Understanding intake manifold principles.

  • Thread starter Bret Williamson
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In summary, Bret W. found that the cross-over pipe designed to balance the pressure in the intake runners was originally intended to reduce the syncronization problem. He is planning to build a dual-carb manifold using more modern (60's) carburettors.
  • #1
Bret Williamson
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Hi there, hope someone is able to help me. I am trying to find some info on early intake manifold designs, for Ford 4 cylinder engines, otherwise known as the T-, A- and B- engines. These engines came standard with two intake manifold inlets, and 4 exhaust manifold outlets cast into the block.
I have found lots of pictures of after-market dual-carburettor manifolds. These used dual intake runners, with two general systems. In the first system, the carburettors mounted on a common plenum, which then opened into the intake runners. In the second system, the carburettors were mounted at the top of the intake runner, with a cross-over pipe linking the intake runners.
Does anyone know the theory behind this cross-over pipe, or seeming balancing of the intake runners? Is one more effective than the other? Can anyone point me to a source that might explain the principles?
Cheers
Bret W.
 
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  • #2
Sounds like it's just a balancing pipe, equalising pressure in the runners to ensure that the cylinders are inducing the same quantity, and mixture, of inlet charge.

Do you have any pictures of the arrangements?
 
  • #3
Don't know the Ford engines, but I've dealt with separate plenum systems on other engines.
It was a real headache to syncronize the carbs.

Perhaps the crossover was intended to reduce the syncronization problem as brewnog suggests.
 
  • #4
I've got a Ford engine (1960s design) using two twin-choke carbs, so there is a plenum for each pair of cylinders. As a result, cylinders 1 & 2, and cylinders 3 & 4 are balanced, but it can be quite a pain to balance the two pairs. The original carburettor on the engine had a single plenum, and single carb feeding all four cylinders on a common manifold. Much easier to set up, but not nearly the same flow.
 
  • #5
I think you are on to something there brewnog. I seem to remember reading something similar about crossover pipes in exhaust systems blancing the pressure.

I am planning to build a dual-carb manifold, but thought i would try to understand the principles before i added anything to the design unnecessarily! Like i said, a lot of the aftermarket stuff was twin-carb items, most developed in the 30's, 40's and 50's, when there wasn't a wide range of different flow-rate carbs to choose from, like we have today. So, those clever guys realising that the more air/fuel mix available, the more potential energy, started adding multiple carbs.
So, my aim is to emulate that basic idea, but using more modern (60's) carburettors.
 
  • #6
Mmm, twin choke Weber DCOEs maybe?

:smile:
 

Related to Understanding intake manifold principles.

What is an intake manifold?

An intake manifold is a component in an internal combustion engine that is responsible for delivering air and fuel to the engine's cylinders. It is usually made of metal or plastic and is connected to the engine's throttle body.

How does an intake manifold work?

The intake manifold works by collecting air and fuel from the carburetor or fuel injectors and distributing it evenly to each cylinder in the engine. This helps to ensure that each cylinder receives the correct amount of air and fuel for combustion.

What are the different types of intake manifolds?

There are several types of intake manifolds, including single plane, dual plane, and tunnel ram. Single plane manifolds have a single, large plenum that feeds all the cylinders equally. Dual plane manifolds have two separate plenums, one for each bank of cylinders. Tunnel ram manifolds are designed for high-performance engines and have long, straight runners that help increase air flow.

Why is the design of an intake manifold important?

The design of an intake manifold is important because it directly affects the performance of the engine. The length and shape of the runners, as well as the size of the plenum, can impact the engine's power, torque, and overall efficiency.

Can an intake manifold be modified for better performance?

Yes, an intake manifold can be modified for better performance. This can include changing the length or shape of the runners, increasing the size of the plenum, or adding features like velocity stacks. However, it is important to carefully consider the engine's specific needs and to make modifications in a way that will not negatively impact the engine's performance.

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