Richard Holdener
November 1, 2009
Is the 400M a real contender? All it takes is the right bolt-ons and you have the makings of a serious stroker Cleveland.

If we were to query a group of Ford enthusiasts-not just the late-model crowd-about the performance potential and popularity of the 351 Cleveland, we'd be overwhelmed by stories and historical events that helped shape Ford performance.

Though short-lived, the Cleveland engine family was successful in nearly every form of motorsports, from NASCAR to Pro Stock, to say nothing of a serious presence on the street. And let's not forget the success of the Cleveland-headed Boss 302 in Trans Am racing.

Ask the very same group of enthusiasts about the 400M and chances are you'll hear nothing but crickets. If you do hear anything, it will be disgruntled rumblings about low-compression smog motors and engines suited for nothing more than towing-and did someone say boat anchor?

Like most performance build ups, the 400M came from humble beginnings, meaning it was wasting away in a nearby wrecking yard. Used basically as a rebuildable core, this motor was actually a runner (after replacing one bent pushrod).

This dichotomy seems odd, since the 400M is really nothing more than a large-displacement 351 Cleveland in disguise.Admittedly, MM&FF has not done much with the Cleveland series engine, mainly because there was so much to talk about with the 302 and 351W, and of course the wonderful world of modular engines. But with a great head design and 351 or 400 ci (not to mention a big surplus of parts), it's time to explore how much power we could make.

Maybe the trick is to ask our Cleveland enthusiasts about an aluminum-headed, tall-deck, stroker Cleveland? Misrepresentation of the much-maligned "M" you say? Read on.

The fact-checkers among you may point out that the low-compression smog motor is an accurate description of the 400M. "Boat anchor" may be a tad harsh, but it is true that the 400M was primarily used in full-sized vehicles and truck applications where torque was the primary concern. It is also true that in 1977, the 400M offered a mind-blowing 173 hp at 3,600 rpm and peak torque production of 326 lb-ft at a diesel-like 2,000 rpm

Thanks to Demon Engines and L&R Automotive, the two-bolt block was bored 0.030 over and stuffed with the stock crank (previously turned 0.010/0.010) and factory connecting rods. The stock forged rods received ARP rod bolts to ensure strength for those 6,500-rpm blasts.

Given a production range from 1971 to 1980, combined with a static compression of 8.4:1 (9.0:1 in 1971), the 400M was indeed a low-compression, smog motor. Oddly enough, it is this lack of desirability that makes it such a desirable commodity. Confused? The lack of interest by Ford fans means there are usually plenty to be found in wrecking yards, though it is getting tougher and tougher to find vehicles of this vintage. We've found complete (running) 400M motors for as little as $120!

Once you have a complete (and hopefully running) motor, the level of power you require will dictate how far you dig into the motor. The short and sweet route is to replace the factory two-barrel carb and intake with a four-barrel equivalent (from Edelbrock or Weiand), add a set of tubular headers (for your chassis) and possibly a mild RV-type cam (any cam ground for the Cleveland family will fit the 400M). If everything else is in working order, you can expect a solid power gain from these minor mods.

Taking things a little farther, you can step up in cam profile (to something just over 220 degrees of duration at 0.050) and perform a little port work to the 400M two-barrel (2V) heads. Combine the cam swap with a slight milling to increase the static compression ratio above that normally associated with forced induction use, and you can expect to literally double the original factory power output.

Expect torque production to easily exceed 425 lb-ft using a dual-plane intake and mildly ported two-barrel heads. If you happen to have a set of four-barrel (4V) heads, especially the more desirable early quench heads at your disposal (they are difficult to come by), they will really wake up a 400M thanks to a combination of additional airflow and static compression, though intake choices for the bigger four-barrel ports are all but nonexistent (more on the cure later).

Probe Racing supplied the necessary forged pistons for our 400M build up. Basically flat-top, 351 Cleveland slugs, though still down in the hole nearly 0.060, the flat-top pistons nonetheless increased the static compression ratio of the 400M over the factory dished pistons.

