George Dulcich always liked '71 Chargers. He drove one while in college. That particular car got away nearly 15 years ago, but the love of Chargers stuck with him. According to George, the '71 models were the pinnacle of pure performance style-the final punctuation of the muscle car era. One look at his current '71 R/T pictured here and it's hard to contemplate an argument. High Impact Paint, bold graphics, factory front and rear spoilers, Rallye wheels, radical louvered power bulge hood...the list goes on.
When George came across this R/T it was already an older restoration, having been used as a daily driver in the Los Angeles area for some time. The car was solid, functionally, and priced to sell, so George made a deal.
Although clean, the R/T's paint was faded, dinged and chipped. George knew how to handle a Binks spray gun, so he worked the flaws and blended-in the needed repairs to the lacquer paint. The bumpers, showing the worst of the existing paint, were pulled, blasted and resprayed in the matching Green Go paint, which the seller graciously provided in the deal. Finishing with a cut and machine buff job, George brought the finish back to its fresh-shot glory, for less than the cost of a pro car grooming.
With appearances back to showfield standards, making the car usable for open road touring was next on the agenda. The transmission was upgraded with B&M components and fitted with a Gear Vendors' overdrive for relaxed high-speed cruising. To add to the utility of the 29-year-old beast, a four-row core was fitted to the stock radiator, and a Mopar electronic ignition found its way onto the 440. All in all, the Charger does everything a great driver should.
The one unknown quantity is the 440 Magnum under the hood. The heavy rods, backed by the correct serial numbers up top and below, confirm that this is the original numbers-matching mill. The engine had obviously been detailed, and the seller confirmed that it had been rebuilt. The good compression and lack of blow-by would support that claim.
We set a dial indicator to the intake side of the camshaft and read 0.299-inch lifter rise, which gives 0.4485 inches at the valve, or within 111/42 thousandths of stock. On the exhaust side, the cam checked at 0.305 inches for .4575-inches of valve lift, again right at stock 440 Magnum specs. With this we can be fairly sure we are dealing with a stock-cammed 440. Up top is the original 440 AVS, feeding the stock iron intake manifold which rests on stock #346 heads. Likewise, the exhaust system is the stock cast iron manifold/dual exhaust set-up. Even the mufflers are stock O.E. 440 resto pieces.
The things we didn't know about were the mileage since the rebuild, compression ratio, cam phasing, and the other little things that are impossible to get a handle on unless you've turned the wrenches yourself. Judging from the normal carbon build-up under the heads of the intake valves, visible from down the ports, the engine has clearly turned some street miles since being pulled apart. That said, the engine pulled just about what we'd expect from an average stock 440 street engine.
What, if anything, we thought, could be done to improve the performance of this stock engine without having to go deep inside? Headers would be a huge performance boost, but the installation and subsequent pipe hook-up is not the kind of thing we had in mind. No, we wanted to look at simple bolt-ons which most anyone could accomplish in under two hours, and change back just as quickly if so desired.
In the realm of tinkering for more power, the pitfall is to be unable to quantify progress. It's easy to convince yourself that those muffler clamps added 20 horsepower. So to do this right we knew we'd have to evaluate each change, and that requires dyno or drag strip testing. We decided upon the chassis dyno at K&N Engineering (yes, the air filtration people), who have an extremely accurate and repeatable setup. The fact is, with a street driver on the strip, we can see our times change 3-4 tenths in the course of a day, and a like amount based on driving style. Sure, a true and consistent drag car is best evaluated on the strip, however, for testing on a street car, once strapped onto the Dynojet with its repeatability to within a horsepower, there's no place to hide from the truth.
It's easy to hit the dyno with an engine that runs like a pig, timing a mile out, worn plugs, burnt wires and all, then fix what's obviously broken and bask in the glory of big power gains. Now, we're not goofy when it comes to turning a wrench. You won't be able to twist off the distributor and change the plugs to gain forty horsepower. We wouldn't be driving this car if that hadn't already been done. This Charger is already fairly well tuned for what it is. To ensure that our 440 would deliver its best before making the trip to K&N, the plugs were swapped for a fresh set of Accel units, and we cut a new set of Accel wires. The timing was correctly set to 36 degrees total advance (mechanical advance fully in; vacuum advance disconnected), and a new paper air filter installed.
On The DynoWith the car strapped to the K&N chassis dyno, we worked to establish a baseline. First we made a few runs with our stock package to establish the optimal ignition timing. As expected, our best-guess setting of 36 degrees total proved to be optimal, and we would retain this setting for the remainder of our testing. Since we had a B&M Holeshot torque converter, testing below 3000-3200 rpm was not possible because the torque converter would flash to at least this rpm off the roll when stabbing the throttle on the dyno. Looking at the dyno readouts it was clear that the stock engine combo was producing peak torque below our minimum recordable rpm level, making it impossible to obtain a peak torque reading in testing. Peak torque was at an rpm low enough to be off the bottom of our chart, therefore, we will report only the horsepower numbers. If the horsepower is up at any given rpm, obviously, so is the torque at that rpm.
