With all of the aftermarket engine parts that have been released over the past few years, HPP has been flush with announcements, overviews, buildups, and tests featuring many of the these new goodies. But for this excursion into Pontiac power, we are taking a more traditional direction.
Those of you who are familiar with Jim Taylor Engine Service know that Jim enjoys building street and race powerplants that use as much of what the factory gave us as possible, and the choice of components for this race engine reflects that sentiment. Here it's the combination of the parts that are key in both making power and maintaining durability.
To that end, Taylor gathered some special factory pieces like a four-bolt main '70 455 block because "the '70 blocks seem to have less core shift than later blocks," he says. Next up was a 428 nodular-iron crank with its 4.00-inch stroke and a set of rare Ram Air-IV heads.
Why a 428 crank in a 455 block? According to Taylor there are a few reasons. "The rod/stroke ratio is better, but there is more to it than that. The loading is different with the 4.00-inch stroke of the 428 versus the 455's 4.210-inch stroke because of the crank's offset--meaning the connecting rod journal is closer to the centerline of the crank. As a result, the engine revs more quickly, seems to be easier on bearings, and just is more efficient. You do get more torque with the 455, but it's not enough of a difference to offset the 428 crank's advantages, especially in a light drag car."
Another aspect to the combination is a longer-than-stock connecting rod that Jim says simply makes for a more favorable rod-stroke ratio that ultimately results in more power.
The Ram Air-IV heads can be worked to flow 300 cfm, and Jim says that 300-306 cfm is what he considers to be safe. "At this level, the customer won't have to worry about water in the ports or other failures," he said. Taylor also related that at 300 cfm and with 320-fps velocity, 440 engines have the potential to produce up to 720 horses.
For the intake ports, Jim described the porting procedure thusly, "The roof is lifted to straighten the port as much as possible, and the cross-sectional area at the pushrod bulge is unified. The port floor is lifted with epoxy about the same amount as the roof was lifted. In the valve pocket, the bowl area is made as concentric as possible. Then the short-turn radius is widened and contoured with a specific radius."
"On the exhaust side, the short-turn radius is widened, and the bowl under the valve seat is enlarged but not bigger than the valve seat area--and that's about it."
However, Taylor warned that the 300-cfm intake flow must be maintained through the intake tract and equalized. To that end, the Victor Dominator intake received a Dittmer turtle and was welded and then ported. "Any unmodified cast manifold, when attached to the head, will have a different affect on each port it feeds. The objective is to have all of the intake valves see the same volume at the same velocity each time the valve opens. This is known as flow balancing. Flow balance and flow charge are major contributors to high-horsepower-to-cubic-inch ratios," Jim shared.
With the intake manifold on the head, flow is 303 cfm and with a header on the head, exhaust flow is 215 cfm. This results in a 70-percent exhaust-to-intake flow ratio. Though 75 to 80 percent has been accepted as optimum over the years, Taylor has found that his engines can make just as much power at this level.
There are plenty more aspects and parts to discuss, but the rest is best done in the captions. All totaled, this combination is worth 659 horsepower and over 600 lb-ft of torque on the dyno. Since Pontiac blocks have been known to split up the middle over 700 hp, at 659 there is a durability cushion built in, and there are bragging rights for getting there with a factory-issue block/crank/head combo.
Taylor builds this combination for a multitude of racers. Since the first engine that we dyno'd was already close to completion when we first saw it, some of the photos here are from a twin that is currently going together, but the recipe is the same. Obviously, this will not be a nut-and-bolt buildup story, but rather a discussion of the more interesting aspects of the engine with dyno results to back-up Taylor's build philosophy.
Here the 440 engine is bolted up to the Hoffman Stuska dyno at Bitner Automotive.
This is the '70 455 four-bolt block that was the basis for the engine. The billet steel ma
Taylor says that the nodular iron cranks are more durable than ductile cast iron and the c
For this project, the crank was lightened to reduce mass for balancing since lighter after
Jim went with SRP forged aluminum pistons with full-floating pins and Howard's forged stee
A set of C&A zero gap rings were employed to increase the efficiency of the combustion pro
Here we can see that the block has been grooved around the cylinder bores to accept O-ring
The trick Moroso eight-quart oil pan not only holds more crude for the engine, but it also
A Crane 8620 billet solid roller cam, ground to TFX specs, is the brain of the operation w
Taylor was able to get his hands on a blueprint for the Ram Air-IV head. With it, he disco
Here we see quite a difference in the size of a stock D-port intake port and the modified
The stock R/A-IV chamber shown here features 66cc volume. Though not shown, the race heads
Ferrea stainless one-piece valves are 5.200 inches long to fit the R/A IV heads with the f
Here Mark Erney lowers a Ram Air-IV head onto the block over the ARP studs. A Clark copper
Here you can see the Comp Cams valve springs and the Crower 1.65 roller rockers. Also note
The carb is an out-of-the-box Holley HP 1050 Dominator, but the Edelbrock Victor Dominator
The distributor is an original Pontiac piece with a bronze gear installed and an MSD Cap-A
Here is the nearly completed engine. You can also get a good look at the crank trigger.
These are the custom headers that were welded up by Mark Erney and used in the dyno testin
In the dyno room, the engine was warmed up to get the oil and water to the proper temperat
Shop owner and dyno master Fred Bitner adjusts the air intake over the carb between pulls.
