Of all the big-blocks built by the Chrysler Corporation, the 383 is the most widely produced, and likely the most underrated of them all. As a big-block, the 383’s displacement isn’t nearly as small as the 350 or 361 cubic-inch B-series engines produced by Chrysler in the early days of the big-block, but it’s also not nearly as large as the popular 440 engine either. When the Chrysler Corporation decided to add the 906 cylinder heads and high-performance 440 camshaft to the 383 for the 1968 model year, the engine immediately became a hit among enthusiasts of the era. Installed in the Plymouth Road Runner and Dodge Superbee, this engine easily propelled these B-Bodies to low 14 second quarter-mile times at trap speeds of more than 100 mph. And with a little work, the 383 could go deep into the 13s and still be much more drivable than the optional Hemi.

With a 4.250-inch bore size, a size coincidentally shared with the famous 426 Hemi, and a 3.380-inch stroke, the 383 is somewhat of a small- to mid-size big-block, and takes advantage of the best attributes of both big- and small-block V-8s. With a short stroke, the 383 revs quickly and is capable of high rpm, just like a 340 small-block. But with a large bore and cubic inches on its side, the 383 also provides the abundant torque big-blocks are known for. For these reasons, and because 383s are available and inexpensive to build, this engine is one of our favorites here at Mopar Muscle.

We’ve run 383 big-blocks in both race cars and street cars, and have had success with the engine in each application. It is on the street, however, that we feel the 383 really shines. Big enough to provide ample torque and horsepower to make even a large car fun to drive, the 383 is also small enough that it gets decent mileage as well. In fact, the 383 burns far less fuel than a 440, and even outperforms many 360 small-blocks in terms of fuel economy. Add these attributes to the fact that so many 383s were built, and we feel this engine is a great choice for many street or street/strip machines. Our Chrysler Newport project vehicle came equipped with a 383 two-barrel from the factory, but when we got the car we replaced that engine with a fresher 383 that we had built some years back.

Price Tag
Comp Cams hydraulic flat-tappet cam and lifters $225.95
Comp double-roller timing set $47.95
Edelbrock Performer RPM intake manifold $245.95
Edelbrock Performer 750 carb 213.97

The 383 in our Newport features a ’67 block, and a pair of stock, unported 906 cylinder heads. This engine was built some 20 years ago (when this author was still in college), and was built with the intention of making the ’68 Road Runner four-speed car I was driving both fun and economical. Gasoline was poor quality back then, and unleaded fuel was the only type available. Even worse, the fuel suppliers hadn’t figured out the additive packages yet to make old engines run well on unleaded gasoline, so that was a consideration when building this engine. Equipped with a stock crankshaft and connecting rods, cast dish pistons, and open chamber heads, this engine has just 8.5:1 compression. The flat-tappet camshaft this 383 is equipped with is a very old and mild Direct Connection Purple Shaft, with specs very similar to the stock 440 Six-Pack camshaft.

Topped with an old-school Weiand dual-plane intake and 650-cfm Carter AVS carburetor, this engine ran well enough to get our Newport around without feeling underpowered, but we certainly felt we could improve power and torque with a couple of simple bolt-on upgrades to our 383. In an earlier article, we added tti headers and 21⁄2-inch dual exhaust. These modifications improved power and torque, but our 383 was still only making some 223 horsepower and 298 lb-ft of torque to the rear wheels. Wanting to step up the power a bit without sacrificing any drivability, we decided that a cam swap to a more modern Comp cam with similar specs would help. While we were at it, we chose an Edelbrock Performer RPM dual-plane aluminum intake and Edelbrock 750-cfm Performer series carburetor for our 383.

