Where do you start when trying...
Where do you start when trying for more than three times stock 5.0 power output? Probe begins with its Dominator short-block, which for $1,860 gets you a stock block, a 3.400-inch stroker cast-steel crank, and all the happy stuff connected to it. To handle power pushing the four-digit range, owner Caesar Castro went an extra $2,000 for this stout R302 Ford Racing Performance Parts block with its humongous bearing bulkheads, four-bolt main caps, and extra metal meat everywhere.
If you've been anywhere in the real Mexico-by that we mean away from Cancun and other tourist fleeces-then you know Mexicans are seriously into a good time and don't waste life on bureaucratic nonsense. We can only imagine the high jinks this engine is going to get itself into.
Blower here, stroker there, it's all sort of the same after awhile. Occasionally something different pops up, such as a 347 running on alcohol-in Mexico. The call on this one came from Probe Racing Components in Torrance, California. The company was sort of building, freshening, and upgrading the unusual small-block all at the same time, and calculating its alcohol fuel ought to be good for something unique. We figured a gander over Probe's shoulders would be worth it.
Stroker crankshafts are even...
Stroker crankshafts are even easier to find these days than are stockers. Even for a big-power engine, Probe went with its normal cast-steel 3.400-inch stroker crank for the 347-inch displacement. Probe notes these cranks come off the boat with nitrating, but it added a heat treatment hardening process as well. To reach the required 28-ounce balance, Probe ground off some of the outer circumference of the counterweights. It would have taken drilling big balancing holes otherwise, so clearancing some of the outer counterweights was easier.
Engines such as this are always good for a story anyway. The tale here is the Mexican owner, Caesar Castro, lives in Hermosillo, Sonora, and enjoys participating in local contests of automotive machismo. The rumor is these events take place on barricaded public streets, which we can easily understand given the liquidity of petty local regulations in La Republica. But having not spoken directly with Señor Castro, we're not precisely sure exactly what sort of contests these are. Clearly they require plenty of noise and torque, as Caesar's other engine is a 572-inch 460 stroker-both the big-block and the 347 small-block we're looking at here doing duty in the same '72 Mustang. Given the voracious alcohol consumption of these powerplants, we surmise mano-a-mano drag racing not too far out of town is the duel in question, but you never know.
We can also safely postulate Señor Castro is no small fry. In a place where many citizens are happy the busses continue to operate, he has somewhere approaching $20,000 in this engine, which ought to guide you in your desires to replicate it.
When clearancing a 347 package...
When clearancing a 347 package in the more confining R302 block, there's just that much more metal to grind. Here's the deeper-than-usual 347 rod-bolt-to-cylinder-wall grind job on Caesar's block.
Because alcohol is consumed...
Because alcohol is consumed at just about twice the rate of gasoline, hot-to-trot alky motors can have some fairly serious fuel pumps. These are invariably crankshaft driven, leading to the gilmer belt drive sprocket and extension shown here with Caesar's Romac harmonic damper. These parts previously ran on his Brodix-headed small-block.
Naturally, the connecting...
Naturally, the connecting rods are Probe 5.315-inch, steel H-beam TrackMasters. As with the crankshaft, they are Chinese imports, which explains their low cost. Alcohol fuel explains the rust spots on the beam-the super-clean-running alky is like running an engine on solvent. Parts come out of running engines clean and have a tendency to pick up light surface rust quickly. Clevite 77 H-bearings are used; the H stands for Hard. That means the bearing has a steel shell, a larger fillet radii, and more heat-resistant materials. They are designed for big power engines that can really lay the crank and rods against the caps. Naturally, these cost more than the usual inserts. Rod bolts are ARP 3/8-inch L19 upgrades-good for the 9,000 rpm this engine may see.
In light of the high rpm anticipated,...
In light of the high rpm anticipated, Probe moved down from 0.150-inch piston pins to these 0.120-inch wall units. That's nothing radically lighter, but a little diet for the reciprocating weight without going to short-lived 0.090-inch wall pins as used in engines with 20-run lifespans.
Do we really need to say these...
Do we really need to say these are Probe custom pistons? The moderately tall domes look racy and are needed to get the desirable 14:1 compression, but they aren't the last word in smooth flame front travel. Probe went to a low-tension 0.043-inch Childs & Albert ring package from the more common, but heavier, higher-drag 1/16-inch stuff common on street engines. A little more gap is needed for the hot alcohol burning, and the siamesed R302 cylinders were filed in too. Assembler Roy Baird said he could really feel the lack of drag when rotating the crank on the engine stand. He said it felt like half the torque normally required with 1/16-inch rings.
Everyone has to save money...
Everyone has to save money somewhere, and when you're just having fun with your amigos, popping the big bucks for a dry-sump oiling system is a bit much. Caesar's engine will do its thing with a simple Melling high-volume, high-pressure oil pump and Probe driveshaft.