David Vizard
May 1, 2003

Step By Step

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The APT Wire Wizard, which puts all the plug cables in the same order as the cylinders, added the finishing touches to this 392-inch RDI custom crate motor. With looks matching its performance, this torque monster delivered 515 lb-ft of torque and 504 totally streetable horsepower.
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Preston Miller and one of his custom crate motors. This one is destined for a well-known and prestigious Cobra kit manufacturer.
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Here are the factors necessary to optimize so as to make the most of a cam selection: 1) Intake lobe lift. 2 ) Intake lobe flank, indicated is the opening but the same applies to the closing side. 3) Intake opening duration. 4) Exhaust lobe lift. 5) Exhaust lobe flank. 6) Exhaust opening duration. 7) Lobe Centerline Angle (LCA). 8) Direction of adjustment for advance and retard. 9) Overlap. The rockers also play a significant roll and affect the final cam events required. For instance using a higher ratio rocker on the intake alters the required LCA for optimum performance.
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Used extensively on Winston Cup engines, the ATI Super Damper was chosen as a proven piece to aid longevity of the crank and increase power by reducing the negative effects of torsionals on the cam events.
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Canfields heads were used because of the appropriate port size for the displacement used and the good out-of-the-box flow figures. Equipping it were Ferrea valves, Isky adjustable pushrod guide plates, and Comp Cams beehive springs with titanium retainers.
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As received from Canfield the seats were intended for use with 2.02 intake valves. The RDI Street Pro was going to use Ferrea 2.05/1.6 valves so the seats were cut accordingly.
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Valves installed and ready to go. The Canfield heads come stock with the chambers CNC machined as seen here.
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Here is the finished seat job. Also note the smooth form and finish of the ports. This is part of the reason these Canfields flow well for a relatively small port.
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The Canfield heads were put through a battery of tests on the flow bench. This included flow, swirl, and port velocity measurements. The results were good in every category.
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Flow is shown by the darker curves. Port velocity is indicated by the upper light colored curves, and swirl by the lower light colored curve. At the 600 thousandths it would be lifted to the intake valve passed some 265 cfm on an accurately calibrated bench. No measurable swirl existed until some 350 thousandths lift, but after that it came on strong. The indications here is the Canfield heads will favor a higher lift as it will help low-end as well as top-end power. At the valve lift to be used the swirl was significantly better than most Ford heads, aftermarket on not. Intake port velocity was also good. For an 'as-cast' port the exhaust showed excellent results throughout the lift range and delivered 182 cfm at the 550 thousandths full lift to be used. Also worthy of note is the exhaust ports excellent velocity. This is a major factor toward countering low-speed reversion. As well as a healthy top end, good low speed performance was expected from these heads and that is just what we got.
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The Probe pistons were light and well made. As a stock feature these pistons have valve cutouts for both conventional valve position heads as per the Canfields being used and TFS Twisted Wedge heads.
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At its asking price the Scat 4340 H-beam rods are a bargain. Additionally it appears some attention has been paid to trimming excess weight from non- critical areas and, as a result, the rod is measurably lighter than most of it's competitors.
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This is the heart of the 392 stroker, a Scat cast steel 3.850 stroke crankshaft. These cranks are ground on the same machines as the cranks that Scat make for Winston Cup and Top Fuel dragster applications.
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Here the RDI custom crate motor block is being treated to a 4.030- inch bore. The boring machine indexes off the mains to ensure the required alignment is accurate.
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Because the 392 Street Pro's bottom-end assembly was close to what Scat envisaged as a typical rod and piston weight the crank needed only marginal drilling to get it to perfect balance.
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The ATI Super Damper was equipped with the required 28-ounce-per-inch balance offset for the stroker Windsor application.
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The Total Seal gapless top ring has one ring nested within the other to provide an effective 100 percent sealing capability. Our tests show this ring seals so well the second compression ring can be dispensed with if an oil control ring is used that can handle the full oil control function on it's own.
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To make the compression/leak down comparison with the Total Seal Rings the conventional rings were meticulously gapped at two-thousandths above what we know to be the minimum before ring end butting occurs. When that happens the top of the piston usually comes off.
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Selective assembly at this point meant each rod, piston, and bearing set where now assigned to a bore. This selective assembly produced tight control over piston to wall and bearing clearances.
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Once all the clearances were established the final assembly could be started. Here the bearings are being installed and coated with an assembly lube.
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When installing the rear main seal (arrowed) it is advisable to smear oil on the seal and the crank surface it runs on.
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End float on the crank was right on the five-thousandths called for on the build sheet.
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With just the right size chamfer on the top of the block the Probe Pistons and Total Seal rings installed easily and smoothly with a regular ring compressor.
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If an engine build is to be successful the selection of the right cam for the job (as opposed to "a cam") is critical. The wrong choice here will easily cost 30 lb-ft and 30 hp, which will just about negate the potential of the extra cubes a stroker crank delivers.
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Motor Machine & Supply's cam guru, Denny Wyckoff, modeled the project motor on Cam Master. This unique cam-computing program eliminates the need to dyno test a multiplicity of cams to get the right one for the job. What it means is the average hot rodder can for $40 get the same results as Bob Glidden and $20,000 worth of cams and dyno time.
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A Comp Cams multi-keyway roller chain sprocket set was used to handle the cam timing chores. This allowed the Comp Cams camshaft to be timed in to better than 1 degree of the spec required.

