sutphen 30

learned that along time ago.

95NovaSpyder

iTrader: (2)

i was thinking about keeping the intake and using a spacer or notching out the plennum -

I was actually was thinking about the 800cfm quick fuel - i swapped to a edelbrock carb from the stock Qjet -had issues with Qjet - really helped the motor - not a fan of "stock" holleys, but i like the QF

I dont want to lose alot of low end so i was looking to keep cam near the 225-235ish duration with 112-114 lobe sepration - also looking at split lift/duration to help on the exhaust side of this - i have straight thru hull with no baffles

rexcramer1

As long as you are going in might as well copy the HP 450 rather than the 420.
HP500 roller cam, single plane, 800 Holley, Gil Exhaust
Has a nice little rasp to it

79formula

Yup. Sweet motors.

endeavour32

iTrader: (4)

Here is what I did to my 420's and while some will say it is over cam'ed, it runs great and idles just fine at 700 rpms.

Everything is stock other than the following-
Crane 741 cam
Split ratio Crane Gold rockers 1.8/ 1.7 ratio
Dart Single Plane intake- (don't use the knock off dart intake, from what I could see it looks like a dart but the runner size is different, bigger)
Holley 800 (HP 500 carb) jetted to HP 500 specs.
Morel Hyd roller lifters
Gill Exhaust with Dry to tip tails.
Wilson 2" 4 hole carb spacer

I did run a smaller cam in this combo as well as an RPM intake. The cam was a reed cam, it was supposed to be around 232/237 with .578 lift on both intake and exhaust. The cam was pretty lame and I really didn't care for the performance of it at all. As for the Dart vs the RPM, the Dart was better so it stayed on. If you are using the standard Gil tails don't go bigger than the 731 cam. Also change your stock springs to Isky Sp-8005. They are a great spring that won't kill your bank account.

If you are positive you are going to switch to AFR ovals down the road, buy the Dart oval port intake, it will work on you rectangle heads. It it one of the few oval port intakes that will work on the stock rec port heads. I've also ran the AFR 265 heads on a past engine and they are an excellent head for the 454.

Good luck with your project

bck

FWIW to the op, my old engines from Innovation Marine were very similar to what you are doing with the rect heads and GM high rise dual plane. Innovation put a 2 inch open spacer on top of the intake. These were never run on a dyno but Innovation seems to know what they're doing.

endeavor1

iTrader: (3)

We need a "Skank Off" to settle this dispute.


I wanna see some pix of skanks

E32.... Can a formula pull as hot of skanks as the Beak brotherhood


GAME ON

SB

iTrader: (1)

This is true, putting an open spacer on a dual plane can add good hp, however, just as an fyi, air/fuel distribution get's fubard even more. Reason why it makes more power is a dual plane intake only lets each cylinder see air from two throttle bores vs all four. The open spacers lets each cylinder draw fom all four. Also, since a dual plane cuts the plenum in half, the air 'reservoir' is quite small. Most carburetors placed on dual plane intakes are sized too small. If you take the same engine but switch intakes only, the dual plane could use a bigger carburetor than the single plane. It's just physics.

MILD THUNDER

iTrader: (3)

Yes, I am sure the 4cc chamber size increase on those cnc brodix BB2's, would have been detrimental to the build combination you have there. The added flow from those heads, better designed combustion chamber, and ports, would have totally made it a "dog". Good thing you kept the stock 1960s iron rectangles. Sounds like you have some really sharp guys advising you on your engine endeavors .

bck

These came with 830 cfm Holleys. They had the choke mechanism removed right from Holley but the tower was still there. List 9381