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Low-Buck Ford Small-Block Stroker EngineAvoid The Belly-Button Curse From the February, 2009 issue of Rod & Custom By Drew Hardin Photography by Drew Hardin
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 Heres where the 302-to-327-stroker...  Heres where the 302-to-327-stroker process beginswith a well-used (but sound) 302 block. JMS preps the block by hot-tanking it, removing all the old gasket material, baking it, and then abrading it with steel shot to make sure its sparkling clean.  When the block is clean, dry,...  When the block is clean, dry, and cool, its magnafluxed to check for cracks. The cylinder walls are potential trouble areas and will be sleeved if cracks are found.  Once the block passes inspection,...  Once the block passes inspection, machining begins. First, the cylinders are bored 0.025-inch over (on their way to a 0.030-inch over-bore). *  Then the decks are squared....  Then the decks are squared. The JMS machinists remove only enough material to make the deck heights evenin this case 0.006 to 0.008 inchas they dont want to lean too hard on the compression ratio. This will be a 9.0:1 motor that can run on pump gas.  A small detail that will help...  A small detail that will help later on: JMS machinist Kevin Ramirez chamfers the tops of the cylinders to make it easier to slip in the pistons during assembly.  The mains are align-honed...  The mains are align-honed to make sure the crankshaft sits square in the block.  The cylinder walls get a finish...  The cylinder walls get a finish hone to achieve the 0.030-inch overbore. Then the block is washed once more before assembly.  Now on to the special stuff....  Now on to the special stuff. Starting with an early 302 crankshaft, JMSs Howard Allen (the father of this stroker design) adds material to the rod journals to increase the stroke from 3.00 to 3.25 inches. He does so through a process called immersion welding, whereby the welding is performed under a stream of flux. This way, no flame or spark is visible, and Allen doesnt have to wear special clothing or eye protection.  Turn off the flux flow during...  Turn off the flux flow during the process and this is what the welded material on the crank looks like. Allen told us he welds only to one side of the journal to minimize the risk of bending the crank. He has spent a lot of time fine-tuning the process, so he knows exactly how much material to add and where on the journal it should go.  To make sure the crank hasnt...  To make sure the crank hasnt flexed during the welding, Allen checks it for straightness once the material is on.  Then the welded crank journals...  Then the welded crank journals are polished to a smooth finish.  There you have it: a 302 stroker...  There you have it: a 302 stroker crank. Slick, no?  The other part of the stroker...  The other part of the stroker equation is a piston/rod assembly thatll work with the new stroke length. Allen figured out that a Ford rod/Chevy 350 piston combo works best, but to get the two parts to meet requires some machining. The Chevy piston pins are just a bit bigger than the Ford rods holes, so the small end has to be bored 0.015 inch to get the two to fit.  The Chevy piston is also just...  The Chevy piston is also just a tad too high, so JMSs Bill Shoemaker cut 0.065 inch of material off the top.  Finally, the pistons...  Finally, the pistons valve-relief pockets need to be recut to clear the Fords valves. The diameter isnt an issue; its the fact that the location of the Ford valves is just different enough from the Chevy application to require material removal.  Once the piston machining...  Once the piston machining is done, the reciprocating assembly is balanced. The rods and pistons are weighed, and the weights of the assemblies are matched.  Then bobweights approximating...  Then bobweights approximating the weights of the pistons and rods are attached to the crank, and Shoemaker spins the crank to find any imbalance. Weight will be added or removed from the crank as needed to balance the assembly.  With all the machining and...  With all the machining and balancing done, the strokers assembly is pretty straightforward. New freeze plugs and cam bearings are installed in the block.  Then the new cam goes into...  Then the new cam goes into place. The grind on the Elgin Pro Stock Performance camshaft is good and streetable: 0.496 lift and 224 degrees duration (at 0.050) on the intake side; 0.517 lift and 234 degrees duration for the exhaust. JMSs owner and founder, Don Johnson, performed the engine assembly, and he offered several tips to engine builders. Among them: When applying moly lube on the camshaft, use only as much as you have to. Any excess lube that winds up in the oil pan will look like metal shavings and scare you unnecessarily.  After setting the crank in...  After setting the crank in the mains, Johnson pressed the rear main seal in place. Then it was time to bolt on the main caps. Another engine-building tip from Johnson: Put a dab of red Permatex on the ends of the rear main cap to avoid oil leaks.  After attaching the Dynagear...  After attaching the Dynagear crank and cam gears and the double-roller timing chain, Johnson degreed the camshaft to make sure everything was in proper alignment. Its probably a waste of time, since Howard puts material on exactly in line with the crank keyway, Johnson says of his exacting crank welder, but well do it anyway. Degreeing the cam is a step JMS performs on all but its most bone-stock motors.  Before he put the piston rings...  Before he put the piston rings on the TRW forged pistons, Johnson measured the endgap of the top piston ring. He also looked the rings over and filed down any burrs. Once the rings were up to snuff, he slid them into the pistons and slipped the pistons and rods into the block.  The only massaging done to...  The only massaging done to the heads is the removal of what Johnson called the smog bump in the exhaust port. Look closely in the port of the stock head on the right and you can see the raised area; notice that its gone from the head on the left. Grinding off the bump reduces torque by about 4 lb-ft, says Johnson, but it adds 15 to 16 horsepower.  We wanted dyno numbers to...  