Blend your specific street/strip performance needs with Winston Cup, Busch GN, and a healthy dose of state-of-the-art technology and what do you get? Pedigree and power well beyond what might normally be expected of a typical crate motor. Working from the geographic center of Winston Cup country, I teamed with Raceparts Distribution Inc. (RDI) and got involved with what is probably the next generation of crate motors.

The target was a totally streetable engine that could not only do sterling service (if called upon to do so) in a heavy working truck, and win at the dragstrip. Was this goal achieved? Well, 504 hp and 515 lb-ft of stump-pulling torque with big numbers right off a 650-rpm, glass-smooth idle from a 392 inch, 9.5:1 compression, fuel-efficient motor says absolutely yes.

Whether or not you are in the market for a super crate motor, follow along and learn some engine building and parts selection moves guaranteed to boost the output of your next street or strip powerplant

Concept
Since its beginnings in the '80s, the factory crate motor programs have allowed many hot rodders to purchase what can only be described as an excellent value for the powerplant provided. But value though it may be, you should not lose sight of the fact it is nothing more than an amalgam of mostly stock parts assembled on a production line. The parts that make up a typical crate motor are usually selected from whatever production parts are thought to be best for the application.

Although this doesn't look like a negative, consider all production parts are primarily designed to meet emissions and high-reliability standards at a low cost. This and mass production is how crate motors can be offered at such reasonable prices for the power and parts obtained. However, the inescapable bottom line here is auto manufactures do not specialize in power--the aftermarket does.

For 14 years Preston Miller was Ford Racing's NASCAR program manager and a Winston Cup liaison engineer. To be successful in this position (and events strongly indicate he was) required a broad range of engineering know-how, an innovative mind, and the ability to overcome the not-invented-here syndrome. Preston now runs RDI, a company he set up to service the hardcore needs of racers, Winston Cup or otherwise. RDI sells Ford's line of crate motors and as Preston points out, they do represent great value for the entry or near entry-level hot rodder.

"But the market," he says, "is getting more sophisticated, and there is a growing demand for a more technically advanced crate motor. At RDI we are in an excellent position to blend value and up-to-the-minute power technology. This is how our custom crate motor program came into being."

The commonly accepted definition of a crate motor is a selected collection of parts that will produce cost-effective results. Part of the cost-cutting deal is the factory produces them by the hundreds if not thousands. Just how power orientated these parts are varies considerably.

Take for instance pistons, cranks, and rods. Replacing the best factory components with the ultimate race ones here won't produce much of an increase. The same can't be said for other parts. Let's consider the cam. Most crate motors use a factory cam, its primary priority is to meet emissions and other such "strictly street" requirements. Take a cam of the same duration (note: same duration) intended to prioritize power and we see the output of the crate motor come in for what is potentially a big change in the upward direction.

What RDI's custom program does is pick on a crate motor's weakest links and fix them. This not only allows tailoring more toward the customers needs, but also focuses on the most cost-effective upgrades first.

The process of ordering a custom crate motor from RDI starts with the customer calling in with a basic game plan of what they want. By discussing it with RDI's engine councelor, a basic spec of motor and a price is arrived at. This basic spec then goes to a high-caliber engine builder who builds race-winning engines in the upper classes of oval-track racing. The engine builder then refines the spec to more precisely meet the customer's needs and if the customer approves this spec the build begins.

With a dyno facility coming on line for me in a few months, I needed to start collecting good solid dyno test units and time limited the number of motors I can build. I also had a number of project cars in the sidelines that were being built to showcase not only motors, but also all the other components going in to make a fast car. I had a need for a Windsor at the increasingly popular size of 392 inches and approached Preston with some very specific requirements to see if RDI could fill the bill.

