Big Torque 383 Build - Car Craft Magazine

Big Torque 383 Build Connecting Rod Pairs

During the mockup phase of the buildup, a couple of the connecting rod pairs required minor filing to achieve the proper side clearance. The minimum rod side clearance is 0.008 inch with a range up to 0.015 inch. Excessive side clearance combined with a high-volume oil pump pushes more oil up on the cylinder wall, which can cause oil-consumption problems.

During the mockup phase of the buildup, a couple of the connecting rod pairs required mino

Flow Chart
Canfield 195cc Heads
Valve Lift	Intake	Exhaust	E/I
0.100	61	51	83%
0.200	128	103	80%
0.300	191	143	75%
0.400	238	170	71%
0.500	271	189	70%
0.600	254	200	79%
E/I – Exhaust-to-intake flow relationship in percentage

Dyno Time
With our 383 safely buttoned up, we tossed it in the back of our trusty GMC pickup and headed out to Westech's dyno. Steve Brul and crew bolted our externally balanced motor up on the SuperFlow 902, and we were ready to make some noise after bolting on a set of Hedman 13/4-inch dyno headers. We'll also come clean that we left the exhaust uncorked just so the power numbers would look better. If we had added a complete 21/2-inch muffled exhaust system, the power numbers would be more conservative by perhaps 10 to 15 hp.

After installing the crank, rods, and pistons, we checked the position of the Howard's flat-tappet hydraulic camshaft. This was fortuitous because we discovered the cam was retarded by 3 degrees. The Competition Products adjustable timing set allowed us to advance the cam 4 degrees to position it 1 degree advanced.

After installing the crank, rods, and pistons, we checked the position of the Howard's fla

With the engine on the dyno, we spent some time pressure-lubing the engine by turning it every 90 degrees until we had oil into each of the 16 rocker arms. Using Shell Rotella T diesel oil for the added zinc and phosphorous to help the cam on its initial break-in, we also added a pint of Lucas Engine Break-In Additive for some extra insurance. Also, because removing the inner valvesprings to reduce the load on the lifters was not high on our to-do list, we opted to start the engine with a set of Comp Cams 1.3:1 break-in rocker arms. These rockers minimize the valve lift, which also reduces the valvespring load. Once we had about 25 minutes on the engine at between 2,500 and 2,800 rpm at a slight load, we made a pull on the engine with the 1.3:1 rockers just for grins. We were surprised that the 383 still managed to crank out a little more than 400 hp with barely 0.400 inch intake lift. Then, we swapped over to a set of the Scorpion 1.6:1 roller rockers to really get serious. Our first pull produced a surprising 461 lb-ft of torque and 439 hp from the conservative Howard's hydraulic flat-tappet cam. We followed that up with several pulls that netted almost identical power curves, which showed us that the engine was very repeatable.

Next, after a short cooling-off period, we took advantage of the Comp Cams two-piece timing chain cover to quickly remove the Howard's cam and replace it with the mechanical Camshaft Innovations grind. After we once again ran through the entire flat-tappet-cam break-in procedure, including the 1.3:1 rockers, it didn't take long for the new cam to push the power peak up to 471 hp. That's when we added a 1-inch carb spacer to the Edelbrock intake that delivered an excellent 477 hp at 6,100. What was also impressive was how the power curve around peak horsepower remained almost flat right out to 6,500 rpm. This may mean there is a minor cork somewhere that, once uncovered, could produce even more peak horsepower. Plus, the engine sounded happy right up to 6,500 rpm, which means the valvetrain was completely stable with no valve-float issues despite the 1.7:1 rocker ratio. The new Cam Innovations grind also broadened the powerband to a respectable 1,600 rpm between peak torque at 4,500 and peak horsepower at 6,100 rpm. If we include the power at 6,500 rpm, the powerband swells to 2,000 rpm! The mark of a strong street engine is one with the widest spread between peak torque and peak horsepower. This increases the engine's overall average power and drastically improves its acceleration potential.

We used the Comp Cams two-piece timing chain cover to expedite the swap to the Camshaft Innovations grind.
We used the Comp Cams two-piece timing chain cover to expedite the swap to the Camshaft In
With the engine up on the Westech dyno, we initiated the new Howard's cam with a witch's brew of Rotella T 15W-40 engine oil and Lucas Break-In Lube. We also used a set of Comp break-in rocker arms with a 1.3:1 ratio making it easier on the cam and lifters for the initial run-in. We then changed to a set of 1.6:1 Scorpion rockers for the test.
With the engine up on the Westech dyno, we initiated the new Howard's cam with a witch's b
It didn't take much thought to choose an Edelbrock Performer RPM Air-Gap intake for this test, since it's tough to beat this dual-plane's overall power potential. We also added an MSD distributor and a Holley Street HP carburetor to hedge our horsepower bet.
It didn't take much thought to choose an Edelbrock Performer RPM Air-Gap intake for this t