Motorhome Dodge 440 Basic Rebuild Gets Great Horsepower and Torque
We get over 460 horsepower and 460 lb-ft out of Dodge 440 with only a simple rebuild and aftermarket camshaft.
We all know the 440 big-block is the largest-displacement V-8 engine built by Chrysler, and when it comes to a combination of torque, power, and drivability, the 440 ranks as one of the best engines ever built. Instead of utilizing a high compression ratio or aggressive cam grind for its muscle, the 440 relies on sheer size, making great power from an idle with enough torque to get even the heaviest trucks and motorhomes moving quickly. And while the Mopar 440 does several things very well, we've always felt that with a few tweaks the engine was capable of well over the 375 horsepower rating it got from the factory. Even the highest-performing factory 440, the 390-horsepower Six-Pack (or Six-Barrel) version, had a relatively mild hydraulic flat-tappet camshaft and non-adjustable rocker arms, ensuring years of smooth, maintenance-free operation. Even better, 440s are still available in scrap yards, from core suppliers, or even in running vehicles if you know where to look.
The 440 we're featuring in this build was actually in a low-mileage Winnebago motor home that was built on a '74 Dodge truck chassis. We found the engine in the local classified ads and bought the engine and transmission from the owner for a paltry $400. The motorhome had seen better days and was being scrapped, so the owner simply had no use for the engine anymore. As an added benefit, this engine (like many early to mid-'70s truck and motorhome 440s) was equipped with a factory forged crankshaft. So when we needed an engine to build as a dyno mule to test some parts, this 440 fit the bill nicely. Even better, the engine had very little wear, so it wouldn't need much in the way of machine work.
Many engines used in motorhomes now have high-mileage and are completely worn out, but some motorhomes, especially older ones, didn't see much use. The motorhome our engine was in only showed some 40,000 miles on the odometer and was only used once or twice a year for family vacations. When we disassembled the engine, we found that all of the internals were standard, and the cylinder bores were still round and straight without any ridge at the top. Since we had a set of older, standard-bore Speed Pro forged, flat-top pistons on the shelf we acquired years ago at a swap meet, this engine was the perfect excuse to keep our pistons from collecting any more dust.
The only downside to using our Speed Pro pistons was that the compression of this engine—with the stock heads and the pistons .014-inch down in the bore at TDC—would only be around 9.0:1. Since a 440 with compression this low wouldn't make enough power to impress anyone, we took the opportunity to use a set of "915" casting cylinder heads that were also sitting on a shelf in our shop. We had picked up these heads years ago at a swap meet, as well, paying only $100 for the pair. After we cleaned up the heads, we cut the exhaust seats and installed a set of stock exhaust valves from some 906 heads, a set of Comp 928-16 valvesprings, and performed a simple port-match job and valve job to make them serviceable. With a closed chamber design and a measured chamber volume of 82cc, we calculated the static compression of our 440 using the 915 heads to be 10.18:1, so our 440 will run great on pump gas.
For this engine's rotating assembly, we simply polished the crankshaft, installed ARP rod bolts and main studs, and new stock replacement engine bearings from Summit Racing Equipment. We fitted our Speed Pro pistons with stock rings and sealed the engine with a fresh set of gaskets and seals, also from Summit. As you likely can tell, we're building this 440 on a budget and simply replacing the parts necessary to make it perform properly and last, but we're not going over the top with any lightweight or exotic pieces. Using a new Melling oil pump with a factory B-Body HP oil pan and windage tray also keeps things inexpensive, but it works just fine for an engine like our mild big-block.
One area where we will definitely upgrade our 440 is with a new camshaft and lifters from Comp Cams. To enhance the power of our big-block, we chose a Comp PN 23-362-5 solid flat-tappet cam and lifter kit. This cam isn't small by any means, but it isn't a giant, either, with 0.567-inch intake lift, 264 degrees duration at .050-inch lift, and a lobe separation angle of 108 degrees. This cam is what we consider an aggressive street/strip grind, and it should wake up our otherwise stock 440. To spin the camshaft, we chose a Comp double roller timing set. For fuel injection we'd consider a different grind with a 112ish-degree LSA.
Of course, since we're upgrading to solid lifters, we also need to install adjustable rocker gear, so we installed a set of Comp's Ultra Pro-Magnum adjustable roller rocker arms. The Ultra Pro-Magnum rocker kit comes with the rocker arms, adjustors, new shafts, and the necessary spacers. We've used these rockers before and found them to be some of the best rocker arms on the market for the price, and we like the fact that the Comp rockers utilize ball-ball type pushrods. These parts might be overkill for what we're building, but the durability makes it worthwhile.
For induction, we will use an older Mopar Performance M-1 aluminum single-plane intake manifold that we picked up at the Mopar Nationals swap meet. The intake was priced so well, we couldn't pass it up. Topping the M-1 intake, we'll install a new Holley Ultra HP 950 cfm double-pumper carburetor. This carb is actually the most expensive single part we're installing on our engine, but it will greatly ease tuning while the engine is on the dyno. In our experience, the Ultra HP-series carbs from Holley perform flawlessly right out of the box, needing very little tuning just to match the carb to the particular engine.
With the engine on the dyno at Auto Performance Engines (APE), we bolted on a set of APE's Hooker Super Competition dyno headers and an MSD pro-billet dyno distributor. We like the MSD distributor because it makes changing ignition timing curves easy, though for cost considerations a Chrysler electronic distributor would also be sufficient for this engine. For testing purposes, using the known good headers and distributor provided by APE ensure we won't have any issues while tuning this engine.
Prior to firing our 440, we poured in six quarts of Comp Cams 10W-30 break-in oil and primed the oil system. Flat-tappet camshafts require special lubricants to break in properly, and Comp's oil contains the necessary additive package to ensure our cam performs properly for the life of this engine. After starting the engine and running it through a break-in cycle, we let it cool down, double-checked valve lash, and were ready to make some test pulls.
After making a couple of ignition timing changes, we found our 440 likes 37 degrees of total advance, and the air/fuel ratio of this engine was nearly perfect with our out-of-the-box Holley 950. Our peak power with this combination was 460.6 at 6,000 rpm, and peak torque was a stump-pulling 466.9 lb-ft. As we further develop this combination, we'll optimize our 440 by testing a variety of parts on the engine. For now, however, we're happy to have made a whole bunch more power than a factory 440, while sticking to a very conservative parts budget.
Our big-block dyno engine shows that the right combination of a few aftermarket parts, built with a conservative budget, can make plenty of power.