Tech Area

84 Caddy Not Recommended

Question: I notice on your site when talking about 4.9 swaps you say 1985 up. Is it not possible with a '84 car?

Answer: It is possible. However the '84 cabin wiring harness (C-500), which connects in the center of the engine compartment, only supports a single injector and is not compatible with ANY "V" engine (it would be against the exhaust manifold). If changed to an '85 or later (that connects behind the battery), then the '84 front and rear light harnesses are not compatible with the '85 cabin harness. Other problems are the cruise control system and the AC system.

Results are that ALL wiring in an '84, along with under car AC lines (if AC is wanted) and instrument cluster (if cruise control is wanted), should be changed to that of '85 or later.

Exceptions would be a Quad 4, or a carbureted, single wire distributor "V" engine, that does not need the cabin harness connection.

We install the 4.9's with total Cadillac control of the sequential fuel injection and emission systems through the later C-500 connection. Therefore, changing an '84 to accept any "V" engine with AC and cruise control, could require about $1800 in additional expense.

Although we have done a dozen or so "V" engines in 84's (mostly 2.8-3.4's), unless the car has EXTREME sentimental value, it is usually cost effective to begin with a later model.

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