Ford's single overhead camshaft...
Ford's single overhead camshaft design on its 2.3L engines and the assembly techniques and modifications from Johnson's Machine should let us regularly spin this powerplant to a useable 8,000 rpm without fear of breaking.
For our Project Mini Stock, we're looking for impressive power from a small package. We only have 2.3L of Ford engine to use, so we went to a couple of pros with experience extracting power from this unit.
Race Engineering and Johnson's Machine Shop have teamed up to produce some vicious four-bangers. They agreed to assist us in our quest for speed and reliability. Race Engineering specializes in the short-block, and Johnson's Machine builds the heads, complete with overhead camshaft and all valvetrain components. Race Engineering normally ships its short-blocks assembled, but for our project, Tim Yates, Johnson's head engine builder, is handling all the engine assembly at Johnson's shop in South Carolina.
Our block originally lived in either a Ford Mustang or Ranger pickup. It has been bored 0.030 inches over, align-honed, and machined to zero-deck the pistons. Total displacement will be 2,340 cc.
Our rules state the crankshaft also has to be a stock piece, but that's about all. Race Engineering takes advantage of that rule by shaving approximately three pounds off the counterweights. Three pounds may not sound like much at first, but it's a ton in terms of rotating mass and drastically improves acceleration of the reciprocating parts. After balancing, our crank now weighs in at a svelte 28 pounds.
Fit is everything. Tim Yates...
Fit is everything. Tim Yates triple checks tolerances for every piece to make sure it's all within the prescribed tolerances. We're looking for 0.0025 inch between the bearings and crank journals.
Both the block and crank are baked at 700 degrees in a special oven and shot-peened, both to strengthen the metal and thoroughly clean it after years of road use. Before our Race Engineering Pro rods and Wiseco pistons are installed, everything is pre-fitted, complete with bearings, and thoroughly checked for proper clearances. Yates says Johnson's and Race Engineering recommend 0.0025-0.0028-inch clearance between the main bearings and the crank, and also 0.007-inch endplay.
Once everything checks out, final assembly can begin on our short-block. Our 5.7-inch rods are fitted to a special set of Wiseco pistons made for this long rod. Because the wristpin hole extends into the oil ring groove, a "spacer ring" is supplied to support the oil ring. The first ring is gapped to 0.012-inch, and the second is gapped to 0.010-inch. Main caps are bolted on at 85 ft-lb, while the rod bolts are torqued to 50 ft-lb-both with 30 weight motor oil lubing their threads.
The bottom end is buttoned up with an oil-pump snorkel and pan from C-Line Engineering. It's deep with a wide sump to move oil away from the crank, and the custom snorkel has a wide mouth and is cut to pull oil from the very bottom of the pan. Richard Johnson, owner of Johnson's Machine Shop, estimates this pan adds 7 hp over the stock unit on a dyno. He's sure the actual number is even higher when the oil is sloshing around in the pan during a race.
Race Engineering's long rod/short...
Race Engineering's long rod/short piston combination means the wristpin hole extends into the groove for the oil ring. To prevent the oil ring spacer from rotating, it has a small dimple that must be placed in the opening facing down to prevent the ring gap from settling in the hole.
Rules for our Mod Four class require the cylinder head to be stock, but allow other engine changes. We are allowed to convert the valvetrain from hydraulic to solid lifters. In addition to this, we are allowed to cut inside the valve bowl on a diameter smaller than the valve seats and perpendicular to the valve stem. We can also blend on any angle up to 3/4 inch from the top of the valve seats. There's stability at high rpm and horsepower in these mods.
But before Yates does any of that, he strengthens the head by welding metal straps to the top of the cam towers. If these straps are not welded in, the extra stresses and rpm caused by racing can crack the four stock towers. After Yates finishes grinding his welds smooth, you can hardly tell anything has been done.
To convert from hydraulic to solid lifters, Johnson's has lifter bore sleeves and adjuster studs specially made to their specifications. The sleeves are designed with 0.003-inch crush to really lock them in place. Johnson has found that this works better than the standard knurled inserts. The adjuster studs are also longer to keep more threads in the insert after adjusting valve lash. Conversion from hydraulic to solid also requires shaving 0.350-inch off the top of each of the lifter bores.