle and windage tray is a great idea. However, it is going to burn some real estate in your pan. This will usually lead to an aftermarket oil pan option.
What Are The Options?
Canton Racing Products is one resource that is worth contacting. They have girdles, fasteners (ARP), windage trays, oil pick-up tubes and pans that are designed to work in unison. They even have girdle options designed with extra clearance to work with stroked crankshafts.
The Canton tech line is top-notch and will walk you through all the options for your application. As an added bonus, their parts are made in the USA. What was once a piecemeal, either-or arrangement of parts, is now a well-engineered, cohesive system that allows you to take full advantage of modern components and their full power potential with a stock 302 block.
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