Camshaft technology has come a long way, especially when it comes to Mopar camshafts. Early aftermarket cams for Mopars were designed generically to fit any application, not taking advantage of the Mopar’s larger .904 diameter lifter size. Luckily, Comp Cams recognized that with the larger diameter lifter that a more aggressive ramp rate could be used, getting the valve open quicker and allowing more air and fuel into the cylinder. Utilizing this concept, a camshaft with very mild specifications can make significantly more power than a stock or early aftermarket cam with similar specs. For our 383, we chose a Comp Extreme Energy hydraulic flat-tappet camshaft with .477 intake and .480 exhaust lift, and 268 and 280 degrees of advertised duration respectively. This cam has nearly the same specs as the cam we’re replacing, with only slightly more lift and duration, but takes advantage of Comp’s modern lobe design and has a wider 110 degrees of lobe separation.

Important Numbers
RPM x1000 hp ft-lbs
2.80 154.01 288.88
3.00 173.99 304.60
3.20 188.71 309.72
3.40 203.60 314.51
3.60 213.97 312.17
3.80 223.83 309.36
4.00 231.73 304.27
4.20 240.43 300.67
4.40 244.93 292.37
4.60 244.00 278.59
4.80 240.62 263.30
4.60 -INF -INF
4.40 -156.38 -186.66

Changing the camshaft in a big-block Mopar is fairly straightforward, and can be accomplished without much trouble with the engine still in the car. We recommend replacing the timing chain any time you’re in this part of the engine, and we chose to replace our entire stock-style timing set with a Comp double roller unit. The lifters must also be changed any time the camshaft is replaced, since lifters establish wear patterns to the individual cam lobes. Failure to replace lifters or swapping lifters from lobe to lobe will certainly cause premature wear, and can round off a cam lobe quickly. We picked a set of Comp’s Pro Magnum hydraulic lifters to match our Comp cam.

It’s also a good idea to check piston-to-valve clearance any time you install a cam with more lift and duration, unless you’re quite sure you have enough room Valve retainer to valve guide clearance is also important to check, and make sure the valvesprings are compatible with the new camshaft. Having previously checked the vital clearances in our engine, we knew this camshaft would work just fine. Additionally, the open and seat pressures of our valvesprings were right in line with the specs called for by Comp, so we didn’t deem it necessary to change valvesprings. If you’re not sure about your engine, however, it is always a good idea to double check all of the critical dimensions and match the valvesprings to the camshaft being used.

Replacing the cam while the engine was in our C-Body required removing the radiator and air-conditioning condenser, but otherwise no special tools or techniques were required other than a puller for the harmonic balancer. All told we had our cam swap completed in a day’s work, and ready for dyno testing on our Dynojet chassis dyno. We decided to test our car after the cam swap, and then install an Edelbrock intake and carburetor to see how those parts would also help our combination. Remember that simply swapping a camshaft might not benefit the engine as much as you’d expect if the engine isn’t getting the air and fuel required to make it perform properly.

On the chassis dyno, we made a first pull and picked up some 18 horsepower with the cam swap alone. Torque was up as well, but not as much as we predicted. So we bolted on our Edelbrock Performer RPM dual-plane intake manifold and 750-cfm Edelbrock Performer Carb. The addition of these parts really enhanced our camshaft swap, and power was up by 22 horsepower at peak, to 245.44 from 223.91, with great gains across the board. Torque was up as well by more than 17 lb-ft at peak with across the board gains throughout the rpm range.

Results
Baseline | cam only | cam/intake/carb
Horsepower 223.91 241.41 245.44
Torque 298.55 307.64 315.73

Remember that these numbers are at the rear wheels, and some 30 to 35 percent lower than what would show on an engine dyno. Also remember that this is a stock, low compression engine so we don’t expect it to be a true powerhouse. Even so, more than a 10 percent gain in horsepower for a day’s work is not too shabby. Better yet, our Newport is now even more fun to drive. Be sure to check out moparmuscle.com for all of the details of our testing, and to see video of the big Chrysler on the chassis dyno. mm

SOURCE
Edelbrock (Carbs)
800-416-8628
http://www.edelbrock.com
Comp Cams
3406 Democrat Rd
Memphis
TN  38118
800-999-0853
www.compcams.com
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