Like everything else in life, our quest for performance requires that we accept the good with the bad. Case in point: building or improving the performance of your small-block Chevy. The good side of the equation is that the small-block has been around since the mid '50s and, as such, has a tremendous following both in terms of enthusiasts and the performance industry. The benefit of the popularity is that there is an abundance of performance hardware available both directly from Chevrolet in the form of their GMPP catalog as well as from the aftermarket. The availability means that we have a great many choices when it comes time to build or upgrade our existing powerplant.
The downside to the abundance of aftermarket availability means that not only do we have enough choices, but often times we have too many. By this we mean that the vast array of different manufacturers and associated components can be nearly overwhelming. Which heads go with which cams and why can't someone go to the trouble of assembling the various accessory components required to duplicate the advertised test results?
Well, fellow enthusiasts, TFS responded with not one, but with a number of different performance packages that are designed to take the guesswork out of building a small-block Chevy. The TFS small-block Chevy engine kits are available in power ranges from mild to wild. In performance terms, the mild-to-wild designation translates into power numbers ranging from 350 hp to over 500.
Not surprisingly, the power range offered by the various TFS kits covers the vast majority of street machine buildups. Sure, we all want to brag about having 600hp small-blocks, but the reality is that short of forced induction, not many street small-blocks can achieve that power level with any kind of streetability. TFS took this fact into account when designing these engine kits, as they offer 18 degree cylinder heads that will produce a great deal more power, but not many daily drivers will require the kind of flow offered by the race heads. For most of us, all we want (or need) is a good set of performance aluminum heads and matching cam to go with a four-barrel carb and dual-plane intake. Such a combination should produce gobs of horsepower and torque combined with thousands and thousands of trouble-free miles.
We wanted to put one of these kits to the test, so we immediately contacted Trick Flow Specialties. The highlight of the supplied engine kit was naturally the TFS 23 degree aluminum cylinder heads. Right off the bat, the aluminum heads offered a performance gain by reducing the curb weight compared to a set of traditional cast-iron heads. Those few enthusiasts who still cling to the notion that cast-iron heads are somehow stronger or in some way superior to aluminum heads should join the rest of us here in reality. Aluminum heads offer nothing but advantages in weight, reduced detonation and repairability compared to the old-tech iron heads, to say nothing of the superior port and chamber designs that greatly improve power potential. Even the very best fuelie, camel-back or turbo heads are no match for a set of off-the-shelf 23 degree TFS aluminum heads. Cylinder head port design has come a long way since the introduction of the small-block, even since the musclecar era. It should come as no surprise that a modern, computer-designed aluminum head can out-perform a set of the early GM performance castings, to say nothing of a set of the more pedestrian stockers.
According to the TFS literature, the requirements for achieving the desired power results from any of its engine kits required only a few simple items. Naturally one of those requirements was a suitable 350 Chevy (or stroker variant) short-block. The other important items included a Holley (or equivalent) performance four-barrel carburetor and a matching four-barrel intake manifold. The size of the carburetor and specific intake manifold depended on your chosen power output. TFS specified a dual-plane Edelbrock Performer intake and a 600-cfm Holley carb for the lower performance 350hp kit, but stepped up the induction system to a 750 Holley double-pumper and a Performer RPM Air Gap or Victor Jr., depending on the exact power level.
In each case, TFS specified a camshaft tailored to work with the cylinder heads and induction system to produce the desired power level. Remember, it is important to tailor the cam timing, induction system and cylinder head flow (and port volume) to work together to produce optimum power. The wrong choice on just one component can literally ruin a perfectly good buildup. This is why matched systems like the engine kit from TFS make so much sense.
For our needs, we chose the Pro Street Engine Kit designed to produce 445 hp and 405 lb-ft of torque (according to the specs supplied by Trick Flow). As indicated, this included the impressive TFS 23 degree performance aluminum heads. According to TFS, the 23 degree small-block heads flowed over 250 cfm on the intake and nearly 190 cfm on the exhaust. These flow figures jump up by 3 to 6 cfm if you opted for the optional CNC combustion chambers, which we did not. These are pretty impressive figures for intake and exhaust ports that measure 195 cc and 75 cc, respectively. Of course, it is possible to greatly improve the flow rate of the heads with additional porting (TFS now offers CNC versions of the 23 degree heads), but we wanted to check out the results of the as-cast heads as delivered by TFS. Check out the supplied airflow data on page 96 for a complete rundown on the flow specs for the TFS aluminum heads.
In addition to the impressive intake and exhaust ports, the TFS aluminum heads also featured 2.02 intake and 1.60 exhaust stainless steel valves, bronze valve guides and Viton valve seals. Our heads were set up with 1.46-inch valve springs that offered 125 pounds of seat pressure (@ 1.78 installed height) and enough coil bind clearance to allow a .600 lift cam. The heads also featured chrome-moly rocker studs, ARP guide plates and 7 degree locks and retainers.