To show readers what the potential was for a true and totally streetable application (MM&FF code name "Street Pro"), a pump gas motor having a 650-rpm/15-inch vacuum idle was needed. Not only were good idle characteristics called for, but also stout torque (375 lb-ft or better) was required right off idle. This had to be achieved with peaks no-less-than 485 lb-ft and 485 hp (at about 5,500-5,700 rpm) if the dragstrip performance goals were to be met.

Along with this, mileage had to be good in case the motor ever went into a racecar tow truck. As if all that was not enough, I also needed this motor to be able to deal with as many as 3,000 meaningful dyno pulls, or about the equivalent to 10 weeks of continuous dyno testing, which is real hard on a motor. This meant not only total reliability, but also a spec that would deliver good pull-to-pull repeatability. Without reasonable repeatability a motor is next to useless as a dyno mule.

I pitched my requirements to Preston over the phone and imagined sweat generated by my demands running down his brows. "At RDI we are just shy of performing miracles, but yes, we can do pretty much what you are looking for here." So the wheels of industry clunked into gear and things began to happen.

Motor Spec
After all the factors involved had been duly considered, starting from top to bottom, the build spec was arrived upon. Carburetion was to be by way of one of Barry Grants bigger Demon units. For an intake manifold a Ford Racing/Edelbrock Victor Jr. would be used. The induction system would feed into a set of out-of-the-box Canfield heads. The valvetrain, by Comp Cams, would be a hydraulic roller with the cam events spec'd out by Motor Machine & Supply's unique cam computation program. This program has the capability to produce the optimum cam events specifically for the motor in question first-time around, thus eliminating the need to flog cams to find the best.

Ignition, for shear simplicity and proven performance, was to be a Ford-adapted GM HEI distributor courtesy of Performance Distributors. Combustion products would exit the engine via a set of 1 3/4-inch MAC headers designed to use on a 351 in a Fox chassis. The bottom end would be based on a Ford Racing block and be equipped with Probe pistons, a Scat cast steel 3.85 stroke crank, and forged H-beam rods.

One of the key factors toward maintaining reliability, especially when shaking the crank with over 500 horses and a healthy shot of nitrous, is torsional damping. Here we planned to go the extra mile and actually measure crank torsionals and then have our ATI damper specifically tuned to minimize crank vibration on the combination. And right at the bottom to keep all the oil where it should be when going down the strip, a Canton pan and pickup was to be used.

The Heads
Some very interesting induction tests were done while dyno testing the Street Pro motor so I will detail induction in the next issue. For now let's move right onto the justification for use of the Canfield heads. The principle reason for going with Canfield heads is they have cast ports that flow well by virtue of an efficient form rather than a large cross sectional area. The strong overall flow characteristics give them the potential for good top end while the smaller-than-average volume (for the flow delivered) means good low-speed manners.

Because of the ports generally efficient form, they tend to produce peak power at a higher mean port velocity than many out-of-the-box heads on the market. The typical for an as-cast factory head is around 280 with good aftermarket pieces running about 305-315 ft/sec. Experience with Canfield heads under near ideal conditions has shown peak power occurring at as high as 325 ft/sec. Throwing this number and the heads 193cc intake port volume into a simple computer program indicated the 392 Street Pro motor would hit peak power and torque at 5,611 and 4,320 rpm respectively. This looked to effectively target the 5,500-5,700 rpm peak power called for.

We got the heads from Canfield less the valve job so it could be done to best suit the Ferrea heavy duty valves that were intended to go into these heads. After a precision valve-seat job, I flowed the heads on my bench. The intake and exhaust both produced commendable results.

Also shown in Figure 1 are the swirl figures for the intake and the often talked about, but never shown, port velocities for both the intake and exhaust. I would like to have seen the swirl come on sooner in the lift range, but once it did start the swirl was strong. I suspected that good intake-port velocity, because of the larger cylinder it was to feed, would compensate for any possible shortfall of low lift swirl.

Also of note was the excellent velocity (for an as-cast head) exhibited by the exhaust port. High exhaust-port velocity contributes considerably to good low-speed output and high-speed scavenging. This port promised good all-round performance and, as subsequent dyno testing was to prove, it delivered.

Block Assembly
For the Street Pro a new Ford Sportsman block was used. This was bored to take a set of .030-inch over pistons from Chris Huff's Coast high Performance/Probe industries. These were a dished design to produce 9.5:1 CR with the Canfields uncut. The pistons also had a second set of valve cutouts so as to allow us to test some TFS Twisted Wedge heads at a later date. These pistons were light and tough enough to stand the punishment a typical single-stage nitrous system would dish out.

