More power and torque for your Ford 400M is a simple intake swap away.
Let's face it, 400M Ford owners get no respect. Sure, mention the word Cleveland and watch everyone's eyes light up, but the fire dies right out when you try to include the Modified or Midland family in the discussion. This seems odd since the two motors share so many components. In fact, it can be argued that the 400M motors are nothing more than a tall-deck, stroker Cleveland. Think about it-that's all that separates the legendary 351 Cleveland from its torque-oriented 400M (try running that statement by a Cleveland fan some time). Run with the same combination of parts (heads, cam, and intake), the 400M will always make more power than a 351 Cleveland, making it a readily available and ideal classic truck powerplant. Nonsense you say? They key to the statement is that fact that one truck motor measures 400 ci and the other fancy race motor displaces just 351 ci. It doesn't take a rocket scientist to realize that if both have the same head flow, cam timing, and induction system, the bigger motor will always make more peak and average power. The key is selecting the right components for your intended application.
The test motor started out life as a wrecking yard find, pulled from the engine bay of a '
How many Clevelands out there are running around with 568 hp and how may of those make 542 lb-ft of torque? These 400M motors are capable of some serious power, but for now we will stick with some basic mods, namely the induction system. Unfortunately for 400M owners, Ford saw fit to offer the motor with only a two-barrel manifold and carburetor. True enough, the motor was designed as a workhorse, but why limit the power and torque potential with a restrictive induction system? Heck, even the tiny 289 and 302 Windsor motors came with four-barrel carbs and intakes. If any motor could take advantage of the benefits of a four-barrel carb, it was the comparatively larger 400M. In fact, it can be argued that a proper four-barrel induction system would not only improve towing power, but might improve mileage as well, providing a spread-bore carb design was employed to allow cruising on the smaller primaries. Regardless of their reasoning, the factory deuce (two-barrel intake and carb) are restrictive even on a stock motor.
Though the motor was likely a runner, we decided a rebuild was in order before running the
To illustrate the gains offered by dropping the deuce, we rebuilt a stock 400M yanked from the engine bay of a '76 F-250. The motor was in running condition, but we found a couple of bent pushrods and other evidence of abuse, so we took Demon Engines up on their offer to perform the necessary rebuild. Working with L&R Automotive (machine shop) and Probe Racing, the guys from Demon Engines were able to transform the tired 400M into a healthy stocker. In fact, the motor was treated to a piston upgrade in the form of a set of forged flat-top pistons from Probe Racing. The .030-over forged slugs were originally designed for a 351 Cleveland application, but fit perfectly in the freshly machined bores on our 400 block. The reciprocating assembly was balanced using a new 28-ounce balancer from Pro Comp. Additional changes included new rings and bearings, a new (stock) hydraulic flat-tappet cam from Elgin, and upgrading the factory connecting rods with ARP rod bolts. Care must be taken when rebuilding a motor equipped with a flat-tappet cam. The cam was liberally coated with assembly lube, ditto for the bottom of the lifters. We also added a container of high-zinc break-in lubricant from Lucas Oil before pre-lubing the 400M with a drill motor. Never start a dry engine.
After boring the block .030, L&R installed the stock crank and rods with new rod and main
We did step up in the piston department by installing a set of forged flat-top (351 Clevel
We installed a new stock 400M cam courtesy of Elgin. The cam and new hydraulic lifters wer
The original timing chain was a tad on the loose side, so we installed a new set to ensure
Here is the finished and painted short-block ready to receive a set of freshened stock 2V
Fel-Pro supplied all the necessary head and intake gaskets for our buildup.