Thread: BBC heads. Oval, rectangle port. What's the deal?

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I know there is a long answer to this question but I am just looking for some basic facts or opinions.

I look at for sale ads and they often will say "oval" ports, or "rectangle" ports.
I have also read that the oval ports are not really oval or the rectangle ports are kind of oval (or something like that).

I'm confused. (However this is a normal condition for me so dont be alarmed)

Is one better than the other?

Does anyone have pics showing the difference in the port shapes?

Thanks again in advance. You guys are a great source of information.

They are both good for "their" application.I believe the oval ports are great for low end torque motors and the rectangle ports are great for motors that are built for the top end.

no there are small ovals and big ovals and rect port are very much the shape of a[] and the ovals are ovals they work good for the street and good power can be made with them a good street/strip build heads. to rect is a good working head for bigger cid and hi rpm builds both work i used many

Thanks guys.

Any pictures to help make a positive ID?

hard to mix them up theres casting number that can be look up as well as the rect port is about1.820by2.54 and is [] the o port is 1.820 by 2.050 and is o here is a rect port

These are mild ported ovals off ZZ502 ............

Kitz

kit them are not realy O port that s the edlbrock/ GM 502zz head

Pat these are the GM heads that come with the ZZ502. Are you saying they are made by Edelbrock?

Kitz

Originally Posted by kitz

Pat these are the GM heads that come with the ZZ502. Are you saying they are made by Edelbrock?

Kitz

yes i know what they are i built two engines using them heads a dual turbo 540 that started life as a zz502 and a all new McCarthy Performance better built then GM 502ZZ i built. one 525 tall deck that i used the edelbrocks not much dif

I know what you mean Maddog, I stared at the ports on the Gen VI engine I picked up a few weeks ago and couldn't figure out if they were oval or rectangular. They were sort of in between in appearance. But I finally figured out that if they had any roundness to their shape they are oval, and if they are very boxy they are rectangular. At least that is what I came up with, so I guess mine are oval.

Don

i will go to the shop and get you guys photos of the small o ports the big O ports and rect port gm heads

Originally Posted by pat mccarthy

i will go to the shop and get you guys photos of the small o ports the big O ports and rect port gm heads

Ok Pat, we're sitting here tapping our feet.

Don

Originally Posted by Itoldyouso

Ok Pat, we're sitting here tapping our feet.

Don

don tomorrow i am at home now the only running i going to do is going down the road for taco bell

I love it when a plan comes together.

1. Taco bell
2. Foot tapping till tomorrow.
3. Pat will solve the mystery once and for all.

Thanks Pat.


One question, who pays for the Taco Bell?

Thanks Pat. I owned a 427 trpower vette with closed chamber ovals. The runners I believe were a lot more round and smaller than the ZZ heads.

Be careful with the Taco bell. It can result in blown o'ring seals down yonder.

Kitz