Here's command central for the dyno. We pried Fred's hands off of it for a second by telli
The dyno cell is cramped and usually quite warm after a pull. Regardless, Taylor (left) Ma
THE BEST DYNO PULL
After adjusting jetting and timing and making six pulls through the course of the day, the best pulls was achieved with #96 jets in the Holley and 35-degrees total timing, which is what the engine started with (for example, a pull with 37-degree timing and #94 jets dropped horsepower by 10 because of a lean condition). Notice that the pull began past the torque peak. This is because the dyno brake couldn't hold the engine at a lower rpm.
|RPM ||Horsepower ||Torque |
|4,800 ||554.7 ||604.6 |
|4,900 ||559.9 ||599.8 |
|5,000 ||568.9 ||596.8 |
|5,100 ||576.0 ||592.8 |
|5,200 ||584.7 ||590.1 |
|5,300 ||593.8 ||587.2 |
|5,400 ||602.2 ||585.5 |
|5,500 ||610.7 ||581.7 |
|5,600 ||617.3 ||577.9 |
|5,700 ||624.2 ||573.7 |
|5,800 ||629.5 ||568.0 |
|5,900 ||634.6 ||563.9 |
|6,000 ||639.2 ||558.6 |
|6,100 ||645.0 ||555.4 |
|6,200 ||650.5 ||550.3 |
|6,300 ||654.5 ||544.4 |
|6,400 ||657.2 ||538.6 |
|6,500 ||659.4 ||532.5 |
|6,600 ||658.3 ||523.4 |
|6,700 ||657.5 ||515.4 |
|6,800 ||655.7 ||506.0 |
|6,900 ||653.0 ||496.8 |
|HIGH PERFORMANCE PONTIAC ENGINE BUILDUP WORKSHEET |
|Engine Displacement: 440 ci |
|Horsepower: 659 |
|Torque: 604 lb-ft |
|Bore/Stroke: 4.188"/4.00" |
|Block/Crank combo: 455/428 |
|Bore/Stroke ratio: 1.047" |
|Rod/Stroke ratio: 1.675" |
|BOTTOM END |
|Block description: ||1970 455 XF code |
|Preparation: ||Degrease, magnaflux, install four Nunzi four-bolt main caps, mill to even the decks, fill with hard block with torque plate, tap lifter feeds for screw-in restrictors, bore and hone with torque plate, tap lifter gallery ends for 3/8" NPT plugs, O-ring deck for copper head gasket |
|Deck Height: ||10.200" |
|Crank: ||1969 428, nodular iron, standard journals |
|Preparation: ||Cut mains .010", cut rod journals .050" for Howard's rods 2.200" big end, adjust index (degrees apart of the rod journals), adjust stroke to 4.00" at all journals, radius oil holes, polish |
|Balancer: ||BHJ, Elastomer, 6.8" diameter, PN PO-IB-7 |
|Rods: ||Howard's forged steel |
|Rod length: ||6.700" |
|Preparation: ||Install Crower .990 bushings, measure bearing end diameter at torque spec, check all dimensions, wash |
|Bearings: ||Mains-Federal Mogul 151 M10 HD, rods-Federal Mogul B.B. Chevy HD PN 87200CH STD |
|Preparation: ||Verify size, check locking tang for fit in rods, wash |
|Pistons: ||SRP forged, full floating pin, 1/16", 1/16", 3/16" ring grooves |
|Preparation: ||Measure, check pin fit, measure ring grooves for width and depth |
|Piston to deck height: ||.008" |
|Piston Pins: ||SRP floating with spiral locks |
|Rings: ||C&A ZG with light tension oil ring, Moly top ring, ductile iron zero gap second ring |
|Preparation: ||Measure width, inspect, file to fit |
|Rod bolts/head studs/main studs: ||ARP |
|OILING SYSTEM |
|Windage tray brand: ||Original Pontiac modified |
|Crank scraper: ||Custom-made at Jim Taylor Engine Service |
|Oil pan: ||Moroso 8-quart |
|Oil pump: ||Sealed Power 60lb, Nunzi's pump drive |
|Preparation: ||Disassemble, inspect, wash |
|Casting number: ||614 Service Replacement R/A-IV |
|Chamber Open/closed: ||Open |
|Head mods: ||Porting on intake and exhaust, bronze guides, receiver grooves for O-rings |
|Combustion chamber volume: ||66 cc |
|Flow at 28 inches of water: |
|Intake: ||300 cfm at .700 lift |
|Exhaust: ||205 cfm at .700 lift |
|Compression Ratio: ||12:1 |
|Valves: ||2.11" Ferrea 6000 series int./1.77" 6000 series exhaust |
|Retainers: ||Comp Cams Titanium |
|Keepers: ||Comp Cams 10 with lash cap |
|Valve guides: ||Bronze |
|Rocker studs: ||ARP, Pontiac guide plates, Nunzi's rocker stud girdle |
|Rocker arms: ||Crower 1.65:1 roller |
|Pushrods: ||Smith Brothers |
|Diameter: ||5/16" |
|Length: ||9.150" |
|Brand: ||Crane 8620 billet solid roller with TFX grind |
|Duration at .050: ||272/278 |
|Lift: ||.420/.420 lobe, .670/.670 net at the valve |
|Centerline: ||110 |
|Lobe Separation angle: ||112 |
|Installed position: ||110 |
|Lifters: ||Crower roller |
|Valve springs: ||Comp Cams #999 triple |
|Seat pressure: ||200 lbs |
|Open pressure: ||600 lbs |
|Timing chain: ||Rollmaster double sprocket |
|Carb: ||Holley HP |
|Size cfm: ||1050 |
|Jets Primary: ||#96 |
|Secondary: ||#96 |
|Fuel pump: ||Dyno set up |
|Capacity: ||300 gph |
|Fuel line size: ||Dyno set up 3/8" |
|Intake manifold: ||Edelbrock Victor Dominator, single-plane |
|Mods: ||Welded and ported |
|Distributor: ||Factory Pontiac with Bronze gear and MSD Crank Trigger system |
|Amplifier: ||MSD 7AL |