We wanted dyno numbers to see just what the stroker would do, so Johnson and Todd Butts put together a fairly conservative intake/exhaust/ignition combo, in keeping with the motors low-dollar approach: a Holley four-barrel carb, Edelbrock dual-plane manifold, MSD ignition, and 11/2-inch headers.  The heads JMS uses for this...  The heads JMS uses for this stroker engine are either D8OE pieces from a late 302 (which were used here) or D8AE castings from a 351 Windsor. These heads are preferred for their combustion chamber size: 69cc compared to the early 302s 58.2. JMS does very little to the heads; the stock 1.87-inch intake/ 1.54-inch exhaust stainless steel valves are left in place, as are the stock rockers and valve springs.  In a manufacturing quirk that...  In a manufacturing quirk that only FoMoCo could explain, some head castings will use bolt-on rocker arms (like those shown here), while others will have studs for adjustable rockers. Because JMS uses hydraulic lifters in the motor, theres no performance difference between the two. Once Johnson had all the rockers torqued down, the long-block assembly was finished.  Once the motor was fired,...  Once the motor was fired, Butts made several pulls. Though he and Johnson played with the timing some, the first pulls setting of 33 degrees seemed to work best. The 327 produced 293 horses and over 321 lb-ft of torque, with a nice flat torque curve between 2,500 and 4,600 rpm. In a hobby where individuality is king, is there anything more harsh than being branded common? Is there anything worse than carrying the belly-button label? Hardly. Which is why so many of us spend so much time figuring out all the details that will make our rod truly unique. We lay awake at night, assembling our dream project in our minds eye right down to the smallest detail, from the arc of a spreader bar to the pinstriping around the taillights. That being the case, why do so many people choose the single most common enginethe Chevy small-blockwhen it comes time to motivate their street rods? Sure, you can dress it up with all kinds of accessories, from beer-keg-size blowers to zoomy exhaust pipes, but underneath all the doodads, there still beats the heart of the same engine that has powered millions of cars and trucks for almost half a century. Is that really what you want for your one-of-a-kind project? Now, the arguments for Chevy small-block power are pretty strong. Those engines are plentiful and cheap. So are replacement and performance parts for them. They make good power. When looking for an alternative to the Chevy, you usually have to give up at least one, if not many more, of those traits. Flathead? Can be expensive to build properly. Early Hemi? Ditto. Nailhead? Four-banger? Caddy? Not exactly plentiful, and parts can be scarce. So let us suggest an alternative motor that is also plentiful and cheap, and is backed by a wealth of easy-to-find parts: a Ford small-block. Not just any Ford small-block, thougha stroker. You see, stroking a 302-inch Ford solves a couple of its inherent problems. Displacement goes up, and the longer arm is a sure-fire cure for the 302s lack of bottom-end power. Plus, it can be done inexpensively. The folks at JMS Racing Engines in Monrovia, California, have scienced out a 327-inch stroker (designed originally by JMS machinist Howard Allen) so that they can offer it in long-block form for about $3,000. Since there are about as many definitions of long-block as there are engine builders, heres what three large will get you from JMS: the block, reciprocating assembly, timing set, cam, heads, and valvetrain. You provide the rest, custom-tailored to your application. The key to building this motor cost-effectively is in the choice of parts. Theres nothing expensive here. Everything is off the shelf, says JMSs Mike Johnson. Instead of a brand-new block and fancy aluminum heads, JMS uses refurbished blocks and lightly massaged cast-iron heads. The cam grind is streetable; the rocker arms are good old-fashioned stamped steel. Not quite everything is off the shelf. The crankshaft starts out as a stock piece from an early 302 (the most desirable as theyre the most resistant to bending), but, before its set into the mains, its welded with enough material to add ¼-inch to the stroke, its polished, and then its dynamically balanced with the rest of the reciprocating assembly. That assembly, by the way, is an unusual combination of Ford connecting rods and Chevy 350 pistons to get the piston pin height right for the increased stroke. Using the Chevy pistons requires some special machining: The pin hole is enlarged, some material is taken off of the piston top and skirts, and the valve relief pockets are recut. JMS is a machine shop as well as an engine building/testing facility, however, so all this work can be done without the motor ever leaving the premises. Cheap is one thing, but does it make power? Says Johnson, All of these motors put out right around 300 horsepower and never less than 300 lb-ft of torque. Put that kind of power in a lightweight street rod and youll have a real goernot a race car, but one thats certainly fun between the stoplights. Since the JMS engine dyno is just a few footsteps away from the machining and assembly facilities, we thought a couple of pulls would be a good idea to see how close Johnson was with his estimates. For the testing, the long-block was fitted with an out-of-the-box Edelbrock Performer intake mani * fold, a 600-cfm Holley four-barrel carburetor, MSD 6AL ignition, and 1½-inch four-into-one headers. Timing was set at a conservative 33 degrees, and 87-octane pump gas fueled the fire. With barely any fiddling with the tune, the motor churned out 293 peak horses at 5,500 rpm and over 321 lb-ft of torque. Even better, the motor delivered over 310 lb-ft of torque between 2,500 and 4,600 rpm. Youd definitely feel that in the seat of your pants. Good as this motor is as-tested, its also a great starting point for further power gains. JMS tested a similar engine with a 700-cfm carb and made 307 horses and just under 340 lb-ft of torque. If you played with any of a number of factorscam grind, carb size and/or jetting, octane, header-pipe diameter, timing, and so onyoure bound to find more power. Even so, in its most basic configuration, the JMS 327-inch stroker would be a healthy addition to any low-dollar project car, and it would never carry the belly-button stigma.
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JMS Racing Engines
6-26/-357-2718
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