One of the keys to obtaining maximum performance from any combination is the camshaft. Lucky for us, TFS saw fit to choose a dyno-proven camshaft profile designed to work in conjunction with their high-flow aluminum cylinder heads. Working in conjunction with the intake manifold, the cam profile helps determine the operating rpm range of the combination. You will note that all of the TFS combinations, from 350 hp to 500 hp, included the same 23 degree aluminum heads, but specified different cam profiles to coincide with the recommended intake/carb combinations to produce the desired power level. We were looking for impressive power, so we decided to opt for the Pro Street combination that included a pretty healthy hydraulic roller cam profile. The dual-pattern TFS cam supplied in our Pro Street kit offered .558 lift (intake and exhaust) but a 246/254-duration split at .050. The 112 degree lobe separation angle should help tame the cam somewhat by improving the idle vacuum and broadening the torque curve without sacrificing power. The hydraulic roller cam was designed to fit in our early (non-roller) block. The cam provided the specified lift values working in conjunction with a set of 1.5 ratio roller rockers supplied with the engine kit. The roller rockers helped ensure that our valves were supplied all the lift specified by the cam profile. Stock stamped steel rockers are prone to inconsistent ratios, deflection and even breakage, none of which are desirable qualities in a performance rocker.
As mentioned earlier, TFS specified that the Pro Street combination be run with an Edelbrock Performer RPM Air Gap intake and 750 Holley (or Barry Grant) carb. Though the highlights of the TFS engine kit were indeed the hydraulic roller cam and aluminum cylinder heads, the kit included a great many other smaller, but no less important, components. Our TFS Pro Street kit also included a pushrod length checker to verify the required pushrod length with our hydraulic roller cam and adjustable roller rockers. We liked the fact that the kit also came with a complete gasket set, including everything needed to install the new heads, cam and rockers onto the awaiting short-block.
TFS also includes a new double-roller timing chain, ARP head bolts and the necessary cam button spacer and locking plate for our hydraulic roller cam. The cam button and spacer were used to limit cam walk, something necessary when installing hydraulic roller cams. Flat tappet cams lobes are angle-ground to keep the cam from walking forward. Hydraulic (and solid) roller cams do not feature this angle on the lobes, so some method of retention is necessary. The provided cam button rested against the front cover to limit cam movement.
To put the engine kit to the test, we installed the complete system on a typical 350 short-block. The SBC featured a cast crank, forged rods and forged flat-top pistons with valve reliefs. The block was of the more desirable 4-bolt main variety, but that was more of an unnecessary luxury at this power level. The TFS hydraulic roller cam and lifters were installed, but only after checking proper cam button clearance. Using our handy dandy pushrod length checker, we mocked the TFS heads and rocker arms in place then checked for the optimum pushrod length for our combination. This, as well as the cam button measurement, would be unnecessary when installing a standard hydraulic flat tappet cam. We just liked the idea of having improved ramp rates and reduced friction offered by the hydraulic roller profile. Using the supplied gasket set, we installed the TFS aluminum heads using the supplied ARP head bolts. It sure was nice not to have to search for all the hardware and gaskets while performing the install. Next came the ARP rocker studs, the 1.5-ratio roller rockers and finally the RPM Air Gap intake, Barry Grant 750 carb and MSD distributor. We finished off the combination with an electric fuel pump and a set of Hooker 1 3/4-inch (street rod) headers feeding a 3-inch dual exhaust system (basically collector extensions).With our motor at the ready, we put the TFS Pro Street Engine kit to the test on the dyno. After a brief warm up, the 350 Chevy pumped out some impressive power numbers, even more than expected. The 445/405 designation for the expected peak horsepower and torque numbers by TFS was, to say the least, very conservative. Our 355 Chevy bettered the advertised horsepower numbers offered by the supplied TFS literature at just 4900 rpm. Equipped with the TFS Pro Street heads, cam and roller rockers, our 355 Chevy produced 506 hp at 6100 rpm.
Every bit as impressive was the torque production, especially considering the rather wild cam timing. Rated to produce 405 lb-ft of peak torque, our 355 Chevy never produced less than 420 lb-ft and offered a peak torque reading of 463 lb-ft at 5000 rpm. Credit the torque producing nature of the dual-plane intake used on the combination for the impressive torque production. In retrospect, we would like to have seen what the combination ran like with a single-plane intake, but had no time to test the theory. Were this motor going in a street car (and not just a dyno exercise) we probably would have chosen a slightly smaller cam profile. If cost were an issue, we'd opt for one of the less expensive hydraulic flat-tappet cam combinations, but there is no denying the impressive results offered by the TFS Pro Street package.