20 years of technological development: Chevy cylinder head content

here are a few pics i took yesterday of my newly acquired vortec heads from a 97 Yukon next to the original 882 castings that came on my 74 Monte Carlo.. some people don't know what makes a "Vortec" head a "Vortec", and think it's just the valve covers.. just a couple of quick shots of the chambers and ports and what not..

1997 vintage Vortec is on the left, 1974 vintage 882 on the right.

here is a vortec intake gasket held up against the intake side of the 882 head..

i actually sold the 882 heads for $10 to a friend that thinks he will be wise to throw a ton of money at them and make a lot of power in his mud truck.. i tried telling him to just get some Vortecs, but he thinks the 882's are the best heads ever invented for a 350 Chev..

maybe just for kicks i'll grab one of my 305HO heads and visually compare it to the vortec, and if i get really ambitious i'll pull one of the heads off the 94 Caprice LT1 that's sitting in my Camaro and show how they are similar to the vortecs, but not quite the same.. i just wish i had a TBI 350 head just to show how the early centerbolt heads differ from the vortecs..

vortec chambers produce very efficient combustion, and you'll see about a full point of static compression increase due to the smaller chamber volume. i went with the thinnest head gasket available when i put the vortec heads on the 327 in my V8Vair (flat-tops with valve reliefs), and the car ran 13.78 @ 104 at the challenge, with a 2.005 60-foot. you will love the vortec heads, but you will need an appropriate ignition curve in your distributor.

The 882 was generally regarded as the worst 1.94 head GM ever made. You couldn't give them away here, but when I was racing limited small block motors, a set of 441's was worth a small fortune. The reality was that there is little to no difference, aside from a few cc's of combustion chamber. If only we were allowed to run the Vortec heads.

AngryCorvair wrote: vortec chambers produce very efficient combustion, and you'll see about a full point of static compression increase due to the smaller chamber volume. i went with the thinnest head gasket available when i put the vortec heads on the 327 in my V8Vair (flat-tops with valve reliefs), and the car ran 13.78 @ 104 at the challenge, with a 2.005 60-foot. you will love the vortec heads, but you will need an appropriate ignition curve in your distributor.

i know all about the vortec heads- i had a set on the HOT cammed 355 that was in my 71 Nova.. it was a beast- 87 octane with 10:1 compression and what a couple of magazines claimed to be around 400hp in an engine that idled smooth at 750 rpm with 17" of vacuum and would average 17mpg with 3.70 gears and no overdrive..

but this set is going on an L69 305 out of an 86 Caprice that i'm putting in my 86 Camaro. shooting for 30mpg's with this thing..

In reply to novaderrik:

Sounds like a nice project. Intake & exhaust planned for project? Trans? Just curious.

just a vortec Performer intake with a quadrajet. i wish there was a quadrajet compatible intake for these heads that had a hot water crossover to get the intake nice an hot to up the thermal efficiency, but if nothing else i work at a machine shop and i'll make a spacer with a water crossover in it that goes under the carb similar to the one that Smokey Yunick designed in the 70's and Moroso sold for a while. ramming cold air into the carb and heating it up in the intake is a good way to squeeze out some stellar mileage numbers..

not sure on the exhaust side of things yet- i'll use the vortec exhaust manifolds that the guy threw in with the heads if they'll clear the chassis, if not Hedman makes normal long tube hedders that have good ground clearance.. the exhaust after that will be an X pipe and Dynomax Super Turbos with the inlet and outlet on the same side of the case mounted under the rear seats with a turnout on each side that exits in front of the rear wheels pointing 45 degrees back.. maybe with some sort of an oval shaped NASCAR style outlet just to make it look extra zoomy and some vacuum operated cutouts made from some heat riser valves to bypass the mufflers just to up my redneck Camaro style points. i really, really hate the way they try to force you to run the exhaust on these cars, so i'm gonna weld in some 2X2 subframe connectors behind each rocker panel and hang a normal double hump trans crossmember from that and take all the factory bracing that holds up the stock trans mount to open it up for the exhaust.. trans is a 700r4 i've got laying around and the rear has 3.42 gears.

this should get me close to 30mpg, and if not i'll find another rear end and some 2.56 gears to put in it..

About the outlets, thought about some Boom Tubes from Dr. Gas? Seems like about what you're looking for.

Interesting about heating the intake for better economy, always thought keeping it cooler was better.

pres589 wrote: About the outlets, thought about some Boom Tubes from Dr. Gas? Seems like about what you're looking for. Interesting about heating the intake for better economy, always thought keeping it cooler was better.

no boom tubes- they don't fit into my plan of keeping it quiet when i'm not WFO.. and they are 'spensive.. but yeah, that's kinda the look i'm after- not that looks are important on a beat up POS 3rd gen Camaro with "BECAUSE RACE CAR" stenciled on the hood, but they will visually hide the mufflers.. and i can make them pretty easily..

regarding the heated intake manifold- it works.. i've played with it myself. it was the difference between 26mpg and 30mpg in a 76 Monte Carlo i had in the early 90's that had no business getting that kind of mileage. it had a home made dual snorkel ram air air cleaner with dryer ducting going to the front of the car kept the carb cool enough that it had beads of water running off it when it was 100 degrees out and the open exhaust crossover in the intake manifold made the intake too hot to touch..

