Modifying an LT1 Corvette - To Top It All Off

An Up-Close Look At Trick Flow Specialties' New 430HP LT1 Top-End Kit

Jay Heath Nov 26, 2009 0 Comment(s)
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Supporting Hardware
To minimize last-minute parts-store shuttling, the kit comes with a complete set of gaskets and all required fasteners. You will need to supply your own timing chain, 1.6-ratio rocker arms, fuel injectors, and pushrods, all of which can be obtained from TFS or its parent company, Summit Racing.

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In our case, Summit supplied a GMPP Extreme Duty Timing Chain Set (PN 12370835), a single-roller setup that uses a steel water-pump gear as well as steel cam and crank sprockets. Note that while this unit is designed for '95-up LT1/4 engines, it can be used on earlier versions with some modifications.

TFS, meanwhile, sent us a full set of its own 1.6-ratio roller rockers (PN TFS-31400513), which feature CNC-machined aluminum bodies, needle-bearing fulcrums, roller tips, and a machined relief for improved valve-spring clearance. Best of all, they come in a natty black-anodized finish that's guaranteed to wow onlookers any time you pull the valve covers.

To meet the fueling requirements of our power-enhanced LT1, the company also kicked in an octet of 30-lb/hr TFX fuel injectors (PN TFS-89030). In addition to their increased flow rating (the stockers are rated at 24 lb/hr), the TFS squirters incorporate upgrades ranging from Viton fluoroelastomer O-rings and EV1-style wiring connectors to low-magnetic stainless-steel bodies and 100 percent duty-cycle testing.

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The final elements of our particular package included pushrods and a TFS pushrod-length checker. Noe recommends verifying this critical measurement prior to installation, as TFS engineers have observed considerable differences in length requirements among various years and versions of LT engines. To minimize downtime during our install, the company shipped us pushrods in two different lengths. After determining which one is right for our combo, we'll simply ship the unused set back to the company.

The Bottom Line
Offering top-quality engine upgrades is one thing, but doing it affordably is critical when dealing with an older vehicle such as the LT1 C4. Happily, TFS appears to have kept its target customer in mind when setting the package's list price, which comes in at $2,499.95. While that's not exactly couch-cushion money, it's a bargain compared with the cost of a full-on engine swap or trading up to a newer-model Vette. And besides, with 430 horses corralled under the hood, who needs a C6?

We left off last month's torque converter-installation story with a promise of follow-up testing, so when a cold front blew in recently and dropped temperatures into the low 50s, we headed north, deep into Gator Country, for a day of quarter-miling at Gainesville Raceway. Considering that our '96 coupe had already logged a best pass of 13.28 seconds with the low-stall factory converter, we were hopeful that our new TCI StreetFighter unit-with its approximately 2,800-rpm stall speed-would combine with the crisp, dry air to produce a legitimate 12-second pass.

Our initial run started out promisingly, with the fat (315mm) Nitto NT555R drag radials planting hard and hoisting the nose smartly skyward off the line. But just as the rear wheels were passing through the beams, acceleration fell off sharply, to the accompaniment of a woeful sputtering sound from the engine compartment. The car recovered quickly and completed the run, but the e.t. damage was done: the resulting 13.519 at 104.46 mph was more than a half-second off the desired pace.

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A glance at the glowing "Reserve" light beneath the fuel gauge confirmed the problem: the sheer violence of the launch had caused what little gas there was in the tank to slosh rearward, away from the pickup, temporarily starving the engine of fuel. After hying it to a nearby BP for a few gallons of 93-octane premium, we were ready to give it another go.


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