Corvettes with RPO L88 were...
Corvettes with RPO L88 were essentially road race-ready cars the could be bought at your local Chevrolet dealer. Only 20 L88 Corvettes were sold in 1967, making them extremely rare today. In recent years documented examples like Dave Walter's coupe have fetched high six-figures at auction and in private sales.
Ignition was via Delco's reliable and effective transistor system, an option on other engines, but mandatory with the L88. The L88's distributor was tailored for high rpm usage and, unlike other transistor units, did not use a functional vacuum advance. Also unique to the L88 were its ignition wires, which were molded with a special heat resistant rubber compound.
In addition to transistor ignition, a number of other high performance options were mandatory with the L88. These included an M22 "rock crusher" transmission, so nicknamed because its more upright gear tooth angle made it especially noisy, while at the same time making it stronger. Completing the drivetrain was a G81 Positraction limited slip differential, available in ratios ranging from 3.08:1 to 4.56:1. Even lower and higher ratios were also available as special order items. In keeping with the L88's nature another mandated option was the F41 heavy-duty suspension. Included in the suspension package was a thicker front antiroll bar, stiffer front and rear springs, and specially valved shock absorbers all around.
All L88s were built with J50 power assist brakes, a fact that surprises some people. Why put something that adds weight and was only a luxury that racers really didn't need? The answer is simple. L88 Corvettes were also required to have RPO J56, a heavy-duty brake package consisting of special dual-pin front calipers, special heat insulators on all caliper pistons, a proportioning valve mounted beneath the master cylinder, and metallic brake pads. While the metallic lined pads were highly wear resistant, they only functioned properly when quite hot. When cold they hardly were able to stop, and thus made power assist absolutely mandatory.
As important as what was required with the L88 package was the list of equipment that could not be had with it. Luxury items like air conditioning and a radio were forbidden, and normal equipment such as the heater/defroster system and even the engine fan shroud were deleted.
According to an article that appeared in volume 10, number 3 of Corvette News, prohibition of luxury appointments and deletion of certain normally standard components was done to "cut down on weight and discourage the car's use on the street."
To further discourage its use on the street, a warning sticker placed inside the car pointed out that the radically cammed, high-compression engine required fuel with a research octane number of at least 103. Even back in the good old days fuel of this quality was difficult to find and expensive when it could be had.
And for those few who still might be tempted to buy an L88 Corvette for highway use, Chevrolet added a couple more impediments. The first was price. The engine alone added $947.90 to the bottom line in 1967. When other mandatory options were added in the price of the base car was increased by nearly 50 percent! If all else failed, the final deterrent was the L88's advertised power rating. It was quoted at 430 horsepower, five less than the L71 427 that cost less than half as much. Why would any speed-seeking buyer in his right mind pay more than twice as much for an engine that made fewer ponies?
The answer of course is that he wouldn't, but did the L88 really make less power than the L71?
The quoted output of 430 horsepower was measured at 4,600 rpm, well below the engine's peak. Also, L88s were delivered with the same cast iron exhaust manifolds and full exhaust systems as every other big-block. While this configuration was fine for other engines, it utterly strangled the L88. Given its cam profile, port configuration, and other internal design parameters, the L88 craved an unrestricted exhaust path and without it output really did peak in the area of 430 horsepower.