Easy as 1, 2, 3: BBC Stroker Upgrades

The right heads and cam can literally transform your BBC!

The right heads and cam can literally transform your BBC!

Big-block Chevy owners share a common goal with all enthusiasts. That goal is a simple one – make more power? As luck would have it, the answer to that question is quite simple.

There are endless ways to improve the power output of almost any internal combustion engine, including the 540-stroker used for this dyno session. When you go looking to improve the power output, one of the first things that comes to mind is forced induction. True enough, adding a turbo or supercharger to even your otherwise stock motor will result in a significant power gain.

We know, we did this to the Power Adder crate motor from BluePrint Engines with great success. The same can be said for a small (or even large) dose of nitrous oxide. Adding juice to your motor can literally transform it from mundane to maniacal, depending on the amount supplied.

The final avenue is likely the most popular, often labeled the bolt-on, or all-motor route. This involves replacing, or otherwise improving, the existing engine components to improve the breathing potential or efficiency. Things like ported heads, cams, and free-flowing induction systems fall into this category.

While the other methods certainly have their merits, we chose the all-motor route for improving the power output of this 540c.i. BBC crate motor. We previously ran the BPE BBC Power-Adder crate motor with nitrous, a pair of superchargers (actually three) and turbos, but this time we opted to improve the normally aspirated power. Naturally, you can later combine these all-motor improvements with forced induction and/or nitrous oxide for a more serious effort, but let’s take things one step at a time and add power by improving what we refer to as the “Big Three”.

We replaced the milder blower cam with a healthy, solid-roller cam that offered a .748/.714 lift split, a 276/284-degree duration split and 110-degree lsa.

We replaced the milder blower cam with a healthy, solid-roller cam that offered a .748/.714 lift split, a 276/284-degree duration split and 110-degree lsa.

In terms of a performance engine, the “Big Three” refers to the top end of the motor, namely the heads, cam, and intake manifold. The reason for the “Big Three” label is that these major components all but dictate not only the power output of the motor, but also the overall power curve.

Of course the short block must be up to snuff to accept the significant change in power. There are other components that can be employed to fine tune the power output, but the major players are still the heads, cam, and intake.

The test motor was already a healthy unit. Supplied as a crate long block, the BPE 540 was designed for use with power adders and built accordingly. Starting with their own HD, 4-bolt block, the BPE 540 was treated to forged internals, including a 4.25-inch stroker crank and, 4.50-bore, forged pistons swinging on forged, H-beam rods.

The short block also featured a dedicated blower cam, though it ran equally well with nitrous and a pair of turbos. The solid-roller profile offered .652 lift, a 255/262-degree duration split and 114-degree lsa.  Naturally the big block also received solid-roller lifters, hardened pushrods, and a complete oiling system.

Topping the stout short block was a set of as-cast, aluminum rec-port heads. For dyno use, we added an Edelbrock 454-R intake, 950 XP Holley, and MSD billet distributor. Know that we made over 1,300 hp with the turbos using this basic combination, so it was no slouch as supplied by BPE. Run in normally aspirated trim, the low-compression 540 produced 648 hp at 6,000 rpm and 629 lb-ft of torque at 4,500 rpm.

The combination worked amazingly well under boost, but we couldn’t help but wonder if there was more power just waiting to be unleashed from the normally aspirated combination?  With power on our mind, naturally we looked to replacing the Big Three.

Off came the BPE, as-cast aluminum heads to make way for the AFR head swap. The heads were installed with Fel Pro MLS head gaskets and ARP head bolts (both heads used the same head bolt combination).

Off came the BPE, as-cast aluminum heads to make way for the AFR head swap. The heads were installed with Fel Pro MLS head gaskets and ARP head bolts (both heads used the same head bolt combination).

Starting with the cylinder heads, the aluminum, as-cast, rec-port heads from BPE were replaced by a set of CNC-ported, AFR 377 Heads. Actually overkill for this application, these AFR heads were actually destined for a larger 565 build up using a World Product block, but since we had them available, we decided to test the big-three upgrade on this 540.

