Dart intake? Brodix or Dart Heads?
I'm building a 496 and have these heads-6272292, oval port, 2.06/1.72, I'm trying to keep it mid to low budget- can I get new valves and have the heads milled larger? I have a friend in a machine shop that will do it cheap. What size valves do I want for a moderate cam-say like 250 to 270? Is that considered moderate? Should I go larger? It is still a 496.... but will be almost entirely street. I got this car for 100 bucks and block and heads for 300 so now the expensive stuff comes, I know.
Does anyone know about these Dart heads for my 496? I want to run pump gas, and drive in the street 99% of the time. But I want gobs of mid to high end torque to like 6500RPM. I don't think low end will be a problem with a 496.
Chevrolet: 396-454, 119cc combustion chamber, 345cc intake runner, 2.30 in./1.88 in. diameter intake/exhaust valves, 1.625 in. diameter double valve springs, angled spark plugs, assembled, 23 degree, aluminum, Pro 1 head
Or these Brodix, they seem like a good deal;
This Dart intake is actually made for my tall deck and I can get one used cheap; it has rectangular ports and is named BBC.
but this is good and cheap, I just need the spacers; Edelbrocks;
Chevrolet: 396-502, oval port, idle to 5,200 rpm, Street Dominator intake manifold
This intake manifold fits carb flanges 4150/4160. It features low to mid-range powerband, horsepower peaks at 5,200 rpm, oval port heads, and no EGR provision.
This Performer intake manifold for Big Block Chevy is a dual-plane, low-rise intake with a 180 degree firing order and patented runner design that you won't find in competitor brands. This design provides torque over a wide rpm range, especially off-idle through mid-range. It also provides improved throttle response over a stock manifold. It's 50 state legal when installed on 396, 402, 427, and 454 with an OEM carburetor.; 1965-72(1973 non CA) passenger cars and 1966-83 trucks; except stock equipped EGR.
Any suggestions would be greatly appreciated, and the cam would be matched to these parts of course.
Last edited by Slowass72 on 01-20-200
First the Oval port head does not have enough runner volume to support 496 CID at 6500 rpm. To do so you are going to need a square port in the 320 CC range. With the heads you have and that CID your looking at about 5200. I would suggest going with an air gap intake.
Larger valves will help but then due to the runner volume you are limited. I would put a set of 2.19 and 1.88 in the head. This will help move air in the mid lift numbers.
I think the 240cc runner if the dart heads you are looking at would be too big. I am getting ready to build a pump gas 572 and AFR only recommended a 335cc runner head for that motor being taken to 6500-7000 RPM. My dad and I are also in the process of building a pump gas 496 being rapped to 6500 RPM. I spoke with comp cams and some motor builders around here, and they said that I was on the fence as far as if I should go with ovals or rectangular. Pretty much the ovals will have more torque and the rectangulars will have more hp. We decided to go with a set of 781 ovals that we had polished and ported and fitted with 2.19 1.88 valves. We got a custom grind comp cams mech roller with duration in the 265@.050 range and .650 lift. They said that that motor with that cam should make power to 6500 RPM. Another thing you might want to think about. If you decide to go with a set of Rectangular heads, I would look at the AFR 315cc head. They are $3000 for an assembeled, 100 % CNC ported set, but I talked to AFR, and they said that they built a 496 with that head that made 750 hp at 6500 RPM on 10:1 compression and pump gas. The AFRs are $1000 more than the heads you are looking at, but for a CNC ported dart BBC head, It costs $4000, so in that light it isnt so bad.
That info will help me a lot, I think I will just have my valves enlarged to 2.19/1.88 and port them some more. The dart intake I saw looks like the best one (especially for $100) for my budget. It does have rectangular ports but I'm told by several people here that doesn't matter.
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