Our flat-top KB pistons were equipped with a Sealed Power moly ring set. Care during pisto
Based on both cost and performance, Blueprint chose 200cc Dart Platinum Pro 1 heads. For this base engine, these are used in as-cast form. The wet flow of these heads proved to be capable of generating a substantial amount of extra torque and hp over the original Pro 1. With modern fine-casting techniques, as-cast heads are a country mile ahead of heads produced 15 years ago. With forms closely replicating ported heads, they flow substantial amounts of air (see chart). These heads are available in straight or angled plug, and with 72cc or 64cc chambers. We used the 72cc angle plug heads (Part No. 11411111P). This combination of parts and block decking gave our Blueprint engine a 10.25:1 compression ratio.
Cam & Valvetrain
If the heads are ineffectual, nothing else matters if power is the intent. Nevertheless, if good heads are to be used, the responsibility toward making power then falls squarely on the cam and valvetrain. Make any kind of judgmental error, and the prospect of optimal output just flies out of the window. The guys at Blueprint had a good idea of what was needed for their 383 stroker, so they used this round of testing to get the cam spec right for the Dart Platinum Pro 1 heads. Certain characteristics were known to be needed. This included a higher valve lift than for a 350, as well as a tighter LCA. Also, all this had to be tied in with fast opening and closing, so a fairly aggressive profile was needed to allow for ample cylinder filling. The problem is that aggressive cams tend to wear fast, and the absence of ZDDP in the new oils exaggerates this. A major part of the fix is the use of COMP's flat-tappet cam nitride hardening service. For $110 over the cost of the cam, you can have the cam case hardened to produce a low-friction, super wear-resistant surface. Anything that helps reliability in this department is worthwhile. With a compatible quality material lifter, nitriding has shown to deliver long life, even with an aggressive cam.
So how aggressive a cam are we talking? Using catalog profiles, Blueprint chose a custom grind. This cam has a COMP No. 5444 profile on the intake, and a 5445 on the exhaust. These gave seat and 50 thousandths lift durations of 270/226 and 274/230 respectively, and with a 1.65:1 COMP rocker on the intake and a 1.6 on the exhaust, valve lift was .530 and .520. The lobes were ground on a 106-degree lobe centerline angle at four degrees advance. From the short duration figures, it can be appreciated that the cam is more what you would expect in a truck motor than a race motor. This point is being made so that you understand this is no race motor thinly disguised as a street unit; you really could put this engine in your truck, load it up, and drive it.
Our motor's oil pan was a stock pattern unit with a tough plastic enamel finish that resis
A couple of points to note here regarding the cam duration and lift: First, the intake-to-exhaust-duration split. It is more usual to have the exhaust 6-8 degrees longer than the intake, and though this is good for top end, it does cause a drop in cruise mileage. Note the cam spec has only four degrees more exhaust duration for better street mileage. It's a small but relevant point demonstrating that Blueprint is making a real effort to get mileage as well as performance. Also note the use of a 1.6:1 rocker instead of the more common 1.5:1 on the exhaust. Although not necessarily the case with bigger cams, Blueprint's testing has shown that with the Dart heads and a shorter-than-usual cam, exhaust duration with the 1.6s paid off.
Induction & Ignition
To run in PTRA Performance Street, a non-air-gap intake from any one of four different manufacturers is mandated, as is a totally unmodified 750 Holley. After dyno testing showed a very minimal difference between all the candidates, an Edelbrock Performer (part No. 7101) intake was chosen. As for the carb, Blueprint had their carb supplier build a spec Holley 750 for an additional $55 to the cost of the standard build. For ignition, a custom distributor with vacuum advance was built for Blueprint Engines by Performance Distributors. The relevance of this is that it is a mileage distributor. Many hot rodders are still running non-vacuum advance distributors on the street, and it's costing mileage. With an appropriate vacuum can, the Performance Distributor's unit can be worth as much as 2-3 extra mpg.
Dyno TimeTo fit within the regulations for Performance Street, we had to downgrade this engine's normal spec. It's now time to see how it fares on the dyno in the form that we'll run it in the car. The nearby power curves show the results.
