Once upon a time, the 383 big-block Mopar engine got very little respect. It was standard equipment in the legendary Road Runners and Super Bees of the late '60s, early '70s, and was found under the hood of many other Mopar musclecars, including A-Body 'Cudas and Darts. Sure, it was overshadowed by the massive 440 and not in the same league as the 426 Street Hemi, but it was a reliable, powerful, and a less expensive alternative to both. If you wanted big-block power and were on a budget, the 383 was attractive to a lot of buyers. And why not? It had loads of torque and offered a wonderful bore-stroke ratio (4.25x3.38 inches). With the right aftermarket cam and some induction and exhaust mods, it could be a high-winding screamer.
Hundreds of thousands of Dodges, Plymouths, and Chryslers were propelled by this plant before it was replaced by the 400, but today it's an under-appreciated marvel. When a 383 gets tired, it seems like no one thinks twice about replacing it with a 440, a stroked 440, or for the bucks-up enthusiast, a Hemi. Even the 400 gets more respect. Stroker kits that increase its displacement to 451 and 500 ci have been around awhile, and are becoming more and more popular. The downside, however, is that 400 blocks are getting scarce and, correspondingly, more expensive.
Now let's see a show of hands: How many of you have a derelict 383 (short- or long-block) sitting in the corner of your garage or shed? That's what we thought. They're everywhere, and if you don't have one, they are cheap to purchase. And what about those of you who have one under the hood of your musclecar? While highly modified hot rods are more in vogue now than they were in the late '80s and early '90s, originality still matters to some people and could mean better resale in the future.
Such was the case with the owner of the '65 Dodge Coronet 500 you see here. It's an original 383/330-horse car backed by a 727 TorqueFlite. It came with a 3.23 Sure Grip from the factory, but the 831/44 was rebuilt a couple of years back with a set of 3.91 cogs. The factory 383 was pulled back in 1993 and replaced with an RHS-built 383 with a mild cam and slightly massaged heads. At the time the replacement B-motor was assembled, low-compression was in vogue, and this one checked in at a regular-fuel friendly 8.0:1. Over the years, the 516 heads (with 2.08/1.74 valves) were replaced with a set of 906 heads ported by co-author Dan Foley. With an Edelbrock Performer RPM intake, 800-cfm carburetor, and ported Magnum exhaust manifolds, the 3,900-plus-pound Coronet ran a best of 13.03 at 102.9 mph. The car made regular (non-trailered) trips to dragstrips from New Jersey to Pennsylvania and Ohio, where it was consistent in the bracket classes-close to two tons of fun for its owner. But the fact of the matter was, the RHS 383-trooper that it was-was in desperate need of a freshening.
Engine technology has come a long way since that big-block was assembled in the late '80s. Street compression ratios of 10.0:1 and higher are back in style; cam technology has come a long way; and the Mopar fanatic has his choice of high-flow aluminum cylinder heads. With this in mind, the owner decided to assemble a fresh 383-based mill, one that could kick Brand X tail in the ever-more competitive world of street and strip performance. Ultimately, the owner felt if the car was born with a B-engine, it should remain with one.
Of course, just because it looks like a 383 on the outside doesn't mean it had to be one on the inside. Muscle Motors (MM) of Lansing, Michigan, is well-known in the business for its stroker kits, and we chose their 431 kit for our project (MM also offers a 496 kit for the 383). The balanced rotating kit includes Ross forged pistons, Childs & Albert rings, I-beam connecting rods, Clevite 77 bearings, and a 4340 chromoly steel crankshaft with a 3.75-inch stroke, which is a stock stroke on a 440. This crankshaft has 383 size mains, so there's no need to cut an old 440 crankshaft's mains to size or to bore and hone the main caps to the 440 size. The resulting strong-arm tactics should help this motor produce tons of torque for this heavy B-car. Muscle Motors has built a great reputation with its quality stroker kits, and we saw first-hand why. This was all top-shelf hardware.
For a cam, we selected a Crane Cams HR-230 grind, featuring .528/.539-inch lift and 230/236-degrees duration at .050 inch, with a lobe separation angle (LSA) of 112 degrees. We chose this hydraulic roller stick with its similar duration profile (that was in the 383) for a decent idle and street manners. Being a roller, it'll optimize the torque and power output from the added cubes and better breathing heads. Crane also supplied us with their high-quality roller rockers with a 1.5 ratio. We could have used Crane's 1.6 rockers to bring the total valve lift to roughly .560/.570, but we stuck with the 1.5s to ensure long valvetrain life.
