In an effort to stave off...
In an effort to stave off detonation, the piston tops were coated with athermal barrier. The piston skirts were also coated to reduce side-wallfriction.
While the Popular Hot Rodding gang would haveyou believe the EMC competition is all about street motors, the simplefact that they are required to run on 92 octane does not a street enginemake. With few exceptions, none of the EMC entries were destined foractual street use. All of them were built to run right on the raggededge of detonation, something surely not desirable for a street motor.Such things as low-tension ring packages that improve power by reducingfriction are not really designed for high-mileage street use. Asexpected of any serious competition (did we mention the winner receiveda cool $100,000 in contingency cash?), the EMC mills were built with aspecific purpose--to make as much average power as possible throughoutthe test-rpm range without detonating themselves to death in theprocess. The fact that the power curves would be a welcome addition tomost any street (actually, strip, given the 650-700 hp and more than 600lb-ft of torque) machine was actually more of a byproduct.
It shouldalso be mentioned that these EMC powerplants were all a tad on thepricey side. Such things as Dart blocks, custom forged-steel (or billet)cranks, and rods and pistons all begin to add up. Throw in the alwaysnecessary custom machining, the multitude of test components, and thedyno time, and you're into a serious engine for something in theneighborhood of 25 large.
Total Seal provided a set...
Total Seal provided a set of gapless (top) rings to maximize ring sealand to minimize the chance of oil contamination that can accompanylow-tension rings. The last thing we wanted was to introduce oil vaporinto a chamber already running on the ragged edge of detonation.
Despite the single-purpose use of the EMCmotors, we were excited about a venue that promoted the average powerproduction across such a broad range. We began to gather the necessaryparts from our con-glomeration of test pieces. In the stash were anumber of the required components, including a Dart four-bolt Windsorblock, a set of Air Flow Research 225 cylinder heads, and a variety ofdifferent intake manifolds (including our secret weapon in the form ofan Edelbrock Super Victor ported by none other than famed inductionexpert Keith Wilson). After thumbing through the catalog, we went toComp Cams for additional cam advice to narrow down our choices.
Fromthere, we went to Coast High Performance for our reciprocating assemblyneeds. CHP filled the block with a Scat 4340 forged steel crank thatfeatured a 3.825-inch stroke. The stroke was all but dictated by the4.125 bores in the Dart Windsor block. The crank was further tuned(knife-edged and lightened) by the experts at Castillo CrankshaftSpecialists. CHP also supplied a set of 6.0-inch forged connecting rods(small Chevy journals) and forged-aluminum Probe pistons. The piston(dish) design was finalized after digitizing the AFR 225 com-bustionchamber.
This Milodon oil pan and windage...
This Milodon oil pan and windage tray proved to be an impressive upgradeby controlling the amount of oil that came in contact with thecrankshaft. Less windage equaled more power--in our case, upping theaverage score by more than 14 points.
We would eventually further reduce the static compression bymachining the piston dishes, but we started out with a staticcompression of 12.6:1. The CHP/Dart short-block was topped off with aset of out-of-the-box AFR 225 heads and the Keith Wilson Super Victorintake. We installed a Tony Jones SS1 carb (modified Holley Dominator)and a Comp cam that offered 0.688 lift and a 249/253 duration split (at0.050). A set of Hooker Super Comp (5.0 Mustang) headers were added, aswell as a CSI electric water pump, an MSD ignition, and a CHPFox-chassis oil pan.
The 410ci motor was broken-in on the dyno and ranfrom 2,500 rpm to 6,500 rpm on the first of what would be 400-plus dynopulls! After tuning with jets and timing, the 410 eventually producedmore than 650 hp and 585 lb-ft of torque, but more importantly, anaverage score of 961.7 points (average horsepower plus average torquefrom 2,500 rpm to 6,500 rpm). Given that the calculations from theprevious two years told us we needed a score close to 1,020 points, westill had a long way to go.
After running all 30 5.0 heads...
After running all 30 5.0 heads in MM&FF's own Ultimate Guide to CylinderHeads, we felt we had all the information needed to choose the best(legal) cylinder head. The AFR 225 seemed to be the premier inlinecylinder head available for this competition, thanks to impressiveflow-per-port volume. Getting a cylinder to flow big peak numbers isfairly easy, but getting it to do so while retaining impressive low- andmid-lift numbers is more difficult. Achieving this task with thesmallest cross section possible is the key to maximizing average powerproduction from 2,500 rpm to 6,500 rpm. The AFR 225s excelled in allthese areas.
