Mike Barton degreed-in the...
Mike Barton degreed-in the roller cam for us. A camshaft can't perform properly unless it's been degreed according to the cam card. Naturally, we could have advanced or retarded the cam to move the power curve around, but we didn't in order to have a fair comparison. The same RBRE 3-bolt steel billet timing set was used for both cams. Mike also observed the gross lift to check the cam lift and rocker geometry, which were right on.
Rolling With It
At the beginning of this buildup, your hardheaded author wanted a particular solid street-roller cam for this motor. Ray suggested we try one of his solid flat-tappet cams that would make the power we wanted for less money than a roller cam. The RBRE .638-lift cam proved its worth, making more power than we anticipated. "Hey Ray, can we still try that roller?" we asked. Ray responded, "Why not?" Remember, upgrading to a roller cam will add $700 to $900 to the price of the motor.
Our cam choice was the Comp Cams Magnum solid street roller with .575-inch lift and .262-degree duration at .050, and a 110-lobe separation. The Comp street-roller cams have gradual and gentle ramps that are easy on the valvetrain. The next day, we easily performed the cam swap. The same RBRE three-bolt billet timing set and Comp Cams 929 double valvesprings were used. The taller Comp roller lifters necessitated the use of pushrods that were .200 inch shorter. Roller cams also require the use of a cam button to prevent cam walk. Also, a bronze gear was needed on the intermediate shaft. After Mike Barton degreed the cam and I lashed the valves, we readied the stroker for its next dyno session.
For a fair comparison, the same configuration of 1 7⁄8-inch headers, carb spacer, and carb, was used. The powerplant was warmed up for 25 minutes, and then the valve lash was reset. After a few preliminary pulls, the wedge was making its most power again at 39-degrees timing. On the best baseline blast, we observed 608 hp at 5,500 rpm (down 23 hp) and 660 lb-ft of torque at 4,100 rpm (up 21 lb-ft). The 3,500-6,000-rpm average horsepower was down by only 1 hp, but torque was up by 3 lb-ft. This is an acceptable trade-off in power for our heavy street driver. We'll call this "flat tappet versus roller cam fight an even brawl."
Once the flat-tappet cam was...
Once the flat-tappet cam was broken in, the inner springs were put back in their places-inside the outer spring. Valve lash was reset on both cams after initial cam break-in and warm-up (25 minutes). Going to the roller, we lost 23 peak horsepower, but gained 21 lb-ft of torque. Peak horsepower came in at 400 rpm less, and peak torque came in at 600 rpm less-good for street drivability in our 4,000-plus-pound B-Body.
A little disappointed because the roller had less peak horsepower, we decided to see if a few tuning changes could get it back. First, we took a shot at leaning out the jetting. The 1000 Demon's stock 85/93 jets were replaced with a set of 83/91s. The jet swap picked up the peak ponies by 5 hp. Peak power was now up to 613 hp at 5,500 rpm. Average power was up a tad at 2 hp and 2 lb-ft of torque. Could we get peak power back to 631 hp with only an hour left in the day?
More Tuned Tubes
Most header manufacturers say the 1 7⁄8-inch header is sufficient for up to 575 hp. Hovering over 600 hp, we ordered a set of 2-inch tti's with 3 1⁄2-inch collectors. Would the 2-inch be too big like the 2 1⁄4-inch dyno tubes used at the beginning of dyno testing? We put the hammer down and soon realized 8 more peak horsepower. This moved peak horsepower up 200 rpm higher, topping out at 621 hp at 5,700 rpm. A plug check revealed the fuel mixture was right on. More tuning would be on the agenda after we dropped our Barton Bruiser in the R/T.
Engine replacement was simple enough. We just pulled out the old 440, dropped in the new 493, bolted it in, and went! We did change the oil, and after 300 miles, we'll switch over to Mobil 1 15w50 synthetic. RBRE built us a powerhouse that has the same 1,200-rpm idle quality as the old 440. Yet, this monster has better street drivability, pulling faster through the gears, and it has more top-end power. How does smoking 'em at a 50-mph roll sound? We were anxious to drive to E-Town to strip-test our new Barton Brute, but it was January and what were we to do?
A plug inspection revealed...
A plug inspection revealed we could lean the carb from the stock 85/93 jetting. We tried a set of 83/91 jets and scored 5 more horsepower at peak rpm. Most large cfm carbs are calibrated on the rich side for the typical Chevy big-block, which has larger, less efficient parts. We wanted to lean it out a little more, but we would have to wait and see how the bigger pipes worked on our combo.
The 1 7⁄8-inch tti tubes...
The 1 7⁄8-inch tti tubes on top, which have been in the R/T for over three years, had a greater torque advantage over the 2 1⁄4-inch dyno headers. Below, the new 2-inch tti's were worth 8 hp over the 1 7⁄8-inch tubes. Notice the bigger 3 1⁄2-inch collector on the 2-inch, compared to the 3-inch collector on the 1 7⁄8-inch. The higher-horsepower 2-inch tti's will reside in the R/T and bolt up to the 7-year-old 3-inch exhaust.
Switching over from the old...
Switching over from the old 440 to the Barton street beast was simple. We used the Eagle six-bolt crank just so we could reuse the old 440's HD flexplate. The bottom belt pulley bolted right up to the indexed ATI Super Damper. The aluminum Edelbrock heads and MP aluminum water-pump housing will reduce front-end weight by 55 pounds. The spark plugs were removed, and the headers were tied aside, making it easy to drop the RB into place.
Performance Distributors products...
Performance Distributors products have proven themselves in delivering smoother power, torque, and efficiency.