Complementing the pistons was a set of Scat H-beam rods and a cast steel stroker crank. An option here would be to go for a 4340 forged steel crank. However, I have run a number of Scat cast steel stroker cranks in Chevy road-race motors at power levels up to 565 hp and 7,500 rpm. One of my motors running in England now has three successful seasons on it and has yet to be torn down for any reason. The bottom line is, I am comfortable with the Scat cranks, which are ground on exactly the same machines in Scat's California plant as the Winston Cup and Top Fuel cranks they make. The same can't be said for some of the other brands of cast steel cranks.

Balancing the assembly was straightforward with the flexplate and dampers having the required 28-ounce/inch external balance. The combination of parts was close to the design parameters that Scat envisaged so very little drilling of the crank was required to bring the assembly into balance.

After a meticulous cleaning of all the components involved the short-block components were readied for assembly. This involved far more than simply putting the parts together and here we find one of the major distinguishing features of RDI's Custom Crate motor as apposed to a factory one. Before any final assembly, each part is measured to establish that it is the correct size and all the clearances called for are going to be met. For a shop that puts together $40,000-plus race engines, such parts inspection is a regular routine. One aspect of assembly was far from routine concerned the rings to be used. To date, my engine building friends and I have had very good results in terms of the power expected from a given combination, excellent compression, and leak down numbers. These results have been so good that none of us has ever done any back-to-back testing to establish the degree of superiority the Total Seal rings appear to deliver. I planned to at least make a start on that. One of the 392's first jobs as a dyno mule was to test cylinder seal and compression at the end of what proved to be close to a weeks testing.

Normally the motor would be assembled with eight Total Seal top rings, but on this occasion four cylinders were to have meticulously gapped regular rings and the remaining four the Total Seal rings. The idea was after the first week on the dyno the compression and sealing capability of the regular, versus the Total Seal rings would be tested to establish how each fared under identical conditions.

With the rings, pistons, and rods assembled it was now time to install the rotating assembly into the block. All the dimensional checks that had been carried out on the block, crank, and bearings had already established the clearances that would exist. Any bearing clearances that did not fall between the closer tolerances than a stock build were remedied by bearing shell selection. This type of meticulous assembly is just one more example of the difference between a regular crate motor and what we are dealing with here.

With the crank installed and the end float checked and okayed it was time to install the pistons and rods. At this point we could do the first check to see how freely the assembly turned over. Long-stroke engines have greater potential for piston-to-cylinder wall frictional losses. This means greater attention has to be paid to the accuracy of the parts (absence of any rod twist, etc.) and the ring, piston, and bore finishes. A typical 392 short-block assembled as per a production line requires some 25-30 lb-ft of torque to start the crank, rods, and pistons turning. This RDI unit took just under 18 lb-ft.

Cam and Valvetrain
With all its involvement in Winston Cup it is hardly surprising RDI recommend Comp Cams for the valvetrains of most of their custom motors. Here it was expected that a hydraulic roller of relatively short duration would be used. At this point we were in a position to make a decision on one of the most important aspects of a successful engine build, namely the timing of valve events by the camshaft. The best flowing heads in the world won't deliver their full potential if the opening and closing of the valves happen at the wrong moment.

The usual technique to get the right valve events is to take your best guess and grind that and a number of other cams either side of it, then test for results. If you are good you can hit a near optimal cam in three to maybe five goes and a couple of days of testing. Another alternative is to simply run with an experienced person's best guess. The first is, too, costly for most of us, and the second, depending on whose guess it was, can be considerably less than optimal.

But there is a third option which an increasing number of Pro engine builders are turning to, namely selection through computer modeling. Currently the only place to offer this is through Motor Machine & Supply in Tucson, Arizona. The one-of-a-kind, million- dollar Cam Master program will, given the flow figures of the heads and a number of other factors, compute the cam required.

How accurate is it? About as accurate as having unlimited dyno time and unlimited access to whatever cams are needed. Going the dyno/multiple cam test route would cost a minimum of about $1,000 to over $20,000 and takes anywhere between a day and a month, or so. With Motor Machines computation method you get the answers in 20 minutes or less and all for $40! I suspect anyone with an IQ of 80 or more would figure out which way would be the fastest and easiest route to optimizing the cam events here.