Dropping down in cam duration to a 242/246split resulted in an additional 6.1 points, while adjusting the Jeselbeltdrive was worth another 5.7 points. Replacing the 320-pound (seatpressure) valvesprings with 170-pound Comp Beehive springs was worth 8.7points, and installing a Milodon oil pan and windage tray added 13.7points, bringing the new total up to 996.1 points. We were gettingcloser. More out of curiosity than anything else, we swapped out theSuper Victor for an out-of-the-box Edelbrock Performer RPM Air Gap. Thepeak power dropped by almost 50 hp, but the average power was up by 9.1points. Since the Air Gap was designed for a 351, we knew porting wouldyield big dividends. Extrude Hone porting the RPM intake added awhopping 14.7 points, while adding a 4150-4500 carb spacer added another14.2 points. Fabricating a divider in the open carb spacer was worth 3.2points, and a small notch in the divider added another 1.7 points. Astack of open (Dominator) gas-kets was worth 4.8 points. Now the totalwas up to an amazing 1,043.8 points.
It took endless hours on the dynoscratching to find every last bit of horse-power, but the EMC 410 wasfinally looking like a contender. Naturally, the testing pro-cess wasconsiderably more difficult than the simple points progression wouldhave us believe, as every test was run at 160 degrees water and 190degrees oil. Each combination required running different timing sweepsand may have required changes in jetting to the Tony Jones SS1 carb.
Itwas about this time that we ran into fellow competitor Andy Dunn whilehe was testing his (similar) 410-inch Ford combination at Westech.Unfortunately for Dunn, a rather elevated static compression ratioresulted in damage to a couple of pistons while testing on pump gas.This worried us because we had yet to run any tests on pump gas. Ourthinking was to test everything on race fuel, then slowly dial in thetotal timing to sneak up on the possibility of detonation afterfinalizing the combination. The detonation experienced by Dunn concernedus to the point of disassembling the motor and lowering the staticcompression from 12.60:1 to 11.82:1. While out, the piston tops werecoated with a thermal barrier coating and the sides with an antifrictioncoating. We also took the liberty of coating the Edelbrock Performer RPMAir Gap intake manifold.
The AFR 225s were run as supplied...
The AFR 225s were run as supplied by Air Flow Research, with theexception of hand-polished chambers by the author. The heads weresupplied with 2.08/1.60 stainless steel valves and equipped (by theauthor) with an overkill package that produced 320 pounds of seatpressure--much more than required given the rpm range of the test.
The heads were retained using...
The heads were retained using a set of Fel Pro 1045 head gaskets and ARPhead studs. Neither were ever a concern during testing despite theabuse.
After running the aggressive...
After running the aggressive valvespring package, we swapped in a set ofbeehive springs from Comp Cams and were imme-diately rewarded with anincrease of 8.7 average points. The Comp springs reduced the seatpressure from 320 pounds to 170 pounds with no loss in valve control.
Not surprisingly, we ran a...
Not surprisingly, we ran a number of different cam profiles during themany test sessions. After running two larger cams, we chose a profilefrom Comp that offered 242 degrees of intake duration, 246 degrees ofexhaust duration, and a dual-pattern lift split of 0.672/0.688 with a109-degree lobe-separation angle. The smaller cam reduced the peak powersomewhat, but the all-important average score was up by 6.1 points.
The Jesel adjustable beltdrive...
The Jesel adjustable beltdrive was a valuable tool for dialing in thecam profiles. Without exception, the best average score for each camprofile tested came only after dialing in the Jesel beltdrive. The camresponded best to 1.5 degrees of advance. The adjustable cam sprocket(beltdrive) netted another gain of 5.7 average points.
Along with three cams, we...
Along with three cams, we tried all the different combinations of 1.6and 1.7 ratio rockers. Not many Ford builders were aware of the legalityof the 1.7 ratio rockers on the Windsor, but the EMC rules stated themaximum ratio allowable was 1.6 unless a larger ratio was available fromthe factory. Naturally, the Cleveland could use 1.7, but so too couldthe Windsor since Ford offered 1.7 rockers on the 5.0 Cobras.