Ready to romp, we headed to...
Ready to romp, we headed to Westech and loaded our engine on their dyno to see what 408 cubes of tunnel-rammed, W-2-headed Mopar were worth. Though the Crane roller inside was the smallest listed in their catalog, we'd have no problem opening the valves to create enough power by supplementing it with Crane's 1.6 rockers.
It was with much anticipation that we loaded our 408-stroker small-block for the trip out to the Westech dyno facility. We already knew it had to be a serious combo, even though we changed one specification and dialed the compression back from our original plan of 11.7:1 to a pump-gas friendly 10.4:1 (see sidebar: Compression Quandary). The lower compression specification would certainly lower output, estimated at about 5.5 percent, but we'd have the opportunity to jack it up to race-gas territory later. With the scienced-out heads, plenty of cam on board, and serious induction up top, there was little doubt that our big-inch small-block would deliver.
Finishing It Off
We had a few details to add to our stroker mill before we had a real ready-to-run stroker. A trip to Bob Mazzolini Racing in Riverside, California, netted us a Mopar Performance aluminum bronze-geared distributor drive (#P3690874)-required for compatibility with our steel roller cam. An MSD billet distributor was popped into the hole at the back of the block, and wired to the plugs with MSD wires. The Westech dyno has an MSD Digital 7 ignition, which plugs right into our distributor setup. In an outrageous display of cheapness, we spun the 89-cent Autolite plugs out of our last dyno small-block, and screwed them into our stroker's fresh W-2s.
Last month we bolted on a pair of Speed Demon four barrels to set up the Enderlie linkage kit for our MP tunnel ram. We initially had a set of 750 annular race Demons in mind, but found that Demon makes a pair of down-leg booster 750s specifically for tunnel-ram applications. We decided to go with the carbs Demon has already developed for the job, picking up a pair of Race Demon 750TRs. Since these carbs are factory-calibrated for tunnel ram dual-quad applications, we figured they would save us precious dyno time in dialing up a proper fuel curve.
Our last missing components were the headers. We heard that TTI was busy developing 1 7/8-inch headers for both the W-2 and W-5 heads. Good-fitting streetable headers for Mopar Race heads? It sounded too good to be true. Sam Davis and the crew at tti had the jigs complete and just received the bending dies as we were loading our truck for the dyno test. As we mounted the 408 to the SuperFlow dyno, we sent our buddy "The Rooster" to pick up the first set of W-2 headers out of the tti shop. The headers were still hot from welding when he loaded them up.
On the Dyno
With the headers bolted up (they fit like a glove), the 408 was ready for action. True to our pump gas plan, the dyno's fuel system was filled with plain 91 octane Unocal unleaded. We made a few partial pulls to check the jetting, and followed up by fattening the Demons with a jet change to #80s all the way around. We could already see that the 408 was kicking out power, big time. On our partial pull, we had seen 590 hp at 6,000 rpm, and well on its way up. With the jets changed, we were ready to let it rip, so we set the dyno controls up to 6,700 rpm to reap the horsepower. It wasn't going to happen just yet, as a broken rocker adjuster ended our dyno day.
According to Chase Knight, Cam and Valve Train Components Product Manager at Crane Cams, "For years, we never had any problems with our adjusters, but something happened in the late Summer of 2001. Over a 10-day period, we began getting reports of the adjusters snapping off under the lock. We immediately began analyzing three suspected processes involved in producing this part-carburizing, hardening, and annealing. What we discovered was that all processes were within tolerance, but we narrowed the tolerance anyway. Since then, we have had no problems with the adjusters." Should you have rockers that you suspect, call the Crane Cams technical assistance hot line at (386) 258-6174.
We had the first-ever set...
We had the first-ever set of tti W-2 headers in existence, hot off their new jig. These are real street headers for W-2s, featuring 1 7/8-inch primaries and 3 1/2-inch collectors. Though we got away with it for our dyno test, the engine should have a 90-degree oil filter adapter for filter clearance on the right side.
For carbs, we went with a...
For carbs, we went with a set of Demon 750TRs, which come factory-calibrated for tunnel-ram applications. At 600-plus horses with only minor tuning, we were happy with the results.
Best peak power was found...
Best peak power was found at 38 degrees total timing, and nary a trace of detonation on plain 91 octane Unocal unleaded pump gas.
With tunnel-ram induction,...
With tunnel-ram induction, distributor clearance becomes tight with the larger-than-stock MSD distributor. We had to find a position that would allow it to rotate enough to give the required range of timing adjustability, and then wire up the cap accordingly.
With the morning session on...
With the morning session on a tight schedule, dyno operator Steve "Lightning Lash" Brule had the valves run to Crane's specified .020-inch intake, .022-inch exhaust in no time.
No trick slippery stuff in...
No trick slippery stuff in the crankcase to try to squeeze more power out of our stroker, just a fill of quality Unocal 10W-30 motor oil. Just as Crane had recommended, our oil pressure was normal without requiring the traditional blocking off or sleeving of the lifter oil galleries. This is due to Crane's new roller tappet design; at the .420 lobe lift of our cam, the roller lifters proved to be a "drop-'em-in-'n'-go" deal.