For our buildup, we started with a fresh short-block supplied by Demon Engines. L&R Automotive was kind enough to transform a used core into a workable short-block using a combination of factory and aftermarket components. To minimize costs, we reused the stock block, crank, and rods, but the block and factory connecting rods were treated to some much-needed machine work. The block was bored 0.030 over to accept a new set of flat-top forged pistons.

Lucky for us, the compression height of the 400M pistons is very close to the 351C. The slight difference (1.624 versus 1.650) between the factory 400M pistons and our forged 351 Cleveland pistons from Probe Racing decreased the deck clearance and helped increase the static compression ratio.

The forged flat-top pistons were installed on the stock (reconditioned) rods. Aftermarket rods for the 400M are few and far between since the tall-deck 400 motor requires the use of 6.58-inch rods (compared to 5.78 for the 351 Cleveland). The factory rods were treated to beam polishing and a set of ARP rod bolts. After all, we planned on running the motor well past 3,600 rpm (the power peak of the original motor). Naturally the 400M short-block also received new rings and bearings courtesy of Demon Engines and L&R Automotive.

Here is our freshly painted 400M short-block ready to accept the stock cam and two-barrel heads.

In factory trim, the 400M produced peak power at just 3,600 rpm and offered its torque peak at 2,000 rpm. Since horsepower is nothing more than a mathematical representation of where there the torque curve occurs, shifting the torque curve higher in the rev range will greatly increase the peak horsepower number. We chose not only wilder cam timing compared to stock, but further upgraded the power potential by swapping out the hydraulic flat-tappet cam for a pair of solid roller profiles.

While solid rollers are usually reserved for race motors, we first chose a street roller from Crower Cams. With slightly milder ramp rates than a race roller, the street roller was much more parts friendly and would require less maintenance over the long haul. The roller profile allowed us to have much more aggressive ramp rates than a flat-tappet grind. What this meant was that we could have our power with less duration (measured at 0.050). Basically, the solid street roller allowed us to make more power with less cam.

The Crower street roller offered a 0.570-/0.572-lift split, a 234-/244-duration split (at 0.050) and a 110-degree lobe separation angle. Crower also supplied the matching solid-roller lifters to work with the cam. It is certainly possible to exceed the 500hp mark using a solid or even hydraulic flat-tappet cam, but you'd have to run a minimum of 10-15 degrees more duration than the roller to make equivalent power.

Making sure we maximized the cam profile was a set of 1.73:1-ratio aluminum roller rockers from Comp Cams. Naturally the factory stamped steel rockers (non-adjustable on the 400M two-barrel heads) were not adequate for our needs, nor would they work as the Pro Comp heads were set up to accept rocker studs and guide plates.

Solid-roller cam choice No. 2 came from the Ford cam experts at Cam Research Corp (www.camresearchcorp.com) in Englewood, Colorado. You might recognize the Cam Research name from the Engine Masters competition. These guys know Ford cam timing and only bad luck has kept them out of top finishes, if not outright wins in the competition.

After explaining our 400M combination the staff first asked about our choice of static compression ratio. Even after swapping the factory dished pistons for flat tops and reducing the combustion chamber size, we were still left with a static compression ratio of just under 9.5:1. Since this wasn't ideal for performance use, Cam Research designed a profile to optimize performance with the reduced static compression in the desired rpm range.

To illustrate what the stock motor had to offer, we installed a stock 400M cam (from Elgin) and new hydraulic flat-tappet lifters (from Comp Cams). The factory Ford 400M featured a cam retaining plate to properly locate the cam.

When it comes to cam timing, it's relatively easy to add power by increasing duration. The downside is that the extra top-end power comes with a loss of torque lower in the rev range. The difference between selecting an off-the-shelf cam and having a shop like Cam Research custom-grind a cam for your specific application is a ton of extra power. You know you've done something right when you install wilder cam timing and have the power increase throughout the entire rev range.

Were this a 400-inch Windsor motor, we might be tempted to choose a dish piston, but the 400M two-barrel heads featured large (as much as 79cc) combustion chambers. These large chambers required a flat-top piston to produce a reasonable compression ratio (near 9.0:1).