For the purposes of getting the most realistic numbers, each test shown is the most representative of a minimum of three pulls. The highest and lowest pulls are thrown out, and if there were any anomalies, the tests were run again. Our baseline run is recorded in Test 1. Peak horsepower was 225.1 at 5000 rpm-a typical rear wheel number for a stock 440. With the stock 440 Magnum valve springs of unknown mileage, the beginning of valve float was clearly audible at 5200 rpm, putting a definite ceiling on our useable rpm.
Air FiltrationOur first test was with the stock dual snorkel air cleaner and a replacement paper filter. Replacing the air filter involves spinning one wing nut, so this was to be our first mod. We decided to change the whole dual snorkel filter box and go to a 360-degree open element air cleaner-the typical 14-inch chrome air cleaner with a K&N filter. The outcome is recorded in Test 2. It shows that the dual snorkel is not enough even with a stock 440, with a maximum gain in our test of over 10hp at the rear wheels and more power throughout the rev range.
What if you don't want to toss that stock dual snorkel you scoured the swap meets for? For our next test we tried the dual snorkel with a K&N replacement filter inside, but with the old-timer's trick of flipping the air cleaner lid. The result was a power curve identical to that shown in Test 2. A K&N #E1530 element is a direct replacement for the stock filter in the stock dual snorkel can. The stock housing can be run, and with a flip of the lid it'll move air as well as a wide-open element. We used the K&N open air cleaner for the rest of our tests.
Carb SwapsSo far we had stuck with the stock '71 AVS in purely original form. The 440 Magnum AVSs were of a square bore design, with 1111/416-inch throttle bores all the way around. The standard 440s, 383s and 340s made do with a smaller version of the carb, with 171/416-inch primaries. Our 440 Magnum's AVS was, of course, the large version, with a flow capacity of 750 cfm. Since AVSs are getting old and are increasingly difficult to find in the large version, we thought we'd test a couple of alternatives. Indeed, our own AVS had suffered from a stripped fuel inlet fitting, which we repaired by tapping to a pipe thread. With other types of damage, the repairs may not be so straightforward, so let's look at the most logical replacement alternative.
Closely related to the AVS, although the design pre-dated it, is the Carter AFB. Although it's an older design, the AFB is still being produced under a couple of different labels, and new carbs as well as parts are readily available. The two designs are so similar that the AVS is typically mistaken for an AFB. The biggest difference is that the AVS uses an adjustable spring-loaded air door above the secondary, with a fuel spray bar in the secondary side, without a conventional venturi. In contrast, the AFB uses a conventional booster and venturi in the secondary, with a non-adjustable counterweighted air valve below the booster. The AVS also has three-stage metering rods, as opposed to the AFB's two-stage rods. Although the AVS three-stage rod set-up can be fitted to the AFB if the AVS's rod covers are used, unfortunately no one makes them anymore.
Since it is the most logical replacement carb, we picked up a new Carter Competition Series AFB in the same square bore 1111/416-inch 750 cfm size as the old AVS. The swap couldn't have been simpler, owing to the similarity of the carbs: the fuel inlets are in the same place (and even interchange); the flange patterns are the same; the linkage clears all of the manifold obstructions; the factory throttle and kickdown linkage bolts up in the same position; unlike some other aftermarket carbs, it doesn't interfere with the coil in its stock manifold-mounted location; the vacuum fittings are in the same place; and the stock air cleaner housing fits. The only thing closer would be to buy a brand new AVS.
We just did what the typical Saturday enthusiast would do when shelling out for a new carb. We took the AFB out of the box and bolted it on. The result is shown in Test 3-definitely down some on the old AVS. The AVS had the advantage of being factory calibrated specifically for the stock 440 Magnum, while the AFB has less specific "universal" calibration. No doubt with some jet changes the AFB's results could have been improved, but we decided to let the chips stay where they fell.
While we had the AFB bolted on, we decided to try a 1-inch carb spacer. Not because we saw any specific benefit with regard to the AFB in particular, but we wanted to see what it would do on a stock manifold on a stock engine. The open carb spacer will increase the plenum volume and more freely join the left and right sides of the essentially divided stock manifold (the thick stock carb base gasket acts as a short spacer essentially doing the same thing). Typically, open spacers will help increase top end power. On hotter engine combinations, the effect can be drastic, but we are dealing with a stock 440 here, so we didn't expect miracles.