I bought these heads in a package deal. Can anyone help identify them.

 

. The other one has a 41 and the same 899 #

 

Looks like 993 to me.

Full casting # is 3998993.

TOTAL TRASH. One of the most common smogger turds from the 70s. Has been more recently resurrected as the choice on the low-budget phone company van replacement motor you can buy as the GM "Performance" "260 HP" model. Will make an honest 180 HP in the real world, just like it did in the 70s when THE EXACT SAME PARTS were all installed in vehicles as a new engine.

I hope you got at least something of value in the package...

 

Yeah edelbrock intake carb and valve covers and air cleaner and a distributor with an accel super coil so not hurt to bad for price I paid

 

buy a set of vortec heads or 113 vette heads promaxx alum and make some cheap power

 

The promax looks good!! How do you decide which one to use the 185, 195, or 210 cc

 

Intended CID & RPM

 

Is there a formula to figure it?

 

No... just kinda "rules of thumb" and common sense and such as that... for one thing not all heads with the same runner volume are the same, meaning there's NO WAY any ONE "formula" could account for them all.

 

So what would be the rules of thumb for a 350 that won't see anything over 6500 rpm with a 10/1 compression

 

For a mild street 350 run a 170-185 cc head. Larger than that will move your power band up higher and kill off some low rpm torque.

 

I'd mostly agree, as a starting point. Reasonable range to be in.

Your compression number is, as always, highly suspect; more likely than not, MUCH higher than what an ACTUAL build will come out to.

What's the MEASURED ACTUAL AS-BUILT deck clearance of the short block they're going onto?

Head material selection will strongly affect the target compression ratio. Aluminum heads REQUIRE higher compression than iron, by a half-point or more, due to the material's greater heat conductivity.