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882 or 193 Heads

31K views 15 replies 8 participants last post by  BogiesAnnex1 
#1 ·
I have a 350 sbc in a 1979 camaro with a close ratio 4 speed manual with 308 posi. The engine not quite sure on the cam size but it has 882 heads, performer intake, 1" carb spacer and i have either a holley 600 or carter AFB, long tube headers with true duals only 2.25" exhaust. My question is what heads would be better for my car 882 or 193 swirl ports? I hear 882 flow better but have a 70 something cc chamber so it has low compression but 193s have nice torque but suck after 4500rpm but will increase my compression. But i also heard that some of the engines that had 882s had high compression. Yes i know vortec heads are the best but i dont have $600 for a good set. Can anyone help me. Thanks
 
#4 ·
If those were my two choices for heads, in your instance, I would choose the 193 heads. When I've dynoed them on what is probably a similar engine, dished pistons, mild cam, four barrel, they dropped like a rock after 5,000. But they made 360 pounds of torque starting around 2500 and carried out pretty well flat. With your gears they aren't a terrible choice, just beware they have a different intake bolt pattern, slightly, where the center two bolts on each side are more upright than the others. Heads and or intake can be modified to use an old style intake.
As for the 882 heads coming on high compression engines, the highest I've seen came in around 8.75:1 in a 72 camaro, which came with factory forged TRW flat top two valve relief pistons.
Beware though, as both of those heads have a tendency to crack, so spend the few bucks to have them checked before spending the money to out them on.
 
#6 ·
You are going from a 76cc(nominal) head to a 64cc(nominal) head, so you'll see a big increase in power. If you do happen to have the flat tops, the compression will likely be too much for even mid grade pump gas. One thing we found with those 193 heads is they didn't like much timing or the motor would ping on the Dyno, but we were running it with cheap 87 octane pump gas.
 
#8 ·
1st of all,what are you gonna be doin with the car?Daily driver,drag race ???? I may be wrong,but,I don't believe a stock 882 will outflow a 193.Also,the 193 is a much more efficient head.With some cleanup & porting,the 193 makes a pretty good head.For me,the 193 would win hands down.Using flat tops with the 193 tho would prolly land you in the 10:1 CR.It's hard to give advise with the limited info you supplied,especially the cam specs.
 
#11 ·
The compression ratio and the cam timing must walk together. In and of itself increasing compression doesn't bring much to the party unless the compression is low against the point where the cam closes the intake valve. This is called dynamic compression or the Dynamic Compression Ratio (DCR); it is a computation of stroke used up to the point of intake closing. This dictates the entire performance of the engine from idle to the torque peak and is the reason why competition engines use massive amounts of Static Compression Ratio (SCR) to recover the bottom end power. The hotter the cam timing the later the intake closes in order to favor top end horsepower development. At lower RPMs in such an engine, the rising piston reverse pumps the mixture it took in on the down stroke back into the intake. This continues until the engine is drawing mixture at such a high velocity that the speed times the weight creates enough inertia in the mixture that it continues to flood into the cylinder against the rising cylinder pressure caused by the oncoming piston. This is why a long duration high lift cam move the torque and power peaks close together and much further up the RPM band than a mild cam.

But we're still left with the problem of the massive loss of torque thus power from off idle to about the torque peak. That's a lot of RPMs where the engine is really crippled so what to do to recover the lost torque and power (power being not much more than torque at an RPM times that RPM so big torque numbers at low RPMs make big power, just as lower torque numbers at high RPMs make big power. The solution, before I got side tracked, is more compression, this raises the thermodynamic efficiency of the engine by forcing the mixture density higher which gives a bigger bang when it burns. Obviously there are limits to how crazy you can get by many things but the big movers and shakers are the combustion chamber shape and the octane rating of the fuel you can afford to burn.

The other demand of a big duration high lift cam is gear ratio, as the torque and power move up the RPM band the engine also needs stiffer gearing to chase the power advantage and put it inside the operating zone of the vehicle. Part of this is because you can't ever get enough compression ratio to fully compensate for the cam timing and lift's impact to the off idle to torque peak zone. So you run up the gear ratio to give the engine more mechanical advantage on the bottom end. The other end of the problem of course is how much vehicle speed can you get for the RPMs the engine is capable of turning before it comes apart. So you’re stuck with this sandwich problem and where you're going to make compromises.

Now a close ratio 4 speed is going to want you to operate up on the power peaks. It is designed such that when you shift on the power peak it drops you back onto the torque peak so the engine doesn't have to work so hard as it would with a wide ratio gear box which will drop you under the torque peak unless you over rev it on the top end which might result in the engine going home in a basket. A close ratio gear box wants an engine with a whomper stomper camshaft. Plus with a 3.08 gear that wants an engine that makes lots of top end power for high speeds not necessarily fast acceleration. So for the street this is a completely messed up combination better served with a wide ratio gear box and a stiff rear axle, at least a stiff rear axle.

So to really be of useful help we need to know the cam you've got, specially the part number and brand or the intake closing point off the timing card should you have that. This the stroke and rod length along with piston to deck clearance, piston crown volume, head gasket thickness, and chamber volume will dictate the compression ratio selection which will dictate the head.