When choosing cylinder heads, we went with Edelbrock aluminum castings (PN 60929). But we didn't leave them stock. Foley did his usual porting job, which was then flow benched by Wayne Williams at Cylinder Head Service in Seaville, New Jersey (presently closed for business). The Edelbrock Performer heads are fine pieces in stock trim and come with 2.14-inch intake valves and 1.81-inch on the exhaust, but we were able to improve their flow dramatically. Stock, the intake ports flowed 284 cfm at .600-inch lift, and the exhaust flowed 213 cfm. After porting, the intake side showed 301 cfm, and the exhaust handled 227 cfm at .600 lift. Equally important (and often overlooked), after back-cutting the intake valves, the low lift numbers (.200-, .300-, and .400-inch lift) increased by 8, 10, and 4 cfm, respectively (see flow charts).
We've had great success in the past strip-testing with Edelbrock's Performer RPM intake, and we decided to use one in this application. We worked some magic on this piece as well. Concentrating on the plenum area, runner entrances and exits, along with polishing the inside short turns on the numbers 5 and 7 ports, would add velocity to the mix. For a carburetor, we're going with the proven Holley 950HP to match our expected power potential.
To keep our stroker properly lubricated, we chose a new MP pump and larger capacity oil pan (7 quart) with a windage tray from Milodon. We'll break it in with conventional motor oil before switching over to full synthetic oil. We decided to try Quaker State Q Racing oil once we get it to the track.
When it comes to the parts that put it together, we look to Summit for those necessities. Summit supplied us with the ARP fasteners (main studs, head bolts, and engine accessory kit), Mopar Performance goodies (aluminum W/P housing, chrome timing cover, HV oil pump, oil filters, engine small parts kit, and crankshaft bolt), FelPro gaskets, and a Powermaster mini-starter. We felt Summit's no-name chrome valve covers would be a nice touch for the new motor. The internally balanced engine assembly (by Muscle Motors) would need a new high-quality harmonic balancer. We choose to use a proven damper-a Summit brand SFI-approved unit. These are just some of those gotta-have parts you need to assemble an engine.
Next, we dragged our 383 block out of the basement and to a local machine shop. (Danny and Jose's shop is so busy they asked us not to give them an editorial mention). These guys squeezed us in and finished all the machine work (bore and hone cylinders, square deck block, line bore, size check all parts and block) and assembled our short-block. A few words-to-the-wise: If your machine shop can't get your stuff done in a timely fashion, get it out of there.
With our finished short-block at home, it was time for final assembly. The Crane stick and timing set were installed straight up. With the cam button and timing cover in place, we moved on to the oiling system. The engine was rotated upright, and the Edelbrock heads, Crane juice roller lifters, pushrods, and roller rocker assembly finished it up. We filled it with 7 quarts and primed the long-block assembly to ensure the lube was making it to all the vital parts. Satisfied with good oil pressure and no leaks, we moved on to the valley pan and RPM intake. Once all the accessories were bolted on, we moved to droppin' it in.
We notched the K-member for pan clearance and cleaned up the engine compartment. With the new motor sitting in place, we performed all the hookups and got it running by 10 p.m. After letting it run for 25-minutes (at 1,500 to 2,000 rpm), we changed the oil (20-50W) and filter, and called it a night. The next day, we took the Dodge on a 10-mile break-in ride (total timing was set at only 30 degrees). the next day, we nailed it a couple times (miles apart) for a few seconds to feel the new power-it felt strong! With only 20 miles on the oil, we changed it again. This readied the stroker for the 80-mile ride to dyno test.
At Crazy Horse Racing in South Amboy, New Jersey, the Coronet was strapped down. Our baseline with the old 383 was 281 rwhp at 5,600 and 332 rwtq at 3,600 rpm. On the first pull with the 431 (32-degrees timing), the dyno read 381 rwhp at 6,000 and 426 rwtq at 3,800 rpms. Wow! It felt much stronger and proved it with 100 more rwhp. A backup pass on the rollers showed the same power but more torque (436). This is due to how fast you step into it considering converter lockup (flash, torque multiplication). If you step into the throttle too fast, the transmission downshifts. Next, we brought the timing up to 36 degrees. This showed us a gain of 2 hp and a lot of torque (29 lb-ft). We made a pass without the K&N Xtreme air cleaner and lost 5 hp. The timing was advanced to 39 degrees, and we didn't see any gains. On our best pulls, with timing set at 36 degrees, showed the A/F (air/fuel mixture ratio) was dead on at 13.0. That meant this well-matched motor combo with the Holley 950HP made a very efficient package.
Before the '65's one-hour ride home, the timing was set at 33 degrees. We didn't want any chance of detonation happening to the fresh motor. On the owner's ride home, he called to say he'd wasted a new Roush 427R supercharged Mustang (which is rated at 435 hp). Considering that the $51,000 Roush is an established mid- to low-12-second piece, does this mean the 431 might go into the 11s?
