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.