Mopar 493 Engine Block Camshaft Upgrade - Bump Stick Boogie
Mopar 493 Engine Block Camshaft Upgrade
From the January, 2009 issue of Mopar Muscle
By R/T Dan Foley
Photography by R/T Dan Foley
Choosing the right camshaft to match your engine combination can be confusing. It's also very important to use the proper valvetrain components that will work reliably with your camshaft of choice. Paying careful attention to the workings of the entire valvetrain is of the utmost importance. Don't wonder if everything will be OK (we did that about our spring pressure and oiling, and then paid the price-more on that later). Never hesitate to consult with a knowledgeable tech person from one of the cam company tech lines like those at Comp Cams. They want to help you pick the right cam and components for your combination.
After a four-year run, it...
After a four-year run, it was time our Ray Barton-built 493 got some attention. The Barton team refreshed (ring, bearings, light hone) the short-block. Our engine configuration would be the same except for the implementation of a new camshaft. We decided to try one of Lunati's new VooDoo solid street roller cams. Also, we were interested to see how Lunati's latest stick would compete against the older street roller.
Back in 2003 we installed a solid-lift street roller camshaft for our 493ci RB engine in "Long Armed Wedge," from the June and July '03 issues. The roller camshaft had .575-inch lift and 262 degrees of duration at .050-inch on a 110-degree LSA. It helped our Ray Barton Wedge develop 660 lb/ft of torque at 4,100 rpm, and 621 hp at 5,600 rpm at the flywheel. That bumpstick proved to be the ideal choice for our street-driven combination, providing years of trouble-free service.
Eventually, we removed the 493 for a thorough inspection and refreshing. While planning our rebuild, we decided the 493 needed a cam with slightly less duration (7 degrees), to lower the powerband 200-300 rpm. We figured that would be just enough to match our eventual gear swap from 3.73s to 3.55s. We chose a Lunati VooDoo Solid roller stick with .600/.600-inch lift, and 255/263 degrees of duration at .050-inch, and we opted to keep a 110-degree LSA.
Once our refreshed engine with a new cam was broken in, we called our friends at SLP Performance Parts in nearby Toms River, New Jersey, for a dyno appointment. In their SuperFlow SF 840 dyno was the data saved from the original test when we used the first roller stick. Once at SLP, our buddies Ken Estelle (fabrication specialist) and Will Seppelt (project engineer) strapped the Coronet to the dyno. The engine and drivetrain combo would be the same except for the new VooDoo stick. The A/F (air/fuel mixture ratio) proved to be on the money while driving on the dyno at cruise (14.5 A/F) and WOT (12.8 A/F). The timing was set at 39 degrees total-same as it was when we tested the first camshaft.
Lunati's VooDoo cams offer...
Lunati's VooDoo cams offer aggressive ramp profiles. Their roller lifters (PN 72421LUN) are ultra high quality for maximum durability. The high-pressure springs (PN 74650LUN) utilize 590 pounds of open pressure. We specified lightweight titanium retainers (PN 76185LUN) to enable us a few hundred more rpm before valve float could possibly occur.
When Hank Daniecki, director of engineering, put the hammer down, the R/T's redline tires spun the rollers to a tune of 501 rwhp. We tried setting the timing at 32 and 36 degrees, and found our best pull of 503 rwhp using 36 degrees timing. Though we were down 20 rwhp with the new camshaft at the same 5,500-rpm peak as with the first camshaft, we were making 25 more hp at 5,100-5,200 rpm with the second one. Peak power may have been down at a higher rpm, but making more power at a lower rpm saves wear and tear on the engine. In this situation we should have used an engine dyno to show which cam made the best average power from 3,000 to 6,000 rpm. That would have determined the better bumpstick overall.
