Ok Guys, I know its like beating a dead horse. I have posted a few topics regarding Big Block heads and what I can get the most performance out of for my 396 bored .30 over. Ok, In the right Corner a set of 3856206 oval port heads that have been worked a little. The valves have been enlarged to 2.19 intake and 1.88 exhaust. And in the left corner a set of 3919840 rectangular ports heads, I do believe that have the same intake and exhaust valves if I'm not mistaken. I'm running a XE274 cam, Double roller chain, Speed Demon 750 Carb, Aluminum intake, All MSD set up. What head will give me the most power for my Big Block?????? :confused:

How high do you want to spin it? For anything short of insanity, the oval ports will be better heads due to velocity. That's particularly true with smaller displacement engines like your 396.

I ran a pair of worked over "206" heads on my 468 and it went 12.1 @ 118MPH. Considering the XE274 cam, I would go with the worked over "206" heads. They will perform better on the street, and most likely with that cam selection they will perform better overall. Now if you had said you were going with a 294 solid flat tappet in the 396 the 840s might be your cup of tea ;)

Ovals no doubt. I went 123.6 mph with ported Edelbrock ovals and a pump gas 454

Loving the input guys, Keep it coming, any technical info would be nice too smile.gif

oval ports for sure. at that cubic inch, even factory oval ports are a large head for a 396/402. no way i'd even consider running rec ports unless you had tons of compression and a huge roller cam, 4.56-4.88 gears, 5000 stall, single plane intake , and a light car. even if what you have was a 454 i would still say oval ports as long as you have lower compression and the same cam.

For sure, in the 396, my **guess** is that the rect ports won't outperform the ovals until it's well past 5500 rpm+ , or pretty much out of your useable range. The ovals will shine from 2000-5500, your main operating range. Not much of a debate really.

Build a high rpm motor or a big big rat to use those rects effectively.

I really appreciate your guys input, Thanks. Looks like I'm going to go with the Ovals :D

I just picked up a set of 206s just like yours. 2.19s and 1.88s I may actually bolt them on the old 461 and take the stock 215s off.

Let me know if you notice any difference Mike smile.gif

Have the chambers been opened up to unscroud the valves in your heads? I was always told by people that should know you couldn't do it on the very early heads. Mine have been opened up and hard seats installed for the intake and 1.88 ex (another thing that wasn't supposed to work) The heads came off a motor that ran until it lost a cam and show no signs of any water leakage. Maybe they are a good set of castings or the guy was lucky, who knows. Or maybe it's another of those old wives tales that you can't do it.

Well the 206's that I have are very nice, I'm going to take them to a machine shop and have them double checked before I put these on. I also may have them Gasket Matched along with my intake manifold.