Fords overhead cam design on its 2,300cc motors should let us spin this baby up to 8,000rpm regularly without fear of meltdown. |
Fit is everything. Tim Yates triple checks tolerances for every piece to make sure its all within the prescribed tolerances. Were looking for .0025 between the bearings and crank journals. |
If you remove the bearings after prefitting the engine, make sure to mark each one so it returns back to its original position in final assembly. |
Race Engineerings long rod/short piston combination means the wristpin hole extends into the groove for the oil ring. To prevent rotation of the oil ring spacer, it has a small dimple that must be placed in the opening facing down to prevent the ring gap from settling in the hole. |
The crank must have a certain amount of endplay, but Race Engineering likes to limit it to no more than .007 at the thrust bearing. |
As you can see from the interior of our oil pan, oil control is a serious matter at C-Line Engineering. |
Yates welds metal straps over the holes in the top of the cam towers to make the Ford head capable of withstanding racing stresses. |
Machining on the exhaust port is complete, while the intake has yet to be touched. In addition to cleaning up the bowl and machining the valve seats, the wall of the combustion chamber next to the exhaust valve has also been moved back to allow better airflow. These same steps will also be done to the intake. |
Blending is allowed 3/4 of an inch into the ports measured from the top of the valve seats. Good work here can make a big difference in an engines performancethis is where Yates earns his keep. |
Almost every thousandth available is machined off our head. The intake studs were screwed into place before decking the headthe head is shaved so thin its possible to crack the metal from the torque if the studs are screwed in afterward. |
Decking the head almost closes off this oil galley that runs between the block and the head and sends lubrication to the cam. Yates opens it back up to allow good, clean flow. |
Yates prefits the overhead cam. Dont even think about asking for Johnsons cam specs. |
Yates finds the correct valve-stem height by shaving them gradually until they provide .500 lift with no lash. |
Valve lash is dialed in at .010 for the intake and .012 for the exhaust. Johnsons Machine uses extra long adjuster studs to keep more threads in the lifter bores after the valves are adjusted. |
Once the head is bolted on the block, a little break-in lube is the last step before buttoning everything up. |
Richard Johnson (left) and Tim Yates stand with their latest creation, a little muscle for Project Mudslinger. |
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Weve all heard big things often come in small packages. Yes, we know its a cliché about as old and tired as Grandmas mint-green Buick grocery-getter, but there is a kernel of truth to it. In the case of the Project Mudslinger, every cubic centimeter of engine displacement means one pound toward the cars total weight. You can overstroke a four cylinder to come up with gobs of thrust, but it does no good if the weight penalty makes it impossible for you to turn in the corners. Needless to say, we are looking for big power in a small package.
Race Engineering and Johnsons Machine Shop have been wrestling with this problem for years, and the two companies have teamed up to produce some pretty vicious four-bangers (see our stroked four cylinder buildup, Supersize It!, in the Feb. 2001 issue, or go to www.circletrack.com). They agreed to assist us in our quest for speed and even to let Circle Track follow along to show you exactly whats going on inside our little black powerplant.
Race Engineering specializes in the short-block, and Johnsons Machine builds the heads, complete with overhead cam. Race Engineering normally ships its short-blocks assembled, but for our project Tim Yates, Johnsons head engine builder, is handling all the engine assembly at Johnsons shop in South Carolina. Our block is a 2.3 liter that originally lived in either a Ford Mustang or Ranger pickup. It has been bored .030 inches over, align honed and machined to zero deck the pistons. Total displacement will be 2,340cc. Rules state the crank also has to be a stock piece, but thats about all. Race Engineering takes advantage of that by shaving approximately three pounds off the counterweights. Three pounds may not sound like much at first, but its a ton in terms of rotating weight and drastically improves acceleration. After balancing, our crank now weighs in at a svelte 28 pounds. 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 prefitted, complete with bearings, and thoroughly checked for proper clearances. Yates says Johnsons and Race Engineering recommend .0025-.0028 clearance between the main bearings and the crank and also .007 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. Because the wristpin hole extends into the oil groove a spacer is supplied to support the oil ring. The first ring is gapped to .012, and the second is gapped to .010. Main caps are bolted in at 85 pounds, while the rod bolts are torqued to 50both with 30 weight motor oil.