All of the later two-barrel (and four-barrel) heads have a reputation for increasing the likelihood of detonation. The open chamber heads (including those on the 400M) were designed to lower the compression ratio, but the lack of a proper quench area actually makes them more sensitive to detonation. Thus, the static compression ratio should be kept lower when running factory open-chamber heads compared to the more desirable closed-chamber or quench heads

A factory-style timing-chain assembly was then installed over the stock cam and retaining plate.

We cured this situation with the installation of aluminum Cleveland heads from Pro Comp. The Pro Comp heads feature all of the positive aspects of the Cleveland family, poly-angle valve configuration, including the large 2.19/1.71 stainless steel valve combination.

You may be wondering why we chose a set of aluminum heads for our low-buck build, but the Pro Comp aluminum heads can be had for about the cost of a set of used factory four-barrel heads. For roughly a little more than the price of of Windsor heads, Cleveland (and 351/400 Midland) owners can enjoy the benefits of a set of bolt-on aluminum heads. Not just aluminum heads, but performance heads that are head and shoulders above either of the factory two-barrel or four-barrel heads. It would take a serious set of ported four-barrel heads to equal the flow potential of the Pro Comp Cleveland heads, and you'd still be stuck with heavy cast-iron heads with relatively huge (and potentially lazy) port volumes. Airflow is one thing, but it is always better when a given flow rate comes through a smaller orifice.

To put this into perspective, the intake-port volume on a set of CNC-ported Pro Comp Cleveland heads is less than a set of stock, as-cast four-barrel Cleveland heads. These smaller ports flow as much as 50 to 60 cfm more airflow than a stock four-barrel port. In addition to the reduction in weight and improvements in airflow, the Pro Comp heads also came with a 2.19/1.71 stainless steel valves. Complete heads come with your choice of valvesprings for the intended cam (flat-tappet or roller), chrome-moly retainers and 10-degree locks. The heads also come with studs and guide plates to properly orient the pushrods.

Impressive right out of the box, our Pro Comp Cleveland heads were given a once over by Bryce Mulvey of Dr. J's. Bryce worked his magic on the heads by applying not only a precision valve job, but further improving the flow potential. As received, the unfinished Pro Comp Heads flowed 325 cfm on the intake and 228 cfm on the exhaust. After Bryce completed the porting and valve job, the flow numbers jumped to 348 cfm on the intake and 252 cfm on the exhaust (all measurements taken at 0.800 lift at 28 inches). What the additional airflow does is allow you to reach a given power level with milder cam timing. Thus you have a powerful engine combination without the usual idle quality and drivability issues associated with wilder cam timing.

The two-barrel heads used on the 400M featured 79cc combustion chambers, which further lowered the static compression ratio on the stock motors. When combined with the dished pistons residing well down in the hole, the result was a less-than-optimum 8.4:1 compression.

One of the areas of concern with the tall-deck 400M is the intake manifold. Both the 351M and 400M motors were factory equipped with two-barrel intakes. There are a few different aftermarket manifolds available for the 400M, but both the Edelbrock Performer and Weiand Action Plus manifolds were designed for milder applications equipped with the factory two-barrel heads. Given the success in Engine Masters Challenge competitions with legendary builder John Kaase, the boys from CHI designed and cast a high-performance, single-plane intake designed specifically for use with their aluminum Cleveland heads on the tall-deck 400M.

Lucky for us, the port configuration on the intake was close enough to the Pro Comp heads to allow us minor port-matching to facilitate use of the CHI 400M intake on our test motor. The CHI 400M intake came to us on loan from the Cleveland experts at MPG heads in Englewood, Colorado (www.mpgheads.com).

Like all two-barrel heads, these featured the positive-stop, bolt down (non-adjustable) valve train for use with the hydraulic flat-tappet cams. We ran the stock two-barrel heads with the stock stamped-steel rockers (from Elgin).

MPG also supplied a set of adapter plates to facilitate use of standard 351 Cleveland intakes on the 400M. The spacer plates were necessary due to the deck-height difference between the 9.2-deck 351C and the 10.3-deck 400M. Its custom spacers allowed us to run an Edelbrock Performer RPM Air Gap (351C) intake on the 400M. These same spacer plates (if the ports were sized properly) would allow you to run any two-barrel or four-barrel manifold currently available for the 351C.

We turned to Holley for carburetion, in the form of a 750hp Street carb. The 750 Holley was further enhanced with Percy's Adjust-a-Jet system. The Adjust-a-Jet system allowed external jetting changes to the Holley, which made dyno testing even easier.

With the majority of the hard parts taken care of, it was time for the minor components. These included the ignition, exhaust and water pump. Ignition chores were handled by a Ford distributor (pulled from a 514 crate motor) along with a Pro Comp wire set. Though not required for this application, the Westech dyno was equipped with an MSD Digital 7 ignition amplifier.

Since the carb was missing when we sourced the motor from the wrecking yard, we simply installed a 500-cfm Holley two-barrel Westech had on hand.

Our exhaust needs were handled with a set of Hooker Super Comp headers. The 1 7/8-inch headers were designed for an early Mustang chassis and offered plenty of flow for the 400M application. The Hooker headers were run through 18-inch collector extensions, while Meziere supplied an electric water pump for our 351C/400M application.

Additional components included a 28-ounce balancer from Pro Comp, ARP 1/2-inch Cleveland head studs and Fel-Pro head and intake gaskets. Since the idea was to run the 400M in (near) stock trim, and then again after swapping over the heads, cam and intake, we required a few sets of gaskets to perform our make over. A set of Ford Racing finned-aluminum valve covers spiced up the freshly-painted 400M (Pro Comp also offers cast-aluminum Cleveland valve covers), while Lucas oil products (oil, break-in lubricant and octane booster) ensured our street motor had plenty of octane and lubrication. The stock cam was liberally coated with moly-based assembly lube and we added a container of high-zinc, break-in additive from Lucas Oil before pre-lubing the 400M using a drill motor on the oil pump driveshaft. Oil pressure from the drill motor was provided until we had oil present in every rocker arm.

The first order of business was to run the 400M in (near) stock trim. Changes to the factory Ford included the set of flat-top pistons (increasing the static compression ratio from as low as 8.4:1 to near 9.0:1). This was accomplished by combining the flat-tap pistons with an increase in bore diameter (4.00-4.030), decking the block and altering the compression height of the pistons. From the factory, the dished pistons were down in the hole nearly 0.060 (after 1971). This helped dramatically reduce static compression on the stock motors. Though we installed the flat-top Cleveland pistons from Probe Racing, they were still 0.060 down in the hole.

Wanting to optimize valve train geometry, we installed a set of 1.73 aluminum roller rockers from Comp Cams. The stock stamped steel rockers have no business on a performance motor.

Other changes to the stock motor included running with long-tube headers, a Holley 500-cfm two-barrel carb and an electronic ignition. Basically we had a high(er) compression two-barrel 400M with headers and a larger two-barrel Holley carb.

Equipped with the stock two-barrel heads, cam, and two-barrel intake, the 400M managed to produce peak numbers of 265 hp at 4,100 rpm and 412 lb-ft of torque at 2,900 rpm. The 400M was obviously tuned for low-speed torque, as torque production from the 400M exceeded 400 lb-ft from 2,000 rpm (and likely lower) to 3,200 rpm. The stock cam, heads and intake manifold literally choked off power production above 4,500 rpm.

With our baseline out of the way, we installed the performance parts. On went the ported Pro Comp aluminum heads from Dr. J's, the street roller cam from Crower Cams, and the Performer RPM Air Gap/spacer-plate intake combination from MPG. The Pro Comp heads not only improved the airflow over the stock two-barrel heads, but also increased the static compression ratio by reducing the combustion chamber volume from 79 cc on the stock two-barrel heads to 75 cc.

The taller deck height of the 400M required intake spacers to allow use of a 351C intake manifold. MGP supplied the necessary spacer plates for use with the Pro Comp head ports (different than either factory two-barrel or four-barrel).

The roller cam from Crower was augmented with solid-roller lifters and a set of 1.73 roller rockers from Comp Cams. Why go to all the trouble of installing a good cam only to reduce its efficiency with the stock stamped steel rockers? This new combination also required a pushrod change, as the adjustable valve train required a 0.050-inch longer (hardened) pushrod than the stock 400M units. The new combination was fed by a 750hp Street carburetor equipped with Percy Adjust-a-Jets. This slick feature basically allowed external jet changes to dial in the air/fuel mixture.

After minor jetting and timing sweeps, we were rewarded with a jump in peak numbers from 265 hp and 412 lb-ft to 489 hp and 502 ft-lb of torque. As expected, the new combination produced these numbers higher in the rev range than the stock components. Where the stock combination produced peak power at 4,100 rpm and peak torque at 2,900 rpm, the wilder combination produced peak power at 5,900 rpm and peak torque at 4,100 rpm.

Though designed for use with the new Edelbrock Cleveland heads, we chose to run the Edelbrock Performer RPM Air Gap intake on the 400M. A little port matching of the spacer plates was necessary to facilitate the test, but we've always had good luck with the Air Gap intakes on other applications.

The next order of business was an intake swap. Though we suspected a dual-plane intake was the best choice for a street motor, we wanted to see how well the CHI single-plane performed. Off came the RPM Air gap and aluminum spacers plates, and on went the CHI. The CHI intake required use of the lower valley cover plate employed with the spacer plates, but the intake swap was very straightforward. The great thing about working on Cleveland motors is that intake swaps don't require removal of the distributor. Pop off the old intake, pop on the new one, and you're ready to run.

The CHI intake was equipped with a 4,500 carb flange, so we installed a two-circuit Holley 1150 Dominator carb. A tad overkill on this application, the huge carb looked pretty menacing on the aluminum-headed 400M.

Equipped with the CHI intake and Dominator carb, the peak power numbers jumped to 529 hp and 506 lb-ft of torque. Compared to the dual-plane intake, the single-plane CHI improved both peak power and torque, though the single-plane did lose out to the dual-plane below 4,300 rpm by as much as 35 lb-ft.

In exchange for the losses down low, the single-plane improved the power output by as much as 45 hp. For this combination, the choice would come down to the intended application. The dual-plane would work best for a daily driver, but the single-plane would offer much better track performance.

400M-Stock vs Cam Research/RPM vs Cam Research/CHI
This graph illustrates the difference between the baseline run and the two intakes equipped with the custom Cleveland cam from Cam Research. As with the smaller cam, the dual-plane intake offered better low-speed power (up to 4,300 rpm) but fell off thereafter. Equipped with the dual-plane and new cam, the 400M produced 528 hp and 525 lb-ft of torque. After installation of the CHI intake, the peak power numbers jumped to 568 hp and 542 lb-ft of torque. Those are big numbers from a 9.5:1 400M boat anchor.

With our first upgrade a success, we decided to install the custom roller cam from Cam Research. The Cam Research profile increased both the lift and duration figures compared to the Street Roller cam from Crower. The Cam Research cam offered 0.726 lift and dual-pattern duration figures of 250/254 degrees at 0.050. The cam also featured a tight lobe separation angle of 106 degrees. Looking just at the specs, you might be tempted to dismiss the cam as excessive, but just check out the power gains and you'll realize that there is much more to the cam grind than simple lift and duration figures. While we'd expect additional power gains from the increased duration, what really surprised us was that the Cam Research profile improved the power output everywhere, from 3,000 rpm to 6,500 rpm.

We bolted the Edelbrock RPM Air Gap intake back on, along with the 750 Holley, and with the Cam Research stick stuffed in, the peak numbers jumped from 489 hp and 502 lb-ft of torque with the Crower cam, to 519 hp and 519 lb-ft of torque. These peak numbers were further increased to 528 hp and 525 lb-ft of torque with the installation of a 1,000-cfm Holley carb (to replace the 750 Street).

The final test was to run the new cam with the CHI single-plane intake, and boy, did this combination work well. How does 568 hp and 542 lb-ft of torque sound? Remember this was all with a static compression ratio of just 9.5:1. I guess the aluminum-headed, tall-deck, stroker Clevelands will be getting a little more respect.

Airflow Data-Pro Comp Cleveland Heads:
IN/EXIN/EX
LiftProDr. J's
0.05031/2240/28
0.{{{100}}}66/4678/58
0.{{{200}}}127/95149/99
0.{{{300}}}183/129217/135
0.400225/161273/169
0.500263/182318/209
0.{{{600}}}291/207335/231
0.700314/219343/247
0.800325/228351/253