The 490 lb-ft of torque from a 10.25:1 motor looks really impressive, especially with the curve carrying down well to the low end. For what is essentially a street motor with mileage in mind, the 453 hp seen was also very good, but would this be enough to cut the mustard against engines purportedly pumping out 490 hp?
The 200cc port Dart Platinum Pro 1's looked to be ideal for our application. The intake va
The lead shot of the completed engine shows it as received from Blueprint Engines, but with our March beltdrive system and ancillaries added. We did this so you can see what a good-looker a regular street unit can be; however, the plan here was to run the engine with an electric water pump, and less alternator and power steering.
A few words about the car are called for to set the scene. This chassis had been used as a bracket car, with a high-rpm 350 for power. It had a Powerglide two-speed with a converter that stalled about 4,400, and a rearend ratio of 5.13:1. Our first reaction was that this wouldn't be ideal, but the first race was only days away, so that's what we had to run.
The installation was finished three days before the first race, just in time for a test and tune session at Shadyside Dragway near Shelby, North Carolina. To be competitive, it was estimated we had to run a 7.3 at 92 mph in the eighth-mile. On our eighth-mile to quarter-mile conversion chart, that equals an 11.26 at between 113 and115 mph. Our first test day recorded nearly record high temperatures. In spite of that, we rolled off the trailer with a 7.36 at 91.92 mph. This was even more encouraging than the numbers might suggest. As suspected, the stall speed on the converter was too high, and the gearing too low: Our Blueprint Engine power plant was turning better than 6,600 rpm in the lights, and peak power was only 5,250 rpm. Also, the engine was breathing hot underhood air, and the suspension travel on the front was topping out and tending to unhook the tires, as indicated by a 1.58-second 60-foot time. If we had the suspension just right, even with leaf springs and the series spec tire, this car should crack the 1.5-second mark for the 60 foot.
Because they work well and come in at a very friendly price, Blueprint uses Dart Platinum
So on that night, we took the car home knowing we could go faster. Since race day was 36 hours away, we knew that there was insufficient time to install a cold air system to the carb, or to get a more appropriate converter and rearend set, but we could make adjustments to the front suspension, so that is all we did the morning before the race. With the weather a little more normal, we expected to turn times a little better than our test. That proved to be the case. Our suspension adjustment looked like a move in the right direction, as we cut a sub-1.5 second for the 60-foot. As for the rest of the numbers, our Blueprint motor powered our 3,100-pound car to a 7.19 at 93.5 mph. That, my friends, was good enough for us to make it through to the final round, where we lost to a car with a real race engine that cost way more than our crate motor.
The real fun part of the day was when the race announcer informed the crowd that our car had a street-spec Blueprint crate motor with a 30,000-mile warranty! We sure had a bunch of folks check us out in the pits after our runner-up performance. There were also a couple of drivers we put away that had a hard time accepting they'd been beaten by a crate motor. The BS stops when the green flag drops!
So with what is essentially a moderate budget motor, we have already achieved a good measure of success. Where from here? The general consensus is that a 7-oh at 95 mph is within reach. We're now looking to test a 4.86 rearend and a converter with 400 rpm less stall for our torque-laden 383. Add to that a cold-air intake, and we can reasonably expect to see our target numbers, but we'll update you on that down the road. Meanwhile, if you're in the market for a hi-po street motor with better mileage than most, check out Blueprint Engines.
ARP head bolts hold the Dart heads down on Fel-Pro head gaskets.
Rocker ratio selection for our Blueprint 383 proved important. Going to a 1.6:1 ratio on t
Normally a Blueprint crate motor such as ours would be equipped with an air-gap-style two-
Carburetion for the PTRA Performance Street class calls for the most basic of carburetion:
The ignition on these Blueprint engines is a Performance Distributors HEI. It's curved for
As shipped, a dressed Blueprint motor comes with an aluminum water pump. We dressed out th
Here's our engine finished and equipped with the March belt-drive setup. Less the March sy
Here is our motor on the DTS dyno, and the power curve over approximately the range we'll
Our donor car belongs to Jack Brown, and is a '79 Camaro ex-bracket racer with a 'glide an
When the final round of eliminations arrived, Jack was still standing, and got the car to