The "402" in my chevelle i just found the head numbers and came up with "L29 70"
From what ive come to understand is those are 1996+ bbc vortec heads with small combustion chambers and restrictive intake ports.
Is it worth trying to put any money into it, or should I just try to build up a new motor the way I want.
it runs and drives well enough, burns a little oil though it may just be an intake leak.

Are you sure they are vortecs? What is the casting number? I don`t know everything about bbc`s but I`m pretty sure the vortecs are a MK 5 or MK 6 head and they have a different water passage so I don`t think they will work on a MK 4 block. Find the casting number and that will tell you. It`s going to be longer than 5 numbers and there sould`nt be any letters in it.

If they are vortecs, then they are a decent torque head. The combustion chamber is too small for bigger valves but they do flow pretty good and with some bolw work they would be pretty good on a 402 with a mild cam.

Only other number on other than gm4t and "pass" is 8998820

Ummm, actually, i'd put my money on saying your heads are 3993820. Thats what was on the 402 that used to be in my car. I don't recall much about them just that they are from 71 and have 113cc chamber.

It very well could be 3/8's look a lot alike to me anyway.
Mortec says
3993820....71......oval...OPEN...402, 113cc chamber, 255/114 ports
3993820....71-84...oval...OPEN...454 Passenger and Trucks, 113cc chamber, 255/114 ports

That's an old head L is the month december 29 is the day and 70 is 1970 the year. 820 is the number your looking at.
With out a book but pretty sure it's an open large oval a good head.
If it's the original engine and you run your car hard and want it to preform build a 454 save the orginal engine. To many times have I seen guys blow up original numbers matching engines. It's a sad thing but numbers matching is what makes your car worth allot more than non numbers matching.
Good luck

those are standard 402 heads and I`ve seen them on 454`s too. They definately aren`t vortecs but they are still great heads. With bigger valves and some bowl work and a gasket match and they would be great performers.

You guys just made my day :D, I was getting nervous that I didnt get what i paid for.

An -820 isn't a squared off chamber smog head like an -818 is it??

Doesn't matter if it is b/c I figure both are fine worked over after you get your CR. up where it needs to be to run a decent cam AND todays crappy gasoline.

pdq67

Yes the 820 got a bigger chanber by removing the quench area. They work good on low compression engines. As far as large ovals, Chevy went from the 215, 206 sytle small bathtub chambers (96 cc) to the 101.9CC 290's semi open chambers to the 820 style then to the 049/781 open chamber style. 820's work on a 402 but keep the CR down to about 8.5/1.

So if I someday wanted to build a new higher CR motor i would have to abandon these heads?