I was thinking about a similar setup for my 91 C1500, just get one of those TCI adapters to use the stock TBI, and either long tube headers or the vortec exhaust manifolds out to a true dual setup. I think Dynomax or Magnaflow makes a muffler with a built in x-pipe. Should have good power and decent economy, better than 12 mpg in daily driving anyway.

06HHR wrote: I was thinking about a similar setup for my 91 C1500, just get one of those TCI adapters to use the stock TBI, and either long tube headers or the vortec exhaust manifolds out to a true dual setup. I think Dynomax or Magnaflow makes a muffler with a built in x-pipe. Should have good power and decent economy, better than 12 mpg in daily driving anyway.

try to find one of these used.. they used to be a $200 part from GM..

http://www.summitracing.com/parts/NAL-12496821/?rtype=10

Couldn't just about any Vortec intake manifold be used with the proper carb pad to TBI adapter?

novaderrik wrote: but this set is going on an L69 305 out of an 86 Caprice that i'm putting in my 86 Camaro. shooting for 30mpg's with this thing..

Sweet Jeebus, please keep us updated on this! I'm considering a 305 Caprice for a daily on my highway commute, and would love to see 25+mpg out of it. Now if I could also conjure a way to jam a five speed in it easily...

ValuePack wrote:

novaderrik wrote: but this set is going on an L69 305 out of an 86 Caprice that i'm putting in my 86 Camaro. shooting for 30mpg's with this thing..

Sweet Jeebus, please keep us updated on this! I'm considering a 305 Caprice for a daily on my highway commute, and would love to see 25+mpg out of it. Now if I could also conjure a way to jam a five speed in it easily...

the Caprice that it came out of would average 28mpg in mixed driving.. it was a nice low mileage stone stock 305/700r4/2.56 geared 86 Caprice Brougham that only had cruise control, functional AC, and the cushy cloth seats.. it was like driving your couch down the interstate at 80mph. i think maybe the sagged stock springs helped the aero out a bit- it was at least 2" lower than stock..

a couple of guys on another board think that 30mpg will be easy in the Camaro since it's probably 800 pounds lighter and more aerodynamic and the vortecs are so much more efficient than the stock L69 heads. hopefully i'll find out in the spring.

How do you put these heads on an older block? My 350 has perimeter valve cover bolts.

Thanks,

Rob R.

In reply to wvumtnbkr:

You buy new valve covers.

wvumtnbkr wrote: How do you put these heads on an older block? My 350 has perimeter valve cover bolts. Thanks, Rob R.

vortec heads are a straight bolt-on to earlier blocks, but they require a vortec-specific intake manifold due to intake port shape, cooling passage location, and of course the number / location / orientation of intake-to-head bolts.

In reply to pres589:

Well yeah, but what else?

In reply to AngryCorvair:

Thanks!

So I can just get a stock intake manifold from a vortec powered vehicle and be golden? (I guess I should get those valve covers too).

How can I tell which heads are Vortec?

wvumtnbkr wrote: In reply to AngryCorvair: Thanks! So I can just get a stock intake manifold from a vortec powered vehicle and be golden? (I guess I should get those valve covers too). How can I tell which heads are Vortec?

IDK about the stock intakes because I rocked a carburetor. There are only two casting numbers for the 5.7L vortec heads afaik, 10239906 (#906) or 12558062 (#062).

here's where the casting numbers hide:

and here's the casting mark you're looking for on the end of the head:

Do I need to change my rocker arms, pushrods, etc... for this swap?

For the uninitiated among us (myself included), can someone outline the significant differences between the 2 heads and explain why one is better?

The factory intake that I know of is the central port injection (CPI) job from trucks. It's a long story but that one has "avoid" written all over it. Like a diesel that uses a distributor pump but with gasoline and with reliability problems as they age.

Unless you can machine and weld an aluminum intake the best route is to get a vortec-specific intake manifold. At that point you could go with a carb, a TBI in place of a carb, or some kind of port fuel injection and throttle body.

Others here are smarter about this stuff than me but this should give you some idea of what is available from the factory; nothing you want to deal with. GM Perf Parts has an intake but there are a lot of other options. I think that the Vortec head has enough good qualities to make it worth dealing with if you also like carbs or the carb-like TBI options.

scardeal wrote: For the uninitiated among us (myself included), can someone outline the significant differences between the 2 heads and explain why one is better?

the heads bolt right onto any small block with stock head gaskets and bolts.

you need the 87 and newer self aligning rocker arms and matching center bolt valve covers or expensive and leak prone adapters to run the old perimeter bolt valve covers.

you need a vortec specific intake manifold and vortec intake gaskets- don't think you can just drill the old pattern into the vortec heads and use any old intake manifold because the intake ports are over 1/4" taller.. see my pic in the first post with the intake gasket held up to the old head. if you happen to have a Bow tie raised runner intake laying around you could use that with the intake bolt pattern in the head redrilled, but those are only available in single plane configurations and only for high rpm stuff.

and that's it.

as to why the vortecs are better- just look at the pic of the chambers and the intake ports.. the chamber introduces a lot of swirl and has a good quench surface. the intake ports are taller and have a smoother shape to them, which helps the air get around the intake valve. the exhaust ports are straighter and smoother than any other small block head.

the set i had on my 71 Nova allowed me to run cheap 87 octane swill from any pump in an engine with 10:1 static compression ratio and run only 34 degrees of total ignition advance compared to the 36-38 or so that most other small blocks require. i was running a true flat top piston with thin head gaskets for .040" of quench, which is why i got away with a combination that should have rattled itself to death on 93 octane..