crutch for to large of an intake port?

[bc]

I have a set of heads that the mininum cross section measure 3.2". They are going on a 466 that will see 7000rpm. According to my math the heads only need a cross section of 3". Will this be a big problem? The engine needs to make decent power starting around 4000rpm. Is there something that can be done when selecting the cam that can help out with a head that is to big for the combo?

[SupStk]

That might be a good question for your cam guy. I personally would cam it based on the intended RPM range and compression ratio.

One of my customers had a converter that was down on stall for the application we built the engine for so it ended up with a nasty flat spot at the hit of the throttle. By installing a plenum divider and a little carb tuning we was able to make it workable. Might work in your case.

[dbusch]

you are about 700 rpm low to reach optimum velocity with 3.2" and 466 cubes. In other words, you need a trap and shift rpm of 7700 to make the head work at its best. You can bring the area down a bit if you make the cross section at your gasket on the manifold 3". If you need power down at 4000 you are going to compromise the entire engine. I suggest you go to a higher stall, like 5000. That way you can make the manifold size a little larger and make a bunch more power at 7000 rpm.

[crazycuda]

HAve you thought about filling the floor of the port with epoxy?

[67RS502]

You should stay on the small size (2" dia. and long length) with headers,
which would move your power band down some. Also put more compression in it.
You could also try a good oval port intake on it, that will help the midrange.

[bc]

Thanks guys. I have thought about filling the floor and I still might just trying to figure out just how much this will hurt me. I have thought about the smaller intake and exhaust and will be doing that. But I was wondering if a little less intake duration and maybe a wider lobe serperation would help with the over sized intake port.

[dbusch]

normally less intake duration coupled with more lift will do better when cross sections are a little on the big side, as well as a little wider lobe sep, like 113 or 114. Like i said, you could make the manifold entry 3 sq" and then taper it up to the plenum. You could just keep the floor a little high in the manifold and then fill in the step in the head with epoxy. With that cross section i would like to see the port flowing about 375 cfm. Tapering the manifold up to 3.5 sq" in the plenum will put you at 5000 rpm for peak tq on your 466. Do you now see why you need a 5000 stall? Your peak hp should come in at about 6500-6800 so you can shift and trap at about 7000-7200 rpm. This engine should make 775 hp without much trouble if you have 13.5 or 14.0 compression...

[bc]

Thanks alot that answers my questions.