A couple of weeks ago, we brought you Part 1 of our original 1971 Plymouth Road Runner’s 383 B-block. As many on our Facebook page noted that “there ain’t anything performance about good old 1100 gram cast Mopar pistons,” we’re looking to adequately recreate the factory-specs (and dyno performance) of this post smog-era 383.
We start with the completed short block in the upright position. It is a good idea to chase each head bolt hole in the block with a tap to make sure each bolt will install correctly. Next, spray clean all areas to remove any dirt or shavings and re-wipe all the pistons and head surfaces with a clean freshly-oiled rag. Place the head gaskets on the block. It is not recommended to use any sealer on these gaskets. Spray clean the heads and wipe dry before installation. Then position each head onto the block.
There isn’t a left or right head, as they are the same. Again, chase the threads where the intake bolts will go. If using stock, original head bolts, dip the threads in oil and insert them in the head. If you’re using ARP bolts, apply the provided assembly moly lube to the threads and washers and install. Just snug all bolts in place on both sides of the engine. Refer to the factory shop manual for the tightening sequence of the head bolts and torque according to specs. ARP bolts use different torque specs than the stock bolts.
Above left: Pre-lube with assembly lube all of the lifters making sure they have been cleaned even if they are fresh out of the box and install in the lifter bores. Make sure they move freely in the bore. Install the head gasket. This set does not recommend using any sealer. Above right: Take the already completely rebuilt and clean head over to the block. The stock heads are identical so there isn’t a left or right.
Above left: There are positioning pins in the block so once the head is in place it will not fall off. Above right: Lube the ends of the push rods and insert into the lifters. Put some assembly lube on the ends of all the valves where they will contact the original rocker arms.
Spray clean your new lifters and liberally coat each one with assembly lube, then slide them in the bores. If using new push rods or even the originals, clean and lube each end and install them in the lifter through the head. Lube each valve contact point.
Stock rocker assemblies are very basic and yet very reliable for street use. There is a left and a right individual rocker but no left and right assemblies. The rocker shaft must have the oil holes facing toward the block. The spacer and attaching bolts and brackets all go a certain way. Clean each component and reassemble with oil on all parts.
Take each assembly and position them on the head perches. It helps to have two pairs of hands to keep all the push rods and rockers in line. Slowly tighten and make sure you are not putting a bind on a push rod that is not in the lifter and rocker recess. Repeat for both sides and once the shaft is seated torques to specs.
Above left: If you are using the original bolts make sure they are clean and dip them in engine oil. If you are using new ARP bolts like we are use the lube provided. Note if you are going to show the car in an Original Equipment setting use only original style head bolts. Since they are hard to see and the new bolts will not have a chance to fail on this build ARP bolts were used. Follow the tightening reference for the head bolts found in your Factory Service manual and torque all head bolts to specifications. Above center: There is a left and a right rocker, several spacers, different size bolts with specific spacers and the rocker shaft has oiling holes. If you have any doubt as to how your rocker assembly goes you can use this picture as a reference. Above right: Torque the rocker assembly bolts to specifications and repeat on the other side.
Above left: Position the rocker assembly with all bolts in place and take it to the block. Above center: Carefully line up each rocker, push rod, and bolt with spacer as you set the assembly on the head. Above right: It is good to have an extra pair of hands to hold the rockers and push rods in position.
We recommend using the valley pan gasket that has the heat cross over blocked. Unless you live in an area with very cold climate or you plan to drive the car daily, you do not need the heat cross over to be functional. Also if you do not block it off, your intake will discolor and blister after a few hours of operation of the engine. Only use the metal gasket, no need to use the additional felt gaskets that some kits include. Have the rails and bolts cleaned and ready to install. Put a dab of RTV sealer in each corner and lay the gasket in place. Install the intake manifold and torques to specs.
On all wedge big blocks, the negative battery cable is mounted underneath the return carburetor spring bracket. The cable was attached when the engine was painted. Many restoration articles have said only a small portion of the cable was painted. If you are lucky enough to have your original cable you will need to duplicate how much paint was actually on your cable. For most that will not be the case. This engine actually has the original cable to use as a guide and it was almost entirely painted all the way up to the end.
As you are installing your intake, be sure and mount the cable then torque it down. On engines before 1970, there was also a negative ground wire on the passenger rear side of the engine that was also attached and painted. The harmonic balancer, water pump, water pump housing, inlet tubes, throttle bracket, any spark plug wire brackets, valve covers with the PCV rubber grommet and valve mounted on the cover, and exhaust manifolds were also attached at the factory when the engine was painted. Yes, we said exhaust, and it burned off as soon as the car was driven.
Above left: These are the original valley pan bolts and bars. There were even indentions showing where the two smaller bolts were. I am not saying all engines are like this but this one was so I put it back the way I found it. Above center: Before putting the valley pan gasket on the only sealer needed is a squeeze of silicone in all four corners where the heads meet the block. No other sealer is needed on the mating surfaces of the valley pan gasket. Above right: No other sealer is needed on the mating surfaces of the valley pan gasket.
Above left: The new metal gasket needs to pressed down so it will bend and conform to the block and heads. Above right: Again an extra set of hands helps to hold the gasket in place while the intake is placed on the engine.
Each owner has to decide whether he will paint his exhaust or not. This owner chose not to paint since he did not want the burned-paint look on his car. Most people do choose not to paint them but to be completely factory correct they were painted. Use cork gaskets on the valve covers because they show. Attach all of the additional parts to your long block. Then mask off all open holes and wipe the entire engine down with lacquer thinner.
There are two ways to paint an engine. You can use a paint gun or you can use a spray can. There are also several brands and colors that are supposed to be the correct factory color. If your car is a 1966–1968 big block it was painted Chrysler Blue. Many people refer to it as turquoise.
