351 Cleveland Manifolds

Mystery of: 180° Dual Plenum, 360° Open Plenum, & 360° Divided Plenum Intake Manifolds. Contributed by a faithful reader.

The biggest difference is the intake runners are divided on the 180. Two go to the Left Bank and two to the Right Bank and you don’t have a scavenging of gas like the 360, fuel is more directed in a 180. This is what gives you a better low end in the 180s. This direction is needed because at low engine speeds gas does not disperse to cylinders well and the 180 kind of divides the fuel. The problem is, after your engine desires more fuel it doesn’t keep up with the demand resulting lower high end RPMs.

When you run a 360° intake, fuel is just dropped into the center and the best cylinder wins. You don’t get a good balance of fuel at low RPMs. Sometimes on Cleveland's (especially if using tall tunnel ram) the car will not perform well at low RPMs because you are losing the intake pulses that help to pull the fuel in to the cylinders. However, once you reach higher RPMs, the vacuum pull from the cylinders draw the mixture in and can divide it more evenly with the 360 intake. There is a lot more fuel to go around in the 360 and results are the ability to achieve increased RPMs. Additionally, the intake ports on a 360 manifold are just about straight down which gives you more of a ram effect.

With the divided 360 it is suppose to give you the best of both worlds, it is split enough to keep the intake pulses good but when you get higher up in the RPMs, the gas can flow between both sides of the intake. A lot of the old ford muscle cars of yester year came that way from the factory. The divided 360 manifold looks just like an Edelbrock Performer but a small 1 inch notch is cut that is about 1/2 inch down in the part that divides the plenum. Consequently, at higher RPMs more fuel can be drawn in to both banks to feed the cylinders. Offenhauser is one company that offers a 360 Divided Plenum Intake Manifold.

TIP: Edelbrock Performer Manifold. The Performer was not strictly built as a performance intake for the 2v. It was developed for the 2v crowd that wanted a 4v and the performance of chunking an iron intake for aluminum.

NOTE: After just purchasing the Edelbrock Performer for my 351C 2V, there is a SPECIAL INSTRUCTIONS section that is nice to know: The port size of the Performer 351-2V and the Performer 351-4V manifold was thoroughly researched and was designed smaller than the head port for several reasons. Although appearing small in size, the legs of this manifold not only flow more than the port in the head, but they also increase the flow in the head. The design of this manifold allows us to use great runner speed which prevents fuel dropout and gives us better fuel and air suspension. This combination is excellent for throttle response, total performance, and provides very favorable emission qualities. As a final note, please do not attempt to match the manifold to the ports. This will not only hurt performance, but it will upset many of the fine features that took months of research and development.

TIP: Weiand X-Celerator and the 351 2v: X-Celerator seems to perform well on race applications but if running on street the X-Celerator is not recommended unless you have a real good gear and high stall converter. In a Street car it will fall on its face, however, if you are driving a race car on the street then it will work. Suggest going with performer you get the use of the 4bbl Carb which will already be an upgrade from the 2v, then put headers with a good exhaust system on. Offenhauser also makes a dual plane for this application.

TIP: TORKER Manifold: Difference between Original TORKER and TORKER II as applied to the 351C 4V. Both manifolds are designed for 351 C.I.D. Ford V8s with 4V Cleveland or Boss 351 heads. Both will not fit under hood of Ford Pantera with stock air cleaner. Both will not fit 351s with 2V heads. Original TORKER has a RPM range of 3500-7500 and is used primarily for drag racing and the TORKER II has a RPM range of 3000-7000 and is more for street applications.

TIP: Cleveland Intake Shootout. In super ford (Oct 1993), there was an intake shootout for the Cleveland. The X-Celerator ranked 3rd. The first was a Holley Dominator, (discontinued) the second was a Blue Thunder, (discontinued). However, the X-Celerator showed better numbers than the Torker.

* NOTE: A recent visitor to the Tips & Tricks section has pointed out that the Blue Thunder is still being manufactured by the originator, AT Francis and is being sold by Pantera East ($325). They can be reached at (727)381-1151.

TIP: Exhaust System Crossover Pipe Installation. The best way to determine where to put the Crossover pipe is to take some spray paint and paint a section about 2-3 feet back from the collector. Start the motor and let it run for just a short time. While motor is running watch to see the point at which the paint doesn't burn off anymore. The paint will discolor further back, but the point at which the paint doesn't burn off is where you want to place your Crossover. Match the size of the Crossover to the size of your existing pipe.

TIP: Cleveland Exhaust Manifolds: The Cleveland Exhaust Manifold is prone to Cracking on the Runners. A Frequent Visitor to this site has located a company that can get you a replacement for your original 351 C 2V Exhaust Manifold. 351 Cleveland 2bbl exhaust manifolds can be found at Perogie Enterprises - New Jersey. The phone number is 609-448-1684, current Point Of Contact is Randy, ask for him. The replacement passenger side manifold in good used condition is $125.00 and an original new Ford piece is $200.00. Not bad prices for aftermarket!!