Most of us are on a mission seeking more power. So, next we plugged in Performance Distributors' new Mini-VIP 18-volt step-up regulator into our DUI distributor. On this dyno blast, we witnessed another 6 rwh-up to 509. The A/F went from 12.8 to 13.0. This was due to the better combustion from the stronger spark the Mini VIP provides. We had the possibility to pick up a few more horsepower by jetting up, but we were running out of dyno time.
While breaking-in the stroker wedge after the freshening, we test-drove the car using two of Holley's HP carbs-the 950 and the 1,000-cfm units. The smaller carb delivered better all-around drivability, but the bigger carb felt stronger above 5,000 rpm. To see the difference, we needed dyno numbers. We removed the 1,000 HP and bolted on the 950 HP and noticed a 5hp drop in power. The A/F proved to be perfect for both of the Holley carburetors.
The Lunati springs have 590...
The Lunati springs have 590 pounds of open pressure. The previous springs were rated at 440 pounds of open pressure.
The previous solid street...
The previous solid street roller (left) proved to be an outstanding cam in performance and durability in our 493 combo. The first cam in our test features .575-inch lift and 262 degrees of duration at .050-inch, and a 110 LSA (lobe separation angle). The Lunati VooDoo stick (right, PN 60334) will have to prove itself against one-bad-bumpstick. The VooDoo has more lift (.600-inch), less intake duration (255 at .050-inch), but similar exhaust duration (263 at .050-inch) and a similar LSA of 110 degrees. We thought these two competitors had the makings for a good bumpstick battle.
Street roller cams have tighter...
Street roller cams have tighter lash settings to ensure less valvetrain stress than a flat tappet camshaft. We're reusing the Comp Pro-Magnum rockers (without needle bearing fulcrums) and Comp's Hi-Tech 3/8-inch pushrods. The Comp pushrods and Lunati lifters both have an oil hole going through the middle of them. That's not necessary since the rockers are lubed through the block and heads and then into the rocker shafts.
When using a roller cam, you...
When using a roller cam, you must also use a bronze-type distributor/cam gear on the oil pump driveshaft. We used the Milodon (left, PN 21525) oil pump drive assembly. The Lunati (center, PN 88426) bronze gear could have been pressed on and pinned to the original shaft by a local machine shop. The gear (right) has over 8,000 miles on it. Inspect the bronze gear for wear every few thousand miles.
We were curious to see how quick the R/T would quarter-mile with its fresh stroker combo. We mounted the Hoosier 30x9x15-inch slicks and 26-inch front skinnies before pulling up to the line. At this point the 950 HP and the 3.73s were still part of the R/T's equipment. Out of the hole, the slicks spun and we received a 1.60 60-foot time, but we still ran an impressive 10.70 at 126.40. We pulled around again and heated the Hoosiers again. This pass produced a no-spin 60-foot of 1.50, enabling the big B-Body to boogie to a quicker 10.56 at 126.10 mph! We can't tell you how happy we are to have a 10-second, pump gas, real street car.
Roller cams offer better lobe profiles than flat tappet sticks, thus better performance. We honestly can't say which bumpstick won our test. Using a chassis dyno with a loose converter was not conducive testing. We've heard of racers going quicker using a motor that showed less hp on the dyno. It's always in the combination. If it's in your budget, a roller cam matched to your combo is the biggest winner.
Note: Please read the captions to see the trials and tribulations we encountered to perform this cam test. We hope this prevents others from experiencing valvetrain component problems. Pay close attention and don't be afraid to ask questions on the cam tech line about your intended cam and valvetrain parts combo for your engine.
|Chassis Dyno Results|
Tested at SLP Performance Parts
SuperFlow SF840 Dyno
|Ray Barton 493 with .575-Inch Lift Cam|
|Peak rwhp||524 at 5,500 rpm|
|Peak rwtq||512 at 5,300 rpm|
|Ray Barton 493 with Voodoo .600-Inch Lift Cam|
|Peak rwhp||503 at 5,500 rpm|
|Peak rwtq||494 at 5,300 rpm|
|R/T Quick Specs|
|Short-block||'70 440, Eagle crank 4340-steel forging 4.15 stroke, JE flat-top pistons, Manley/Barton H-beam rods |
|Camshaft||Lunati VooDoo roller, 255/263 duration at .050-inch lift, .600-inch lift|
|Valvetrain||Comp roller lifters, Hi-Tech 3/8-inch pushrods, Pro Magnum roller rockers, dual valvesprings, Titanium retainers|
|Heads||Edelbrock Performer RPM, 2.14/1.81 valves, ported, flow 293/227 cfm at .600-inch lift.|
|Induction||MP M1 single plane, polished plenum, dividers, runners, except floor left as-cast, no gasket matching. Wilson Manifolds 1-inch, 4-hole tapered spacer (PN 004110). Holley 950HP, 78 jets, 40 squirters.|
|Exhaust||2-inch tti headers, 3-inch tti exhaust with DynoMax Ultra Flo mufflers.|
|Drivetrain||Pro-Formance-built 727 with rollerized planetary, Hemi governor for auto upshifts at 6,200 rpm, Dynamic 9.5-inch converter. Denny's 4-inch HD aluminum driveshaft. Randy's Ring and Pinion-built 83/4 w/3.73s and Detroit Locker, Yukon axles.|
|Suspension||FFI and Magnum Force front-end components, Stock leaf springs re-arched with 1 leaf added per side, QA1 shocks, Hoosier 30x9R-15 slicks, 26-inch skinnies, Weld Superlites 15x8 and 15x4.|
|Test Weight||3,850 lbs.|
|Best ET/MPH||10.56 at 126 mph|
With only five miles on the...
With only five miles on the engine after reassembly, we ran into a problem. The rocker on the left seized on the shaft and also damaged the pushrod. This was due to inadequate oil pressure at the rocker arm assembly and the high pressure of the springs.The proper fix was to install rocker arms with needle bearing fulcrums and pushrods (cupped end type) without the oiling hole. We could have used either lifters or pushrods without the oil hole to cure our oil pressure bleed-down problem.
There's no way we could rely...
There's no way we could rely on regular rubber motor mounts for our wild Wedge. Schumacher's Poly-Loc mount (left) features polyurethane construction with internal locking plates (see cut-a-way) to prevent blow-out. They're holding up well!
Back together and running,...
Back together and running, we want to put on a couple hundred more miles before dyno testing. We figured this would be a good time for us to try out two different Holley HP carbs. The 1,000 HP (PN 0-80513-1) exhibits larger venturis compared to the 950HP (PN 0-80496-1). Driving around (mixed city and highway) the 950HP was the hands down winner. At WOT between 5,000-6,000 rpms (top-end charge) was when the 1,000HP shined.
On SLP's dyno, we were surprised...
On SLP's dyno, we were surprised to learn we were down 20 hp at the same peak (5,500 rpms) as the first cam. When the 91/2-inch Dynamic converter locked up at 5,000-5,200 rpms, the VooDoo cam was averaging 25 more horsepower. At 5,800 to 6,100 rpm, the VooDoo cam was making the same power. The older-tech roller cam held its own against the new-tech VooDoo roller. Only if we had tested the previous camshaft for average horsepower on an engine dyno (most average power 3,000 to 6,000rpm), we could have declared a winner in this cam contest.
Mounted on the firewall (where...
Mounted on the firewall (where the ballast resistor once was) is the Performance Distributors Mini VIP 18-volt step-up regulator. It works with most 12-volt electronic ignition systems that can withstand 18 volts. We plugged the Mini VIP into our DUI distributor and realized six more horsepower to the wheels. That would easily be worth a tenth at the track.
While on the dyno, we removed...
While on the dyno, we removed the 1,000HP carburetor and replaced it with the 950HP. We lost five horsepower, but it offered better drivability. With that, the 950 Holley still resides on top of our motor.