Track AttackWe scheduled our strip test for early November. We brought along tools, tuning supplies, 28x9 slicks, and QA1 adjustable shocks for hook. Once at Raceway Park in Englishtown, New Jersey, we were greeted by gorgeous fall weather conditions, which are conducive to low e.t.'s. The slicks were mounted, and the ignition timing was brought back to 36 degrees for max power. Before testing began, we removed the junk from the trunk and drove the Coronet onto the scales to observe 3,770 pounds. The Dodge lost 60-plus pounds off its nose thanks to the aluminum engine components and steel headers instead of cast-iron manifolds. On our first pass, the scoreboard lit up a much-improved 1.67 60-foot time. When the '65 flew through the traps, the lights read an amazing 11.78 at 114.32 mph. On a two-minute later hot-lap pass, the Dodge ran an 11.77 at 114.35 mph.
During launches, we noticed the slicks would unload and slip at about 10-15 feet out of the hole. Having tested (strip and skidpad) the QA1s before, we knew we could lower e.t.'s even further. The antiquated load-leveler shocks (rear) were installed in the late '80s. In the front were 5-year-old KYBs. Now, we would remove and replace them with the QA1s. The rear QA1s are a 12-way adjustable 50/50 (compression/extension) shock. The stiffness can be easily adjusted by turning the knob on the shock. On the front, the QA1s are 90/10s when setting the knob at zero clicks. The fronts change the valve ratio on each click and become regular 50/50 shocks when set on the max 12-clicks setting.
After setting the front QA1s on zero and the rears on 6 clicks, we pulled the Bad B to the line. During the holeshot, we watched how the rear tires stayed planted to the pavement with no spin. Looking at the clocks, we noticed an improved 1.64 60-foot with an 11.73 at 114.39 mph. Our routine backup pass showed us a consistent 1.64 60-foot and 11.74 e.t. The Coronet was hooking to the track like glue! We pulled a spark plug to check our tune. The plug looked clean (very light tan). Now with a great hook, we knew a set of bigger carburetor squirters would lower the 60-foots a bit more. TorqueFlite-equipped cars with a loose converter (2,800-plus stall) usually respond to this trick. And respond it did with the 60-foot and 1320 times dropping to a 1.62 and 11.72. We gave the Coronet a solid half-hour cool down, hoping its last pass would be its best. The cool down worked out to our liking. The 431 Dodge was really diggin', and posted a best 1.61 60-foot and 11.71 at 114.52 mph.
There are mountains of extra torque; the throttle response is instantaneous; and driveability is as good as before-better, actually, because gone are the exhaust leaks from the antique Magnum exhaust manifolds. Now the owner's got a legitimate 11-second driver musclecar-that's a claim that not even some Street Hemi guys can make.
AIRFLOW RESULTS for Edelbrock RPM Heads SUPERFLOW {{{600}}} FLOWBENCH INTAKE EXHAUST Lift Stock Ported Backcut Stock Ported .{{{100}}} 67 69 73 58 56 .{{{200}}} 136 137 145 114 117 .{{{300}}} 196 202 212 147 154 .400 243 251 255 182 192 .500 269 278 284 202 212 .600 280 299 301 213 227 .700 282 305 305 222 238Dyno ResultsTested at Crazy Horse RacingBaseline 383Peak rwhp: 281.0 at 5,600 rpmsPeak rwtq: 331.9 at 3,600 rpms
Muscle Motors 431Peak rwhp: 382.9 at 6,000 rpmsPeak rwtq: 465.1 at 3,800 rpmsPeak gains: 101.9 rwhp and 133.2 rwtqNote: At 6,300 rpm, the 431 was making 140 more rwhp than before. That's the TorqueFlite's shift point.
Strip Test ResultsBaseline 383Temp: 58 degrees; humidity: 51 pecent; barometer: 30.12Car and driver pounds: 3,885
Run/Temp Mods 60-ft eighth-mile mph quarter-mile mph 1/55 26-inch slicks, 38-timing 1.85 8.48/{{{80}}}.15 13.44/98.61 2/55 same, 11/42-hour later 1.86 8.50/80.03 13.45/98.47 3/56 45-timing 1.80 8.36/81.24 13.23/{{{100}}}.12Muscle Motors 431Temp: 51 degrees; humidity: 39 percent; barometer: 30.18Car and driver pounds: 3,780
Run/Temp Mods 60-FT Eighth-mile mph quarter-mile mph 1/49 28-inch slicks, old shocks 1.67 7.48/91.24 11.78/114.32 2/49 hot lap, slight spin 1.67 7.49/91.39 11.77/114.35 3/50 QA1s, no-spin 1.64 7.43/91.42 11.73/114.39 4/50 hot lap 1.64 7.43/91.45 11.74/114.16 5/51 #37 squirters 1.{{{62}}} 7.42/91.52 11.72/114.47 6/51 11/42-hour cool down 1.61 7.41/91.60 11.71/114.52Note: 28-inch slicks were mounted on 15x7 Centerline rims, reducing weight 40 pounds; 26-inch slicks were on 15x7 cop rims.