The AFR heads featured 377cc intake ports that flowed over 435 cfm, albeit at .900 lift. Hardly high-lift wonders, the 377 AFRs flowed 415 cfm at just .600 lift, meaning there was plenty of flow to feed the 540. Run on a wilder BBC combination, these AFR heads could support over 875 hp, but we would get nowhere near that number on this low-compression application. The AFR 377 heads also featured a 2.30/1.88 valve combo, a solid-roller spring package and CNC-profiled, 121cc combustion chambers.

To add a touch more lift, we installed a set of Crane, BBF 1.73-ratio aluminum roller rockers. AFR supplied a set of adjustable guide plates to help us individually line up each rocker.

To add a touch more lift, we installed a set of Crane, BBF 1.73-ratio aluminum roller rockers. AFR supplied a set of adjustable guide plates to help us individually line up each rocker.

To take advantage of the airflow offered by the AFR cylinder heads, the 540 needed wilder cam timing. Though a solid roller, the BPE blower cam was replaced by a much more aggressive unit from the COMP Cams catalog. The Super Gas grind (pt#11-734-9) featured a .748/.714 lift split (with 1.7 rockers), a 276/284-degree duration split and 110-degree lsa. This represented a significant step up in cam timing from the original blower cam.

The cam was combined with the solid-roller lifters supplied with the crate motor, but the new heads required different (hardened) pushrod lengths and replacing the double-roller timing chain. The blower cam was designed for use in a Gen VI block (the BPE featured a Gen VI cam-retaining plate). The new cam was designed for the earlier Mark IV BBC (with no cam retaining plate). The cure was to use a new Mark IV timing chain combined with a cam button to properly locate the cam. The final touch was a set of 1.73-ratio (BBF) aluminum roller rockers, bringing the final (pre-lash) lift figures to .761/.727.

The final modification to our 540-stroker was the induction system. Though the Edelbrock 454-R intake and 950 HP Holley were well-suited to the milder 540, we wanted to step things up on the new combo. To that end, we gathered together an Edelbrock Super Victor and Holley 1,050 Ultra Dominator. Any self-respecting big block should be sporting a Dominator, but if you decide on one, make sure to step up to the Ultra series (worth it on weight savings alone).

We retained the MSD billet distributor and plug wires, along with the dyno headers, but did cover the AFR 377 heads with the supplied cast-aluminum (AFR logo) valve covers. Our motto has always been if you got it flaunt it! Given the previous use with power adders, our big-block was well seasoned and ready for action.

BPE 540-Effect of AFR Head/COMP Cam Upgrade  As you can see from the results, the AFR 377 heads and COMP (drag-race) roller cam offered some sizable power gains. The power output of the low-compression, power-adder 540 from BPE increased from 648 hp and 629 lb-ft of torque to 734 hp and 633 lb-ft of torque. As is evident, the free-flowing AFR heads and wilder cam timing pushed power production higher in the rev range, with the horsepower peak coming 800 rpm higher and the torque peak coming 1,000 rpm higher.

BPE 540-Effect of AFR Head/COMP Cam Upgrade
As you can see from the results, the AFR 377 heads and COMP (drag-race) roller cam offered some sizable power gains. The power output of the low-compression, power-adder 540 from BPE increased from 648 hp and 629 lb-ft of torque to 734 hp and 633 lb-ft of torque. As is evident, the free-flowing AFR heads and wilder cam timing pushed power production higher in the rev range, with the horsepower peak coming 800 rpm higher and the torque peak coming 1,000 rpm higher.

After dialing in the tune with one jet change, we were eventually rewarded with peak numbers of 734 hp at 6,800 rpm and 633 lb-ft of torque at 5,500 rpm. As expected, the wilder cam timing and free-flowing heads shifted the power higher in the rev range, but the losses below 4,000 rpm were more than offset by the gains up top. Now sporting an extra 86 hp, this stroker is just begging for more boost.

Sources: AFR; airflowresearch.com, ARP; arp-bolts.com, BluePrint Engines; www.blueprintengines.com, COMP Cams; www.compcams.com, Edelbrock; www.edelbrock.com ,Holley/Hooker/NOS; www.holley.com, MSD; http://www.msdperformance.com, Westech; http://www.westechperformance.com

About the author

Elizabeth Puckett

Elizabeth is a seasoned writer and hardcore gearhead. She was born with motor oil in her blood and a passion for everything that goes fast.
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