Carburator plate adapter differces between square open bore and 4 bores

[GiuG]

Hi there, anyone knows the difference between a open bore plate and the 4 bores one, any performace differences? I'm curious about this, there is a lot of chat about this and prefereces.... Thanks!!!!

 

[Roscobbc]

So looking to use a Quadrajet or spread bore Holley on a 'square' or open plenum single plane manifold? - on a Vette hood clearance might be the primary concern (with the additional depth of the adaptor?

 

[Oneball]

In theory an open one works better at high rpm and the 4 hole type at mid-low rpm.

 

[GiuG]

In theory an open one works better at high rpm and the 4 hole type at mid-low rpm.

Right...sorry for my ignorance, what you mean works better, fuel efficiency or sprint? in high rpm... mid low mean the car start better, idle better?

 

[GiuG]

So looking to use a Quadrajet or spread bore Holley on a 'square' or open plenum single plane manifold? - on a Vette hood clearance might be the primary concern (with the additional depth of the adaptor?

Yeh you're absolutelly right this is the issue, but I wanted to understand why many people suggest the open square one, instead the 4 individual bores that's all, and by the way my air filter has a long stud, that I can cut a bit and there is also the flat version of the open bore adapter... if is going to happen

 

[Oneball]

Right...sorry for my ignorance, what you mean works better, fuel efficiency or sprint? in high rpm... mid low mean the car start better, idle better?

Power/torque. So an open one will produce more power/torque at say 5000rpm than a four hole and the four hole type will produce more power/torque at say 3000rpm than an open one.

But on a standard engine without measuring on a dyno you probably would struggle tell the difference.

 

[GiuG]

Nice, Make sense thank you!!!!