They gained a bunch of power and flow. It's now proven that porting these heads properly can produce some serious power. They gained 17 lb ft. of peak torque but throughout the range they gained an average of over 20 lb ft. Horsepower is a different story, they gained 38 horsepower at 6000 rpm with a peak of 464hp at 5700 up from 435.

That's a big *** change in #'s. Since I am going to take my haeds off my 305 and prep them for my new 355 with new springs and stuff, I think I'll port and polish them. Although they did a bit of work to the intake side, I'll leave it alone as they only gained 9-10 inches of flow at .400 and .500 lift. There is much bigger margin for error on the exhaust side.

Ironically on a 425 horse motor which was my goal to begin with, porting the heads will bring me up to over 450 horse. Sounds good doesn't it? I also decided that after I break the motor in I'm going to get a centrifugal blower for it with an igloo over the carb. I want it to be a little more stealth than the pro-street look, but I want a supercharger really bad.

Here's the articles ( there are 3 ):http://carcraft.com/searchresults/?s...s=Vortec+heads

Here's the power comparison chart: http://www.carcraft.com/techarticles...rt/index2.html

 

I had similar results after porting LT1 iron heads for my "beater", but mine were even better. The again, the larger valves, cam, springs, lightweight valve train, and overall balancing didn't probably hurt either. I was starting with a paltry 260-ish HP and 330 ft/lb. in the beaSSt.

 

That guy did a lot of porting to the intake side and really didn't gain much there, but the exhaust gained a lot, which is good because it was the weak point to start with, I think if I did a set I would do the exhaust like he did but I wouldn't mess with the intake except to gasket match it and a little bowl deburr, I don't think I would hog out the intake port like he did for such little gain.

 

Just PLEASE take the magazine HP numbers with a grain of salt. This board and others are littered with stories of people who built the same combo as in some magazine article to get whatever- 400, 450, 500 HP or more, dropped the motor into their car and ran a mid 13s with it. And yes, several of them know how to tune and setup a car reasonably well.

A LEGIT 450HP street drivable 350 is NOT easy to do for the weekend wrench. You have to contend with mufflers in the exhaust, limited hood clearance and other "real world" stuff that the magazines rarely deal with in their buildups.

 

These numbers are consistant with what we've observed with these heads on our bench too.

 

Check my sig. That was the first time out and I haven't even began tuning it yet.

 

Don makes my point for me. It takes some tuning time to get things really sorted out in the real world. Look where he's starting from with ET and MPH. Obviously, he'll get quicker and faster with tuning and experience but it's difficult to just slap a combo together and rip off mind-blowing times.