The flow figures, bore, stroke, rod length, CR, and all the other figures required were fed to Motor Machines cam guru, Denny Wyckoff. The specs even take into account how much the nitrous was to be biased toward with or without operation. Here I elected to take a middle of the road course and had the cam spec'd about 15 percent in favor of the nitrous. This would mean a small drop in output (an estimated 5-8 hp) while the nitrous was not in operation but about a 15-20 hp increase when it was.

The computed cam spec used a pair of CC Xtreme Energy hydraulic profiles having duration figures of 274 (seat) 224 (@ .050) for the intake and 282 (seat) 232 (@ .050) for the exhaust. This was ground on a 108 LCA and was to go with 5-degrees advance. The intake rockers called for was to be 1.7 with 1.6 on the exhaust. This gave theoretical lift figures of 590 and 565 thousandths for the intake and exhaust respectively.

Not to keep you in suspense until next month, let me tell you this Motor Machine spec'd grind out performed, in round terms, like an off the shelf CC Xtreme cam having 8 degrees more duration, by about a 30 lb-ft 30hp margin. Of course, to get the cam to work as intended it has to be timed in right. One more step not seen with a regular crate motor.

After installing the cam the rest of the bottom end was attended to. First the stock volume (if clearances are right a high-volume pump is a step backwards) oil pump was adjusted to deliver 60-psi hot.

Since this motor was to be used extensively on the dragstrip an appropriate pan was needed. Here one of Canton's drag race Fox-body 351 Windsor pans was selected. Why Canton? Simple, its products are well respected among pro engine builders because they deliver results. Our pan was an off-the-shelf model and the oil scraper intended for a stock stroke motor. This meant a little clearancing of the crank scraper was required, but this only took 15 minutes or so to accomplish. The last move on the bottom end was to install the ATI damper. This must not be done with a hammer, as is so often the case with the installation of a stock damper. A special tool to pull the damper on must be used and the crank bolt tightened to the appropriate spec. Damper fit and bolt torque are critical to the successful operation of the damper.

Heads and Valvetrain Install
The Canfield heads were installed using FelPro gaskets and ARP bolts torqued to the appropriate figure. Note from the nearby photos that Comp beehive springs and titanium retainers were used as part of our advanced valvetrain. This dropped the same amount of mass out of the valvetrain as would have been the case if titanium valves had been used. Next on the agenda was to install pushrod guide plates. Here something of a component-matching situation can arise. Depending on the heads and rockers used the rockers may not be properly aligned over the valve tips and may hang off one side or another. So it is a good idea to go straight to the Isky adjustable guide plates and be done with it. This allows precise positioning of the middle of the roller on the end of the valve. Next a check on pushrod length was made to see if the rockers roller tip followed the correct sweep on the valve tip. As it happened it was, but it was a situation by no means guaranteed.

Next the valvetrain was finished by being installed and adjusted. This left the intake manifold to be installed. Again, the assembly procedure went smoother than is often the case. Normally some port matching is called for to get the intake manifold suitably aligned with the ports in the heads. This is yet another job not normally done with a regular crate motor. As it happed, the ports in both these components aligned very well and needed no further work.

Ignition & Carburetion
For a distributor, something a little different to the norm was used. Based on years of success with Performance Distributors products, I elected to use its GM HEI adaptation for Ford motors. This unit produces a very powerful spark along with minimal spark scatter for precise timing. In addition to this, it is a totally self-contained unit with a one-wire hookup. The actual model used was the race/dyno unit. This has the position normally occupied by the vacuum advance canister occupied instead by a micro timing adjuster. Half a turn on the micro timing adjuster knob adjusts the timing by about a 1/3 of a degree. After dyno testing I was very thankful for this little function, but more on that next month.

What we planned was something a little different. The logic involved goes like this: The guys running Winston Cup have reworked Holleys that might be expected to be about as near the ultimate in V-8 carburetion as any seen on the face of the planet. These WC carbs also cost an arm and a leg, or two. Prices of $1,200-1,400 are common, but I have heard whispers of as much as $4,000. The intent was to run one of these super Holleys on the 392 Street Pro and calibrate it until every single hp and lb-ft had been wrung out of it. At that point an out-of-the-box, $523, 850 Demon carb would be installed and likewise calibrated to see how it compared to the hopped up Holley.

With the addition of the carb our 392 custom crate motor was about done. How much did all this good stuff cost? In our case about double the cost of a regular crate motor (about $10,500), but it could have been done for a lot less if we had forgone some of the reliability enhancing features such as the Sportsman block.

To see the true worth of this motor I suggest you catch next month's issue, and see how this it fared on one of Charlotte's successful Busch Grand National engine builder's dyno, not only in terms of peak power and torque, but also fuel efficiency and crank torsionals.