We used a set of 1 5/8-inch...
We used a set of 1 5/8-inch dyno headers, which are drilled for exhaust gas temperature probes (EGTs)-a valuable source of info when tuning.
Having heard good things about the 380hp crate and seen them in action, we were interested in tossing one on the dyno and examining the output characteristics for ourselves. We contacted a local Mopar Performance dealer, Glendora Dodge, to see if they had any crate engines lying around wanting to kick up some dust. It just so happened they were holding one for customer delivery. We asked them to contact the customer and propose a dyno evaluation and tune of the crate, on our dime. Turns out, the customer, Tom Mociler, had some time before his '68 Dart project was ready for the new powerplant. With the blessing of Mopar Performance's big cheese, David Hakim (regarding Tom's warranty concerns), we were on.
We dutifully loaded the big blue box and headed out to our favored haunt for such hijinx, Westech Performance Group, for a run on the SuperFlow dyno. Mopar Performance claims 380-plus horsepower from this crate-not too far off the magic 400 number-so the usual pre-test jaw boning and haggling began. Just how much was in it? The engine's owner, Tom, had supplied a new 750 Mighty Demon carb, which we figured would have a favorable influence on output. He also supplied a case of Mobil 1 synthetic lube for a post break-in oil change, which is usually worth a couple of odd ponies. We had all day to run our tuning loops, with no real parts changing planned, so we'd have the luxury of time to tune it to a razor's edge. We prelubed the engine, stabbed the distributor, bolted on a set of 1 5/8-inch dyno headers feeding into a pair of 3-inch Flowmaster mufflers, hit the ignition, and the crate fired immediately. We dialed the timing to 34 degrees total for a baseline setting.
A complete MP electronic ignition...
A complete MP electronic ignition is supplied with the crate, including the control unit, ballast, and wiring. We installed the distributor and hooked it to the dyno's MSD Digital 7 box.
Dyno operator Steve Brule set the machinery to run through an automated break-in cycle, and the engine sounded sweet. It idled down easily to a steady 850 rpm, although the long-duration cam made its presence known with about 6.5 to 7 inches of vacuum. Left alone to monitor the dyno console, I goosed the throttle and found that the 360 responded sharply. Anticipation started to take hold, and we had to sneak a peek. Then, we set the load dial to 3,800 rpm and gave the control handle a tug. The raw torque counter shot up to the 375 ft-lb range, and it was obvious this thing was going to have some oats! Mr. Brule returned to the controls, and we ran a few static pulls to confirm that the fuel mixture was in the zone. It showed to be in a safe range with the box-stock Demon settings.
Showtime! We were ready for the first real pull. The controls were set for a short pull from 3,500-5,100 rpm, and we had our first numbers: 421.9 ft-lbs at 4,200 rpm, 377 hp at 5,100, and still climbing at the top of the pull. We had no doubt it would find the rated 380 number, and more.
The numbers from the dyno's readout indicated we were a little lean. We next went through a jetting loop, running several pulls and finding best power under the test conditions, stepping up to 78 primary and 87 secondary jets from the Demon's stock jetting of 75/84. With the jetting dialed in, still at 34 degrees of timing, the engine handily exceeded the rated output with 432.4 ft-lb at 4,100 rpm and 394 hp at 5,300 rpm. We were knocking on 400 hp and moved on to the timing loop. It didn't take long to find the optimal timing to be 36 degrees total, and we now cracked over the magic numbers-401 hp at 5,400 rpm and 437.7 ft-lb at 4,100 rpm. With that, we were fairly satisfied and confirmed the jetting through a second fuel-tuning loop, finding that the same 78/87 combo that worked with 34 degrees was still on the money with the timing change.
To top the intake, a Mighty...
To top the intake, a Mighty Demon 750 mechanical secondary carb was used-a good choice for the 380-horse crate 360. The Mighty Demon has many of the same features as a Race Demon, including a radiused air entry and replaceable air bleeds. The fuel-delivery curve was fine, needing only minor jetting to get it right on target, and in this application, it didn't need additional trimming of the fuel curve with the air bleeds.
We began with the timing set...
We began with the timing set at 34 degrees total advance. Right off the bat the crate delivered 377 hp and was still on its way up at the end of a 5,100 rpm pull.
Demon carbs come with large...
Demon carbs come with large glass windows in the float bowls, which makes setting the float levels quick, easy, and accurate. Set to have the fuel in the middle of the window.
We spent half-dozen pulls...
We spent half-dozen pulls dialing in the carb mixture with jet changes until we had the optimal combination of 78/87. Carb calibrations alone had the power cranked up to a healthy 394 hp. The 400 hp pull was so close we could taste it. Looking for more, we began twisting the distributor and found that 36 degrees was clearly the best, and it was enough to crack the 400 hp barrier with 401 measured ponies.
With the engine broken-in...
With the engine broken-in to our satisfaction, the original oil was dumped to make way for a new filter and some fresh slick stuff. We had some Mobil 1 synthetic on hand, which is usually worth more power through reduced friction. Keeping with tradition, the original filter was cut open, and with no wayward shrapnel to be seen, we were good to go. Eventually, power was up to 409 hp.
An open and a four-hole spacer...
An open and a four-hole spacer were tried. No noticeable improvements were gained. With this engine combo, bolting a spacer does not enhance the MP manifold.