[johnta1]

Back when, the round ports were worth a ton of money.
(no aluminum heads then)

Most didn't want to hurt them if they could use a run of the mill D-port with a power adder to go faster.
And the ones who did use round ports were faster than the D-ports.

After the aluminum heads were around the round ports were cheaper, but it was easier to port the aluminum heads and make more power than the cast iron heads.

Bigger volume, better porting will usually always make more HP.

[Dragncar]

Originally Posted by johnta1

Back when, the round ports were worth a ton of money.
(no aluminum heads then)

Most didn't want to hurt them if they could use a run of the mill D-port with a power adder to go faster.
And the ones who did use round ports were faster than the D-ports.

After the aluminum heads were around the round ports were cheaper, but it was easier to port the aluminum heads and make more power than the cast iron heads.

Bigger volume, better porting will usually always make more HP.

How do you know they were faster ? I have not heard of any 1600 HP twin turbo RAIV/HO builds. Now 2 D port versions gone that high.

[Scott Roberts]

Originally Posted by johnta1

Back when, the round ports were worth a ton of money.
(no aluminum heads then)

Most didn't want to hurt them if they could use a run of the mill D-port with a power adder to go faster.
And the ones who did use round ports were faster than the D-ports.

After the aluminum heads were around the round ports were cheaper, but it was easier to port the aluminum heads and make more power than the cast iron heads.

Bigger volume, better porting will usually always make more HP.

The round ports were left for restoration.. I had a set many years ago and didn't cut them up.. Like you said, I ran a ported set of d ports with the bottle... I'm glad many took the same route as me.. Too rare to cut up in my opinion...