To open the obvious conversation it's impossible to beat the L31 Vortec and its many modern aftermarket relatives. It is well known that the L31 puts 20 to 50 horses on an engine with no other changes because it burns and breathes better, far better than anything that came before it. The 193 is truck head yes it makes good torque not so much from compression ratio as from the swirl vane in the valve pocket. But while that gives good low end torque it shuts the port off at 4500 RPM or less. Since power is again torque times RPM what you're lacking with this head is the ability to carry your set up of a close ratio 4 speed and 3.08 rear end to a place where the engine is making big power. In a drag race it will be like short shifting every gear. You won't get to a useful power band before you're forced to shift where it will drop you under the torque peak and the engine will struggle to get back up into its power band and will again get shut off about 1000 to 1500 RPMs under what it could rev to with a L31 style head. Not only that your intake won't fit the 193 any better than it will fit an L31, so a new intake is in the picture no matter what.

A compromise that has a chamber with most of the L31 features and will accept your intake are the L98 heads from the mid 1980s to early 1990's, there are several part numbers that have some different fitments available in iron and aluminum from GM. These at least the iron version were very popular with the marine versions of the 350. Casting 14096217 or 14101083 in iron make part numbers 10125377 for the 72 degree center bolt manifold from 1987 and up and part number 10159552 for the 90 degree center bolt manifold of 1955 through 1986 which is what you have. There is another similar casting 14011083 that also makes the 10159552 part number. Look carefully as these two casting numbers are almost the same. These are 64 cc chambers with 193 size ports that do not have the swirl vane in the valve pocket. Note you cannot grind out the swirl vane from and 191 or 193 heads.

The Z28 and Corvette L98 engines used an aluminum kissing cousin to the heads above this casting 1401128 that has a 58cc chamber and accepts the 90 degree center bolt intake such as you have. There is also casting 10088113 which makes the later version L98 using the 1987 up 72 degree angle for the center bolts. This head is found on the ZZ crate series engines as well.

If you get the wrong part number for the angle of center bolts that you have you can either Locktite a section of threaded rod into the center bolt's threads (steel in iron; aluminum in aluminum) and redrill /tap for the angle you need or egg the manifolds bolt holes. Or buy the correct intake. These L98 heads in iron and aluminum are pretty common on EBay and are almost but not quite the equivalent of the L31, they lack the beak extension between the valves from the squish/quench deck and porting isn't quite as good but the spark plug is moved to the center of the chamber like the L31, the chamber is the same volume and the valves are the same size. The aluminum version with the 58 cc chamber is used with a .053 thick head gasket which ends up making about the same compression as the cast iron version. But Wait! Aluminum moves heat faster than cast iron so you can push the compression up a ratio without getting into detonation vis-a-vis cast iron. You can take advantage of this by using GM head gaskets that are thinner than what the production engines came with. GM 10105117, this baby is a multi-layered stainless steel gasket with a 4.1 bore, it's .028 thick, works with iron or aluminum heads, good for holding back high compression and tolerates some surface irregularities in the deck and head surfaces. The other is GM 14096405, stainless faces over a graphite core, 4.1 bore and .028 thick. This thing hangs tough on uneven surfaces and puts up with high compression ratios. Good for iron or aluminum, this makes a good race engine gasket as it's very tolerant of engines running very hot. It lets the block and head move around to adjust for their temperature differences without breaking its seal.

So this is a lot to digest and I'll cap it for now.

Bogie
 
#13 ·
i just posted video of my 307 up. making center bolt holes line up is not hard at all. dremel and 20 min. just grind intake to make room for bolt.

tpi heads will be decent but will not make high rpm power very well on 350+ ci. i would get 416's or 081's get good compression so you can run a good cam. listen to the post above about dcr. If you match your compression and cam the motor will be very responsive and you will be happy with results.

those heads can be found on craigslist and junk yards all over.

p.s. i score vortecs on the regular for 200 set off old engines. just make sure they not cracked, alot are..
 
#14 ·
For a cam its pretty much stock, even with true duals you can kinda hear the cam but it does not really sound like it has a cam. With the close ratio 4speed and the cam and the 308 gears im shifting at about 4600rpm and it feels like i didnt even shift because it only goes back down to about 3800rpm and at about 80mph im at about 6000rpm. With the 308s if i tap the gas it can easily smoke the tires.
 
#16 ·
Why do you shift so low?

What do you mean at 80 mph its at 6000 RPM with a 3.08 axle is this 4th?

What size tire?

A stock 79 350 is a pretty doggy motor, this is the heart of the first generation of smog era engines and they really suffer from being under cammed and undercompressed, but the heads don't lean much toward pumping the compresson up with unleaded gas as fuel.

Bogie
 
#15 ·
close ratio gear box and over weight Camaro I doubt it is very scary when you stomp on it. Spend some time and take out 2-300 pounds of dead weight,,,( bumper and door braces)If you bother to swap heads,get something a lot better. consider a deeper first gear if you want to launch that beast..Put a 3 inch exhaust system on the car.I made the mistake of using 2 1/2 inch with turn downs,no x or H.car went 4/10s faster with mufflers removed
 
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