Ain't she a beaut-the Isky...
Ain't she a beaut-the Isky Groove-O-Matic. This tool lets you cut your own O-ring grooves at home like a real machinist. The Isky kit has everything you need to go into business and it works great.
It was a simple plan. We built up a nice 500-plus horsepower street 440, a solid and basic combination packing a serious punch ("440 Resto to Rad," Mar., Apr. '01, Mopar Muscle). Were we satisfied? Well, yes, but we wondered what sort of numbers it could make with a little chemical assistance. Back on the dyno for a nitrous test in various stages, we got away just fine with a 150hp shot, making more than 650 hp and a staggering 760 lb-ft of torque. So, throwing caution to the wind, we rejetted the system up to 250 hp and made one more pull. At that point, our 440 literally blew its top. Those regular rebuilder's head gaskets we had used didn't stand a chance with the huge nitrous load and relatively low rpm. The cylinder pressures were just way too high. Actually, we got lucky, walking away with the 440 still in one piece; shooting for 750-plus horsepower out of a stock rebuild-style 440 may have been pushing our luck. This thing still had the original 30-year-old main bolts holding the crank in and nothing but some freshened old, standard 440 LY rods. Later, we realized we had also trashed a couple of pistons on that final pull, crushing their ring lands and making them into ashtrays.
Nonetheless, the rest of the combo had hung in there, but the head gasket problem made running big shots of nitrous impossible. We decided to go for the throat on cylinder sealing and toss out the composition gaskets in favor of a pair of Milodon's Dead Soft Copper gaskets, together with new O-rings in the block deck. We've used the gaskets on other high-compression 440s-even without O-rings-and never experienced head gasket problems with them. However, even with five bolts encircling each cylinder on the B/RB engines, head gasket problems do crop up with nitrous, blowers, or even serious compression ratios. For more moderate cylinder pressures, Fel-Pro makes a wire ring-reinforced head gasket that drops in place as a regular gasket-but with the bottle still waiting to be emptied, we determined that copper gaskets and O-ring wire made the most sense.
An all-night thrash session...
An all-night thrash session getting ready, some cheapo head gaskets, and this big bottle of N20 set to kill was a fatal formula for fireworks. At 700-plus horsepower at six grand, water began blowing out from under the heads, and we were done for the night. Problems such as this will make you pucker. Um, J.B., sorry about the dyno time.
O-ringing is a process that entails cutting a properly sized groove into the deck surface of either the head or the block, then inserting a wire ring all the way around the cylinder. This ring then sticks up above the deck surface of the grooved piece; when the head is bolted on with soft copper gaskets, the wire embeds into the gasket surface, adding a tremendous amount of unit loading to this critical area around the bore.
Making the groove for O-rings requires machining a deck surface; the simplest form for the groove is a true circle, which is also easiest to cut. Some specialized race machine shops have the equipment to cut an odd-shaped groove to follow the outline of special combustion chambers, particularly heavily modified engines with large valve cutouts. This 440 would work well with regular circular O-ring grooves, either in the heads or the block. The heads are tough to do since there is nothing from which to index or center the cutter, requiring careful measurement to locate the groove position, and of course, careful measurement of the parallelism of the head to the mill. The block is much easier to do, since the groove location can be indexed off the cylinder bores
In fact, in the tool section of the Isky Racing catalog, we saw just the tool for the job: a Groove-O-Matic hand cutter. Though it sounds like a blender to mix new-age fruit drinks, this tool is a serious piece of engine-building equipment. We figured, why deal with a machine shop when we could just pick up an Isky Groove-O-Matic and do the job at home? The tool's not cheap, but we figured if it works, we'd be set forever after. As it turns out, Isky will even rent the tool if you believe your O-ringing career will be a one-shot deal.
Here was the culprit. Too...
Here was the culprit. Too much squeeze, and these cheapo rebuilder's gaskets pushed out like the cheapo composition gaskets they are.
As part of the solution, we...
As part of the solution, we obtained a set of Dead Soft copper gaskets from Milodon. The bore holes in these are cut dead round, while we had machined the head chambers out to near a stock gasket's size to unshroud the 440's big valves; we needed to trim the gaskets to keep from reshrouding the chamber. The part of the gasket that overhangs into the chamber is unsupported by the head and the O-rings pressing up under this area won't do any good.
To make sure the O-ring placement...
To make sure the O-ring placement will be positioned to sandwich the ring between the solid iron top and bottom, the gasket was painted with DyeChem machinist layout fluid. Next, the gasket was doweled in place and any overhanging areas were marked with a scribe.
With the head gasket laid...
With the head gasket laid over the block and held in position by the dowel pins, the Groove-O-Matic's center adjuster was wrenched snug with the bore. The Cobalt cutter was set to an eyeballed .060 inch outside of the scribed edge of the mark farthest out on the gasket surface. With the cutter set to clear this farthest spot, it'll make the groove to the outside of all the chamber cuts. Now take the gasket off and make sure the cutter will make the groove all the way around on solid iron. Setting the depth of this cut is easy. Just shim (sections from a feeler gage will work) the cat paw pins by the depth you want to go and drop the blade flush with the deck. When the shims are removed, the cutter will slice into the block a like amount. Isky recommends making a first cut at .025 inch, followed by a clean-up cut of .005 inch. Though it isn't necessary in cast iron, we used some cutting fluid-which helped make a clean chatter-free groove. Just turn the handles on the Groove-O-Matic and it cuts an accurate O-ring groove.
The depth of the cut can be...
The depth of the cut can be checked by tapping in two short sections of the wire at opposite sides of the bore, and laying a straightedge across it, measuring how much the wire is protruding from the bore. We used the recommended two-pass procedure on the first bore, but figured resetting the cutter twice per bore would likely cause problems with repeating the exact depth. Since we hit the first one exactly where we wanted, we cut the remainder without resetting the cutter.
The O-ring wire taps in with...
The O-ring wire taps in with a slight (.002 inch) interference fit, which holds the wire in the groove. Start at a point where there is the least likelihood of a compression leak (the wire ends will join there), and use a plastic hammer to work the wire into the groove. The wire is cut with a pair of dykes, so that the ends just butt.