My roommate just picked up a set of oval port heads with the casting number "3993820" I did a search on these and there didn't really seem to be much to say so I thought I'd ask. The Mortec site lists these as "3993820....71......oval...OPEN...402, 113cc chamber, 255/114 ports" They seem pretty similar on paper to a 781 or 049 head other than the smaller combustion chamber size. Would these be decent for a 10:1 468 or 496 street motor? Would these support 575 to 600 horse? Would a cleanup and a set of 2.19/1.88 valves make as big a difference on these as a set of 781 or 049 heads? And lastly, any tricks special to these castings that anyone knows of? Thanks in advance for your help.

-John

OK, I guess I'm not very good at searching. I tried it again with some difference keywords and seem to have a lot of info to read over during lunch. I'll be sure to dive into these other posts, but if there are any other tidbits I should know, I'd appreciate it.

I have the 820 heads and have no problem with them,I have 2.19 & 1.88 valves installed.I hope to make it to the track soon,just need to get the driveshaft loop installed.I been busy with the house,have a baby on the way in july! Heads (http://users.erols.com/srweiss/tablehdc.htm#BBChevy)

I also have them with 2.19/1.88 valves and hardened exh seats. No problems here.

those heads are pretty good ones, IMO. my dad had a pair on his 427 and it screamed. Steve Schmidt built the engine and since those were the heads that were available, they were used. they were slightly ported by Schmidt and had 2.19/1.88 valves installed. a buddy of mine actually had the engine built and had it in his 67 camaro and it ran 7.50's in the 1/8mi with 3.73's, 3000 stall, street tires, mufflers, and 3600lbs. it just had a Torker II intake on it, probably would've ran a tenth or two quicker with an rpm intake.

I agree, used them a few times, I think it's one of the best heads for a street motor. In fact I have a set I'm working up right this very moment for a 454. I'll probably run a hyd roller cam with around 225°/235° duration and .580" - .610" lift. Good flow but good velocity at the same time, and you can use a piston with a small dome, and the chambers don't shroud the valves much at all. The bigger valves DEFINITELY help, especially on a larger motor, or if you do any port work. They kind of need port work usually, especially in the bowl area.

Originally posted by Yellow77:
The Mortec site lists these as "3993820....71......oval...OPEN...402, 113cc chamber, 255/114 ports" I wouldn't take the 113cc rating too seriously. I had a set of 820's built for my father's 417 (396/402 bored 0.080"). They cc's at 122cc's. I would have them cc'd before ordering pistons, at the very least.

Oh, and they are a great head. My father's '59 Chevy long bed/fleetside runs 13's in the quarter with no problems. Not bad for a no traction, heavyweight, truck.

Sounds like we scored some pretty decent heads. He paid only paid $390 for a complete, running 454 which I thought was a pretty good deal. Of course we had it torn down to the block within an hour but that's beside the point. Sounds like we'll talk to the guy who does the grinding and see what he thinks. Looks like we've got a lot of good suggestions to throw his way thanks to you guys. I really appreciate all the help. This guy did some 781's of mine. 2.19/1.88 valves and a cleanup job and they flowed 292 on the good intake. Any guess if these should flow similar numbers?

i'd say similarly equipped and equally ported they should be pretty close to the 781's, maybe a few cfm down, but it'll be close.