Re: 68 Big Block Camaro.. Real Big Block Car????
CRG has a lot of good info. this may help. Q: How do I recognize the differences between first-generation high-performance models?
A: Here are a few of the more distinguishing characteristics. There are many other clues, both positive and negative, that are better explained in the more recent CRG Visual ID HyperTables, one for each year: 1967, 1968, 1969.
All 67-69 big-block cars are Super Sports, except for COPO models or dealer-modified cars like Yenkos, Baldwin-Motions, Nickeys, Danas, etc.
A car that originally came with a big-block engine, even if the engine is absent, will often still have the original big-block heater box, which is distinctly different from that of the small block or L-6 engine. The big-block heater core inlet and outlet penetrate the cover, whereas the small-block cover is unpierced - with the inlet and outlet coming through the firewall adjacent to the inboard end of the cover.
All 67-68 original 350 engines were Super Sports.
Original 67-69 302 engines were only installed on Z28s.
Original Muncie and THM400 transmissions were installed only on performance models of various types (the THM400 was only applied to big-block cars).
All 1968-69 performance models have multi-leaf rear springs. The Z28 typically received 4-leaf springs and all models with 350ci or higher displacement engines (including the L65 350ci 2BC engine) typically received 5-leaf springs. The 1968 L30/M20 also received multi-leaf springs. Spring count was weight dependent, however, and it is possible for certain Z28s to have a 5-leaf spring, or for a L30/M20 or 350ci engined car to have a 4-leaf spring.
All 67-69 performance models, with two exceptions, have the 8.875 inch diameter rear axle (aka, the "12-bolt" axle). The first exception is the 1967 L30/M20 from model start until approximately Dec '66, which came standard with a 10-bolt axle. Also (though 12-bolt versions have been noted and we are still researching this) many '69 SS-350s with the Powerglide transmission were equipped with a 10-bolt axle. However, it was possible for any '69 Camaro with the L48 or LM1 engine that would have normally had a 10-bolt axle to be optionally provided with a 12-bolt rear axle. 12-bolt axles were also installed on any car with the 1969 JL8 4-wheel disc brakes.
All 1968-69 models with the rear brake proportioning valve in the line under the drivers side door, are performance models. However JL8 4-wheel disc brake models did not use this valve, and so absence of the valve, in the case of a JL8 axle, does not mean that the car is not a performance model. There are also reports of a few very early 1969 performance models that were built without these valves.
A car with original factory air conditioning cannot be either a Z28, a L78 SS, or a COPO car (GM did not apply A/C units to solid-lifter motors).
Les Dixon member #68 1968 camaro RS/SS MR code L34 396 air convertible