Also if your car has air conditioning it was painted Chrysler Blue. All non-air cars in 1969-70 were painted Street Hemi Orange. Chrysler even produces spray cans of these paints, but they are not close to the original color.
Above far left: The original intake bolts did not have any washers on the cast iron intakes. On an aluminum Dodge 69 ½ Six-Pack or the Plymouth 69 ½ 6-Barrel intake there were flat washers originally used. Above center left: Snug down the intake bolts starting with the inner bolts, alternating from side to side, working toward the last outside bolts. Above center right: On the front drivers side intake bolt, the throttle-return bracket was mounted. They varied in style from year to year. The one in the picture is a 71 type with the serrations in the bracket. The 3×2 cars also had the serrations on the bracket. The negative battery cable is attached under the throttle return spring bracket. I usually come back and attach it after the intake valley pan corner silicone seal has had a chance to dry. Above far right: After everything is in place and equally tightened down, torque all the bolts to specifications using the same inward out, side to side alternating pattern.
Above left: You need to use the cork gaskets since the engine used those originally and the tabs of the valve covers do show. We use silicone sealer on both sides of the gaskets. Above right: Attach the gasket to the valve cover first and then apply a thin coat of silicone sealer to the gasket.
We highly recommend using a spray gun and acrylic enamel paint the same way they did it at the factory. You will get much more paint, a higher quality paint, and better coverage than with spray cans. If you cannot use a gun, we only recommend PlastiCoat Chrysler Orange. It has more gloss than original but most people like its final results. It is very close to the original color and holds up very well over the years.
We recommend using the paint that Frank Badalson sells for the closest color and appearance to factory original today. It can be purchased at Auto Restoration Parts Supply, along with many other factory correct reproduction parts. You can contact them at (804) 743-0570, Fax (804) 743-8275, or email at email@example.com
You will get a pint of the paint and it will cover the engine. It is reduced two parts paint, one part reducer. You do not use primer or hardener since the hardener will add gloss. You can use a touch up gun or we use a HVLP gravity feed gun.
Above left: Place the valve covers on the heads and finger tighten all the bolts. Once they are finger tight go back and tighten each bolt ¾ of a turn. Do not over tighten or the cork with split and the covers will leak. Above right: Tape off the oil filler hole and intake for paint later.
Above left: Next install the water pump housing. This picture is a great reference. The only bolt that used a washer is the one behind the heater hose nipple. Once the nipple is installed you can loosen this bolt but cannot remove it. Use this picture for reference as to what bolts were used on the water pump and water pump housing. Above right: After installing the water pump housing put sealer on the threads of the heater hose nipples. They must be tightened and not damaged so you can use this method to achieve flawless results.
Wet the floor around where you will be painting to keep down the dust, and then shoot. Short bursts and careful attention must be paid while painting to keep runs to a minimum and still cover everything that needs paint. Use a mask and it can be painted outside or inside with proper ventilation. After wiping the engine down, blow it all off with an air gun and tack cloth everything. Remove the tape on the engine as soon as it is no longer tacky but be careful you can still mess up the paint until it dries over night.
As you can see the final results are fabulous. It is also factory correct in color, sheen, and painted components. By taking your time and paying attention to details you can completely restore your engine doing most of the work yourself. We always suggest taking your engine to a dyno shop where they can break it in, tune it for maximum performance, and fix any problems before you install it back in your ride. If that is not possible be sure and run the engine at start up at 2000 rpms for 20 minutes to seat the rings and break in the cam.
Above left: We use a touch up gun to paint the engine. That way you can get to all the little nooks and crannies. Above right: The absolute best original paint match can be purchased from Frank Badalson. He sells pints of the single stage enamel. It is reduced 2 parts paint one part reducer. You will have enough paint for one good wet coat.
Above left: Wet the floor to cut down on dust. It is preferred to paint in a booth but this engine was built in the owners garage and we had a perfect day with no wind to paint. Above right: The full size gun can be used to begin painting followed with the touch up gun for the tight places.
Of course, we took our finished 383 to Mike Petralia at Hardcore Horsepower to help break in our engine and see how the low-deck big block’s power output fared against the factory’s claim of 300 horsepower. After following the steps in the Factory Service Manual for installing the distributor, firing order, spark plug wire routing, carburetor and fuel line set up, we discovered that our distributor was putting on too much advance. Even starting with zero advance, we’d rocket up to 40-plus-degrees.
Petralia swapped in a pair of MSD springs which helped slow the ignition’s advance, but still ran up to 38 degrees of total advance. With the timing “as good as it was gonna get,” we finally let the 383 wind up and run. After a handful of runs, the low compression (8.5:1) B-block huffed out a maximum 287 horsepower and a slightly-more encouraging 363 ft. lbs. of torque.
Petralia also emphasized that the 383 was heavily over-cammed, particularly with the low-compression pistons and nearly flat intake manifold. Petralia assured that the overall horsepower number would increase as the rings seated a little more over time with additional use, and promised that a pair of headers would definitely “wake it up.” Although we have no plans to modify the engine, it’s encouraging to know that there is untapped power to be had by uncorking intake and exhaust.
Above left: With our fresh 383 assembled, we readied it for dyno testing. Above center: We made sure to prime the oil system prior to firing up the engine. Above right: Final tweaks were made to the factory ignition to help curb the total advance setting.
Above left: In Hardcore Horsepower’s dyno cell, our 383 did its best to breathe through the near-flat intake manifold and restrictive cast headers. Above right: As per the dyno sheet, our 8.5:1 compression 383 made a total peak 287 horsepower and 363 ft. lbs. of torque.