I have stock 500 efi's in my boat and a guy I know told me at a poker run that the iron heads where holding me back. Is this true that on stock power I would be able to get a little more from the motors by making the switch?

its not so much iron vs alum in your case unless your upping the compression too.. what it comes down to is that you have a GM rectangle port head, with head technology straight out of the 1960s. You could bolt on a decent set of modern aftermarket iron heads and see a nice gain. There are head comparisons out there...do a little searching, from the stock rectangles to good aftermarket can be a significant difference.

I had a set flowed last month. As they were out of the box. They are being slightly ported/cleaned up as we speak. They were flowed on a 4.500 bore fixture.

I can't wait to see the before & after results of these!

The man asked for some numbers...you come back with "I got some numbers last month" but you dont post no numbers.. Your like Eddie Murphy and the ice cream truck...

"You got no ice cream you got no ice cream, you got no ice cream/ You on the welfare, you on the welfare/ And you daddy's an alcoholic/ Want some?/ Psych!"

Your lucky he dont send his Aunt Bunny to go all goony goo goo on your azz throwin shoes and sh!t......



. https://www.youtube.com/watch?v=0bXpQVJwlsY

I`m just gonna get it out of the way ... Mild your flow bench is happy and the correction factor is way off.
ok post away.

Gimme Fuel, here is the info you requested.

The 308 Darts, had some work done to them. Performance valve job, little chamber cleanup/polish, some bowl/throat work. They were my old heads. For the flow test on the EQ heads, we used my old valves, just for a comparison of the heads. The valves themselves, kind of suck. There was no back cut on the intake valve, and the exhaust valve, was a manley nail head valve. The EQ heads will have custom valve jobs, chamber porting/bowl work, 30 deg back cut on the intake valves, and new ferrea tulip exhaust valves. The EQ head was literally pulled out of the box, and went to the flow bench. All three of these heads were flowed on the same bench, same 4.500 bore fixture. No pipe on the exhaust.

It will be interesting to see how the EQ heads respond with some hand work. From all the head guys I've spoke with regarding this particular head, is that they respond very well to porting. Several guys now have CNC programs for them. They are very popular with the truck puller guys.

Those turned out very very close to the Dart 308 albeit a slightly larger runner. Looks like some great flow for the money. I had a set of Dart 308 on my first 540 MPI build. Those things made some serious torque. I'm very interested to see how they do with good valves and a bit of massaging. Those look to be a heck of a big improvement over GM rectangle ports for not a whole lot more than refurbishing a set.

actually, my 308's were what they originally were stamped, but after some work, they actually measured 319cc and 315cc on the intake ports, prior to testing them.

I'm sure with better valves, the flow numbers on both would be up a bit. At 425 per casting bare, you can't beat it with a stick. The castings are excellent quality as well.

I know of a recent build that used them. Very light cleanup, 2.30 valve installed. 540ci, whipple, low rpm deal. made 900hp with 8lbs boost, at 5500rpm. A little more cam and rpm, 1,000hp was on the table.

Great now my secret flow numbers are out there for everyone to see.. don`t you know you`re supposed to keep that stuff off the internet!? What if someone benefits from all your hard work or trial and error??
- end sarcam-


:rolleyes: