The Chevrolet 1-ton dualie pickup has always been a symbol of power. With its monstrous hood and huge dualie wheel humps, the truck just grunts power like a sliver-back gorilla. Looks can be deceiving, however, and in the late '70s to mid '80s even the big-block dualies lacked enough power to back up their monster image. Most of the problem came from Big Brother's slapping emissions restrictions on the trucks, and our '82 test brute was no exception. Granted, when Editor Cole spotted this truck and shelled out a diminutive $2,500 for it, he almost got the deal of the century. But these big trucks are for hauling project cars around, and this one's big-block had just about hauled its last bail of hay.
Our dualie's big-block would breath better and grunt out tons more power with some new Ede
Plans were quickly made for a brute force upgrade centering on increasing the truck's torque output in real street rpm. So the dualie was driven into the newly open-for-business McMullen Argus Tech Center where it was first subjected to a rigorous day's lashings on the mighty Dyno-Jet chassis dynamometer.
Since the dualie's big-block was bone stock and dead tired, it didn't take long to find maximum horsepower. At the rear wheels the truck actually made some impressive torque for such an old beast. It had no trouble cranking out 324 lb-ft of torque at a very low 2,600 rpm. This meant that the 454-cid Rat under its hood was still up to the task of hauling a heavy load. Unfortunately, peak horsepower really fell short of respectable because the big-block could barely muster 190 ponies at 3,900 rpm. Keep in mind that these figures are at the rear wheels and calculate at bare minimum a 25 percent correction factor for power loss through the giant two-piece drive shaft and 14-bolt rearend. If you do the math, this 454 was actually making almost 250hp and 400 lb-ft of torque. Yet, those were hardly numbers for a big-block to be proud of, so a call was made to Edelbrock for some suggestions.
Any time you're removing tubes and wires from the engine, it's best to label them as they
Edelbrock's technicians informed us that big-blocks of this truck's vintage usually employed flat-top or even dished pistons, and our Rat could suffer from really low compression if we swapped on a pair of Edelbrock's aluminum heads with 110cc combustion chambers. Thankfully, Edelbrock has thought of a way to avoid this potential problem and offers a special 100cc "high-compression" head just for big-blocks with pistons like these. While this head will not actually squeeze much more compression out of our big-block, it will keep it around 8.5-9:1, which is just right for a towing monster on pump gas. So the decision was made to order a set of Edelbrock's High-Compression Performer heads from Jeg's High Performance Warehouse.
We figured that since we were using Edelbrock heads, we might as well include most of the Edelbrock Performer line of components also. So we added to our order a Performer 2-O intake manifold, a 795-cfm Performer Q-Jet carb, and some 2-inch primary-tube Hedman headers. Unfortunately, the Edelbrock Performer series camshaft was too big for our dualie's towing needs, so we chose a Crane PowerMax H-260-2 hydraulic cam and lifter kit. We also ordered Crane's replacement pushrods and some new Blazer aluminum roller rocker arms with a standard 1.7:1 big-block ratio. And since this power bolt-on bonanza wouldn't be complete until after a trip to the muffler shop for installation of true, dual exhaust with a crossover, we also ordered some Edelbrock 409-series stainless Performer RPM mufflers.
Always use two wrenches to loosen the fuel-line fittings.
All that was left to track down now was a high-performance ignition upgrade for the worn-out HEI under the hood. MSD suggested its four-pin HEI computer module and all the parts we'd need to rebuild the distributor including a new coil, a cap, a rotor, and wires. After a hard weekend's work under the dualie's hood and a day at the Muffler Man exhaust shop, we pulled it back into our Tech Center to see what it could muster. Before dynoing the engine, Editor Cole did comment that the truck pulled much harder than before and that now it sounded great! He felt confident that future mileage tests would also prove that the increase in power would yield an increase in efficiency, and the truck still wouldn't pollute any more than it did when it was new.
Before we swapped out a single part, we put this '82 dualie through rigorous paces on the
So we put the dualie through another day's bashing on the Dyno-Jet and found that both power and torque increased a significant amount-not incredible numbers for a motor destined to do street/strip duty in a Camaro or Chevelle, mind you-but for a tow vehicle intended to cart around numerous project cars on a large, two-axle trailer, it was a good jump in both power and torque. Additionally, the best test, the one often referred to as "seat of the pants," yielded an impressive driving experience proving that big numbers don't always translate into real-world drivability.
As for the results on the Dyno-Jet, both power and torque grew with the torque peaking at 400 lb-ft (an increase of 76) at 2,500 rpm, while the horsepower output rose to 280 ponies (up by 92) at 4,400 rpm. What the computer printouts confirmed was that the torque came on low and stayed there throughout the whole rpm range, providing this vehicle with the necessary motivation to get the job done.
And, as a final assessment of this Edelbrock swap, the additional cooling that the combination of a trick aluminum waterpump and lightweight heads will provide means that on those long trips towing a project to the paint or chassis shop, we won't get stuck on the side of the road waiting for the temperature to come down. And, that's a good sign that our own temperatures won't be rising.
We will rebuild and reuse the original distributor with new upgrade parts from MSD.
A few hours after starting, we were ready to yank the heads. Although, big-block iron head
We used almost a whole can of WD-40 to bust loose some of the rusty fittings, but we still
|BRUTE FORCE PARTS |
|FOR POWER |
|Part ||Manufacturer || PN |
|Heads ||Edelbrock ||6049 |
|Manifold ||Edelbrock ||2161 |
|Carb ||Edelbrock ||1906 |
|Mufflers ||Edelbrock ||5525 |
|Waterpump ||Edelbrock ||8851 |
|Cam/lifters ||Crane ||133902 |
|Rockers ||Crane/Blazer ||3064 |
|Timing chain ||Crane/Blazer ||3415 |
|Pushrods ||Crane/Blazer ||1020 |
|HEI module ||MSD ||8364 |
|Cap ||MSD ||841 |
|Rotor ||MSD ||8410 |
|Coil cover ||MSD ||8402 |
|Wires ||MSD ||3118 |
|Gaskets ||SCE ||113454 |
|Spark Plugs ||Autolite ||3926 |
|Bolts ||ARP |
|Headers ||Hedman || |
While there are only a few specialty tools needed to perform such a big operation of swapp
Bump And Grunt
The Crane PowerMax cam we chose is designed for towing and good gas mileage. It's not big by any standards, and that should translate to tons of torque with very good wear characteristics for the associated parts like valve springs.
Crane H-260-2 PowerMax hydraulic flat-tappet cam PN 133901 (PN 133902 includes lifters with cam kit)
|Advertised duration: ||Int 260 || ||Exh 272 inches |
|Duration @ 0.050: ||Int 204 || ||Exh 216 inches |
|Lift: ||Int 0.484 || ||Exh 0.502 inches |
|Lobe Separation: ||112 |
We like to double-up two, box-end wrenches as shown to get extra leverage when removing st
To clean off the years of stuck head gaskets we used a Standard Abrasives disc. Then we ch
The lifter valley didn't show signs of long-term oil sludge, so we concluded that the engi
|BRUTE POWER |
| ||BEFORE ||AFTER |
|RPM ||HP ||TQ ||HP ||TQ |
|2,600 ||160 ||324 ||208 ||400 |
|2,800 ||166 ||312 ||210 ||395 |
|3,000 ||175 ||307 ||217 ||381 |
|3,200 ||182 ||298 ||229 ||377 |
|3,400 ||187 ||288 ||241 ||373 |
|3,600 ||186 ||271 ||256 ||373 |
|3,800 ||188 ||259 ||266 ||367 |
|4,000 ||185 ||242 ||273 ||358 |
|4,200 ||185 || 231 ||275 ||344 |
|4,400 ||177 ||212 ||280 ||333 |
|4,600 ||169 ||194 ||273 ||312 |
|4,800 ||157 ||172 ||272 ||297 |
|5,000 ||138 ||144 ||266 ||280 |
|PEAK ||188 ||324 ||280 ||400 |
With our impossible-to-reach bolt in the head, we lowered it onto the new SCE composition
Hydraulic cams rely on extra lubrication upon initial start-up. If you don't apply a liber
We fabbed up this cheap timing gear installer from some 2-inch steel pipe. It cost about $
Yes, this may only be a towing motor, but that's no excuse not to degree it if you have th
Just because you lubed the cam, don't forget to also coat the lifters with cam break-in lu
The 2-inch Hedman headers were the first new parts to go in. We thought this would be easi
Before bolting the new heads on, we chased each head-bolt hole with an ARP thread-cleaning
This is the outside hole that's impossible to get the bolt in once the head's on the block
The head-bolt threads get a sealant to keep water from leaking out (high-temp RTV works we
It's important to follow the factory torque sequence on any cylinder head to ensure you sp
Big-block Chevy heads use 16 head bolts of various lengths. So why is there only 15 in thi
We oiled Crane's 1.7:1 Blazer aluminum roller rocker arms and made sure that each pushrod
The stock HEI rebuild was next, and we converted it to MSD's new computer module for more
Some of the truck's old accessories had to be reused, so we cleaned parts like the thermos
The Edelbrock Performer intake manifold is equipped to use the factory choke heat tube, bu
We screwed these EGR hose fittings from the original exhaust manifold injector tubes into
Autolite spark plugs with 5/8-inch hex and gasket seats were coated with anti-seize and sc
Some last-minute, throttle-linkage adjustments to the Performer Q-Jet carb and we're ready
You can't keep corrosion completely out of the cooling system, but how about giving it som
Some of the other editors in the Tech Center couldn't believe their eyes after the first d
Automotive Racing Products (ARP)
531 Spectrum Circle
16410 Manning Way
Autolite Allied Signal Aftermarket Division
105 Pawtucket Ave.
Jeg's High Performance Center
751 E. 11th Ave
Autotronic Controls Corp. (MSD)
The Muffler Man
530 Fentress Blvd.
Rad Cap products
5236 Pacheco Blvd.
2700 California St.
Specialty Component Engineering (SCE Gaskets)
1122 West Ave. L-12 Unit 111