vette406

im trying to pick out new heads for my 406 buildup and i went to a machine shop to see how much they charge to drill in steam holes and the guy told me that they werent necessary and that it would run cooler without them. i always thought that you had to have them. does anyone know if they are neccesary or if there just there thanks :crazy:

ORVette

I've always heard you need them for anything but full race applications (primarily above 3500 RPM's). Anyway, they're easy enough to drill yourself. Cast iron drills easy, just mark them from your head gaskets and center punch them. Take your time, and make sure to thoroughly clean out any metal shavings before re-installing. I've never done it, I'm just repeating what I've heard, but I think it's accurate. Surely some of our 400SB guys will post further info.

1979toy

I'm building up a 406 myself and ask the same question a few months ago here and on a drag racing board. The replys were split even on both boards. I went ahead and drilled mine myself using the gasket as a template. I figure Chevy didn't put the holes in just to look cool. (pun intended)

MotorHead

I guess there are different opinions, the guy who is going to build mine is going to drill the heads :D

CHRIS718

we build many 400 sbc motors at ckperformance.com and never do we not drill steam holes in the heads on street engines ,or street strip engines.here is the data straight from the gm textbooks:DUE TO THE 400 CID SIAMESED CYLINDER WALLS 6 STEAM HOLES ARE DRILLED IN THE DECK SURFACE BETWEEN EACH CYLINDER TO AID WATER CIRCULATION AT LO ENGINE SPEEDS AND TO VENT STEAM POCKETS AND AIR POCKETS.IN PRODUCTION 400 CID ENGINES THESE HOLES CORRESPOND TO MATCHING HOLES IN THE HEAD GASKET AND CYLINDER HEAD.ENGINES WHICH WILL BE USED IN LO SPEED APPLICATIONS SHOULD HAVE THESE HOLES DRILLED IN AFTERMARKET OR NON 400 CID GM SMALL BLOCK HEADS W/OUT THEM.IF THE ENGINE WILL OPERATE PRIMARILY AT SPEEDS ABOVE 3500 RPMS THE HOLES ARE NOT NECCESSARY,AS THE INCREASED WATER CIRCULATION WILL PURGE THE COOLANT SYSTEM OF STEAM AND AIR.this means all the street 400s need them .just built a street 406 for my el camino.its is a plus 40 400 /10.2 compression /dart 215 iron heads w/2.05 1.6 valves /crower hydraulic roller .488 .550 260 270 110 lca/performer rpm w/750 carter afb/ 1 and 5/8 hooker super comps/700r4 with 89 ho iroc valve body and 98 s/10 2050 stall lock up convertor/grand national 8.5 rear with 3.42 ratio.what do youy think ?380 horsepower and 400 ft lbs torque possibly?this is by no means a race race motor just something fo reliable long trip usage w/out eating my wallet .anyone running a similar combo?on long trips itll get the 600 afb .

Jack71

I'm having mine drilled. My street motor will spend 99% of its time below 3500rpm. What's the harm in drilling them??? The last thing I want is a motor that overheats at a stoplight.

There is a process for drilling the holes at the proper angles too.

CHRIS718

thats correct .if you drill them straight you wont hit the water jackets.

vette406

ya i think im gonna have them drilled then. by the way what do yall think of aluminum fastburn heads w/ i think 200 intake runners and 2.02 -- 1.60 valves. this will be a daily driven car. how do they compare to other heads with a similar setup

Armstrong

Here is the link to an interesting article in Chevy High Performance Mag about a build up of a 406 with Vortech heads.
Looks like a killer setup

http://www.chevyhiperformance.com/te.../148_0306_406/

The Money Pit

When I was looking for heads every article I saw that either flow tested or dyno compared heads showed AFR on top of the heap.When I priced them they were only $250 bucks more than the others.
(By the way,AFR drilled the heads for me.)
I often do things then later wonder if I'd done this or that instead would it have been better,and I hate that.So I figured if I baught the other heads for a few hundred less,then a year later ported them,I'd end up spending the same or more money,on top of tearing down the engine twice,etc.
So far I've been happy with the AFR 195's,and for a street engine I don't expect I'll be trying to build more power than I already have.

Now if I can just plant all that power to the pavement! :auto:

427V8

I would seriously look at the Vortec heads. They are cheaper and quite good performers too.

BTW I have the AFR's, Vortecs wern't mentioned much when I built mine...

vette406

cool i think ill use them. what do yall think of using aluminum heads on a daily driven car. will they warp real bad. i usually dont have a problem with overheating. any info would be appreciated
thanks :chevy

Schmucker

Now what if I have an electric water pump circulating the fluid at a constant speed. Let's say it is as if the engine was at 3500rpm. I wouldn't need steam holes then, would I?

427V8

Aluminum heads are fine for a daily.

electric water pumps are for drag racers :rolleyes:

Drill the holes man!

joe73vette

it takes only half an hour to drill all the holes yourself. expecially in aluminum. just do it! joe

The Dude

Have the machinist drill the holes.
Don't do it yourself because half of them must go in at an angle. You might fug it up without a drill press and a solid stand that will hold the heads at the proper angle, It doesn't cost much--$10-$20.

boredsoIstrokedit

IMO, Vortec and a 400 are not the best choice. You might as well go with a 350 if you are going to spend the money on vortec, and not couple hundred more for a MUCH better head. :cheers: