IT'S ALIVE: 'MERICAN METAL MENACE SPARKS TO LIFE
‘Merican Metal Menace sparks to life on the dyno
Through this seemingly never ending journey through the design, discovery, prep, assembly and tuning of a 407 ci AMC V-8, which we dubbed the 'Merican Metal Menace (MMM), our target was 400+ hp and 500 ft-lb of torque, while holding a smooth idle and running on pump gas. Target hit, our bucket of tips and tricks has run dry, and the numbers are in, as we close the last chapter on MMM and let it fulfill its destiny powering “Stinky Jeep” effortlessly down future trails.
The therapeutic journey of taking the motor, that was originally scored from a tired Jeep J-truck. and making it into the trail terror you read about here (and at www.suncruisermedia.com/4wdrive) was not achieved singlehandedly. Comp Cams, Edelbrock, Molnar Technologies, BHJ, Fel-Pro, Diamond Pistons, ARP, Total Seal and Summit Racing all took the time to listen to our goals and help devise a plan to get there. Without our machine shop of choice (K&S Machine), our lofty goals would have been all for naught. The proper machine tolerances are just as critical when building a daily driver, as they are a top fuel drag motor, it’s knowing what those tolerances should be that counts. K&S Machine in Kelowna, BC, did an exemplary job understanding our parts collection fitment allowances and not only machined, but also balanced them to spec. These are not the only engine services offered and we took them up on one of the most critical they offer; a break-in and test and tune on an engine dynamometer.
We can’t stress enough the importance of a proper engine break in procedure with a fresh mill. Wiped out cams and cooked bearings on freshly built motors is a dream killer and having to call “mulligan” on a build you just dropped between frame rails of your truck is enough to make you kick a
kitten. But it doesn’t have to be this way… for a measly $600 you can drop your fresh steel steed off and have the K&S crew in lab coats strap it to the dyno for a proper break in.
K&S took our MMM and rolled it into their dyno cell after months of our puttering and fiddling around assembling the earth shaker. They carefully hooked it up from balancer to bellhousing, complete with a new MSD starter to help turn the 10.75:1 CR motor over. They selected from their plethora of parts a QuickTime 750 CFM carb they run for break in and bolted on a set of Headman long tube headers awaiting our arrival. Walking into the cell we were greeted with a temperature and humidity controlled clean room with a “Land & Sea” dyno strapped to the back of MMM. What a glorious sight indeed. With sensors and air flow devices emanating from the MMM like a NASA flight deck launch, we were told that the dyno had just been calibrated and we were in for fun today.
Some call the experience of starting an engine for the first time like watching “Your child come into the world”… not bloody likely… freak. You yearn for your child to be good, and noble, and just. We were hoping for Chuck Norris the V-8 to put his smoke out on his arm and start kicking ass in the cell. This isn’t the “Merican Metal Menace” because we like puppies and own a snuggie. We were about to watch Victor Frankenstein bring The Monster to life… I guess that makes us Igor. Dammit.
Keith and Stephen from K&S carefully prelubed the motor with AMSOIL’s finest Break In lube and ensured we had proper oil pressure while spinning the crank with a ratchet to make sure any air pockets were out of the system. The DUI dizzy spec’d for the MMM was stabbed back home and a crude baseline of timing was set. A fresh fuel cell of 92 octane against the wall was made ready as switches were flicked in anticipation of life.
“Click” Fuel pump.
“Click” Room fans.
“Click” Water pump.
The last “Click” brought a starter “whirr”, which could have been be measured in millennia for us, before the belch of half burnt fuel coughed its first flame into the collector pipes at the back of the cell. The Menace was awake. WHAT HAVE WE DONE!!!
A flurry of activity surrounded the cell as our Flat Tappet Hydraulic Comp XE262 cam’s life on this earth depended on the next several minutes. Base timing was set at a moderate 8-degree until we were sure all was well. Steady oil pressure and fluctuating RPM are required to not only seat the Total Seal rings for a long life, but also keep as much oil on, in and around the camshaft and lifters for them to wear in a proper pattern and harden. For the next half hour, our time was spent watching Keith and Stephen earn their
keep in certifying our investment as “alive and well.”
To be honest, the rumble was not what we had expected out of an open header motor with the parts we had thrown at it, it was… well… good? No engine shake or wickedly lumpy idle. Oil pressure stayed a constant 60-psi at anything above 1,500 rpm. It was “fine, I guess?” My desire for a nasty idle stems from my drag racing gene. We were talked out of the massive bump stick we wanted by Comp Cam’s techs in order to keep the power at a useable rpm for an off-road rig. We had trusted their judgement, and believed in their wisdom. All we could do was wait.
Another “click” shut the ignition off and the Menace closed its eyes for a short nap. A nut and bolt check of the hot and smelly motor revealed nothing out of the ordinary. Timing was set, air/fuel ratios looked good, oil pressure was looking great; epic for an AMC engine, as they are known for historically low pressures.
It was time for a quick break and then get some real numbers out of the MMM.
Our goal for the day was not to see what kind of peak numbers we could eek out of the motor, as this has no bearing on what will actually happen in the Jeep, it was about getting some basic numbers and a torque curve for matching components like gear ratios and transmission choices. Tuning the Menace to squeeze the final hp was moot as we were going to run Holley’s Terminator EFI, not a carb; the long tube headers in the dyno cell would be swapped for a set of Doug’s Original shorty units that we can actually snake exhaust through the suspension without assistance from a ball peen; the water thin race oil will be swapped for Amsoil’s 10-30wt Z-Rod lube for longevity; and accessories like alternator, water pump, air compressor, power steering pump and what ever other parasitic loss items yet to be attached will alter our hard work. In a nutshell, we were going to make a few pulls to get some numbers, but there was no point tuning it
to perfection in this form.
As the lab coats came back from their break, Keith sat at the dyno cell controls and merely raised an eyebrow in our direction. No words had to be said as we nodded in acknowledgement, it was time to awake MMM once again. Familiar “clicks” ended with gurgle as the Menace held fast in the engine stand. The only sign of life was the spinning crank pulley and watching the rotor of the distributor spin under the clear cap. Keith removed himself from his pilot’s seat and made his way into the dyno cell for a last check. The all clear was given and the room doors were sealed for the run.
At 36-degrees of total timing dialled in and the engine up to temperature, Keith calmly moved the hand throttle to the “wide open” position and engaged the dynamometer. Our eyes were shifting between the computer screen, gauges and engine at a pace that only time lapse filming could catch. Excitement, fear, anticipation and feelings of doubt gushed through our veins as the lone digital gauge plated squarely in the middle of the screen rose in sync with our hopes.
The scream of 5,500 rpm was ringing in our ears as the throttle blades closed and the Menace calmed to an idle. The shop clock ticked away as we awaited the final results to come in for the first run of MMM… We Did It! As you can see by the dyno chart, we scored 432 hp at 5100 rpm and almost 505 ft-lb of torque at 3,800 rpm. The menace is officially a monster, how could we not be pleased. We started generating 400+ hp at 4,200 RPM and the freight train didn’t stop pulling until after our 5,500-rpm shutdown. Our only cleveite was not being able to power though to 6,500 rpm, perhaps with a roller cam and studier valve springs. Nevertheless, we are plenty pleased with these results. Now I wonder what a healthy shot of nitrous would do?
As you can see, we have a decent power curve with a respectable 432 hp. Don’t worry, we’re not done yet.