We've finally reached a point with our Diplomat police car where we canuse a couple hundred more horsepower. Instead of diving into the innersanctum of the 318 now residing between its framerails, we opted tostick a slightly used 360 we had laying around into the interceptor. The360 is from another project car of ours and features a 10:1 compressionratio, an otherwise stock bottom end, a fairly aggressive hydraulicflat-tappet cam, and a pair of mid-'70s 360 smog castings outfitted with2.02 intake valves. Equipped with an Edelbrock Performer RPM Air Gapintake manifold and a 750-cfm Demon carburetor, this little gem knockedout 418 horses and 443 lb-ft of torque on a conservative (stingy wouldbe a better word, actually) dyno. The engine is stout enough to powerour '68 Barracuda project car into the high 11s at 114 mph. So it'sdefinitely up to the task at hand. But we made a couple of changes tothe 360 to make it more compatible with the girth of the '89 M-Body. Thecam would have to go, as it didn't pull enough vacuum at idle to run thepower accessories, and believe us when we say a 3,800-pound vehicleneeds a lot of braking power to haul down from extra-legal speeds. inits place went a mild Crane hydraulic to boost low-rpm torqueproduction. Also, all of the accessories including the intake with Q-Jetcarb would be swapped over to the new engine, as well as the restrictiveexhaust system. Baring any complications with lean-burn compatibility,the Q-jet would remain. The Dippy would then be chassis dyno tested withthe old system and then retested with the new high-flow system todemonstrate the benefits of a good high-performance exhaust system.

Lean-Burn Sucks

No mincing of words necessary. With the hi-po 360 installed between thefenderwells, the lean-burn system wouldn't run right to save its life.Timing changes just didn't seem to make any difference in the way itran. In fact, the car felt outright flat in the power department. Thedecision was made to address the ignition first. so we called ourbuddies at Glendora Dodge for a Mopar Performance electronic-ignitionsystem that comes complete with an orange ECU, a vacuum-advanceelectronic distributor, and a wiring harness to tie it all together.Next on the chopping block was the carburetor. We were never quite atease with the feed-back Quadrajet perched on the Diplomat's intakemanifold, and it ran poorly enough to give us an excuse to try the800-cfm Competition Thermoquad that's been taking up space in ourgarage. Plus, the TQ just looks right.

Engine Specs

Displacement: 365 ci

Compression Ratio: 10:1

Pistons: Federal-Mogul TK hypereutectic pistons

Cam specs: 216/228-degrees duration at .050-inch valve lift,.484/.512-inch lift with Crane 1.6:1 ratio rocker arms (.454/.480 with1.5:1 rocker ratio), 112 -degree LSA

Cylinder heads: Aerohead reconditioned "578" castings with2.02/1.60 valves

Induction: Factory cast-iron spread bore with 800-cfm CarterThermoquad carburetor

Exhaust: Factory exhaust manifolds, 3 catalytic converters,single 2-inch exhaust