The bottom end is buttoned up with an oil-pump snorkel and pan from C-Line Engineering. C-Line makes some fantastic products for Late Model race cars and recently put all its engineering tricks into this oil pan for Ford four-cylinder engines. Its deep with a wide sump to move oil away from the crank and has more gates than a compound filled with militant separatists. The custom snorkel has a wide mouth and is cut to pull oil from the very bottom of the pan. Richard Johnson, owner of Johnsons Machine Shop, estimates this pan adds seven horsepower over the stock unit on a dyno. Hes sure the actual number is even higher when the oil is sloshing around in the pan during a race.
Rules for our Mod Four class require the head be stock, but they do allow the head to be converted from hydraulic to solid lifters. Since this is an overhead cam engine, there is a lot of power to be found here. In addition to converting to solid lifters, we are also allowed to cut inside the bowl on a diameter smaller than the valve seats and perpendicular to the valve stem. We can also blend on any angle up to ¾ of an inch from the top of the valve seats.
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 into place, the extra stresses caused by racing can crack the towers. After Yates finishes grinding his welds smooth, you can hardly tell anything has been done.
To convert from hydraulic to solid lifters, Johnsons has lifter bore sleeves and adjuster studs specially made to its specifications. The sleeves are designed with .003 crush to really lock them in place. Richard has found that this works better than the more standard knurled inserts. The adjuster studs are also longer than the ones many engine builders use to keep more threads in the insert after adjusting valve lash. Conversion from hydraulic to solid also requires shaving .350 off the top of each of the bores.
Next, the head moves over to the valve seat machine for a series of cuts. First, Yates opens up the valve guides so new bronze guide sleeves can be inserted. Then the valve seats are cut with a tool that does all three angles at once. Yates is careful to cut no more than necessary; keeping the cut shallow minimizes the depth of the combustion chamber. Finally, the interior of the bowl and the side of the combustion chamber next to the valve are cleaned up to improve airflow.
Unlike many Late Model series, our Mod Four rules have no requirement for minimum combustion chamber size. This allows Johnson to pick the compression he feels the engine needs and deck the head until he gets it. The goal for our engine is 12.3:1, which translates to 42cc combustion chambers. Yates has to take a total of .170 off the head on an angle to get there (on this head every .007 cut equals one cubic centimeter removed from combustion chamber).
Finally, its time for assembly. Yates triple-checks the stainless steel valves against the seats then installs the cam. Johnson has his cams ground to his own specs, and the CIA is more lenient with its secrets than Johnson about his cams, so dont even bother asking. All we know is lift for both the intake and exhaust is .500. Yates grinds the valve stems so they lift .500 with no lash, then sets the adjuster studs to .010 lash in the intake and .012 on the exhaust before locking everything down. We are using single valvesprings with a height of 1.625 to 1.650 inches and have 250 pounds of pressure compressed.
Johnsons Machine completed the package with a set of Race Engineering pulleys and belts that are about as light as they come. Firepower comes via a distributor and coil from Mels Ignition. (You can read more about Mels innovations for four-cylinder engines in A Simpler Spark in the July 2001 Circle Track.) We are also using a racing-specific water pump from MPR Inc., which has a roller bearing and a backing plate over the impeller to prevent cavitation.
Were pretty happy with our little beast of a powerplant. Johnson recommends we run it all the way up between 7,800 and 8,000rpm, which is possible thanks to the overhead valve design. We plan to feed everything with a Keith Dorton Series, Holley two-barrel carburetor (PN 80583-1). This 500cfm carb is based on Holleys 4412 model with some really nice tweaks to make it competitive right out of the box with a high-end piece from a carburetor tuner. Now all we have to do is get in gear with the car and see how it all works togethereasier said than done!
Part I: In the Beginning There Was...Junk
Part II: All Caged In
Part III: Shoehorn, Please!
Part IV: Toil And Trouble
Part V: What Do You Mean, Start Over?