If running faster each season in your Pontiac is the credo by which you live, then there will come a time when your engine combination reaches a power level that causes a set of head gaskets to fail after just a few runs. At this point, about 650 horsepower, according to engine builder and HPP contributor Jim Taylor, it's time to O-ring the engine to keep the water and combustion contained.
Jim explained that the Pontiac engine is at somewhat of a disadvantage with regard to cylinder to head sealing in race engines due to the fact that it only has 10 head bolts per side, whereas a big-block Chevy, for example, has 16. Also, Pontiacs are thin cast so things can move around under high cylinder pressures. When the head gaskets do give up in a Pontiac, they tend to leak water more than actual cylinder pressure but neither is a good thing at 135-plus mph through the traps. In Taylor's experience, many engines producing 650-plus hp get only 5-20 passes before the head gaskets fail, unless O-rings are employed.
If this scenario is all too familiar for you, then it's time to O-ring your race engine. Jim related that it's easier for the Ford and Chevy guys because gaskets are manufactured with the O-rings already in them. However, no company that we could find makes such gaskets for Pontiacs. So, how do you O-ring your Pontiac engine? Should you groove the block or heads to accept the O-rings? Is this a process that you can complete on your own when you assemble the engine? These questions and more will be addressed in the following captions.
Who would have ever believed...
Who would have ever believed that a ring of thin steel wire fitted into the block was the fix for keeping the combustion process contained in the cylinders of 650-plus hp Pontiac engines? In extreme cases with very high cylinder pressures, receiver grooves are cut into the block and heads to contain the pressure, but according to Jim Taylor, most Pontiacs will encounter main saddle failure running pressures high enough to require this set up, so O-ringing just the block or heads will be fine.
O-ringing the block instead...
O-ringing the block instead of the heads is Jim Taylor's recommendation. He reasons that, "The heads will probably get more service than the block deck and may even be swapped for another set over the life of the engine." The O-ring groove is cut by the machine shop and measures .039 wide x .029 deep to accept .041 steel wire.
The ends of the wire must...
The ends of the wire must butt cleanly to seal each cylinder. Some builders prefer to cut the ends of the wire at a 45-degree angle creating a mitered edge so that the wire ends partially overlap when installed to seal each cylinder. Jim says, "That's great if you're Warren Johnson but filing the ends flat so that they fit tightly against each other is easier and will work just fine for this application." Here, Jim files the first wire end flat on a sharpening stone after it's cut.
To make the wire easier to...
To make the wire easier to install, it is wrapped around a piston to shape it. Jim begins with a piece of wire, which is approximately 14.130 inches for the 4.186 bore block that will receive it.
It's very important that the...
It's very important that the groove in the block is perfectly clean before the wire is inserted. Here a tiny screwdriver wrapped in cloth is used to clean it.
The installation process begins...
The installation process begins by inserting the wire end into the groove away from the water passages. A plastic-faced hammer taps the wire into place. Care is taken not to get overzealous and smash the wire.
With the wire installed all...
With the wire installed all the way around to the starting point, a reference is marked with a sharp chisel and then the wire will be removed from the groove to cut off the excess using that same sharp chisel (away from the open engine). The wire end will be filed flat on the stone so that both ends will butt cleanly in the groove.
Err to the long side regarding...
Err to the long side regarding your measurement before cutting the wire. If it's too long, as it is here, you can always cut again. If it's too short you will have to start the entire process over.
After marking and cutting...
After marking and cutting and filing once more, you can see the wire butts tightly and this cylinder is completed. The process will be repeated seven more times. Once done, the heads are installed sans gaskets and tightened to 25 ft-lbs in proper sequence to seat the wire. Then the heads are removed to check the O-rings. This is done to ensure that the wire didn't buckle once seated (wire too long) or that the butted ends didn't separate once seated (wire too short).
Jim has found that a plastic...
Jim has found that a plastic syringe does a great job of applying the Clark sealer that comes with the Clark copper head gaskets. This sealer will do wonders for keeping the water in its passages.
With O-rings in place along...
With O-rings in place along with copper gasket and sealer, Mark Erney mounts the head over the studs and onto the engine.
The nuts for the head studs...
The nuts for the head studs are then torqued in proper sequence in three pulls, 50-75-90 ft-lbs with molly lube.
Here is a previously installed...
Here is a previously installed head gasket, which exhibits the grooves that were pressed into it by the O-rings. The harder steel wire makes impressions in the softer copper and provides a better seal than the gasket could alone. As you saw, the O-ring process must start with the machine shop cutting in the grooves, but installation of the steel wire can be done at home during engine assembly if you like to screw 'em together yourself.