FIAT 124 Spider
Engine Maintenance + Modification
82
carburetor are collectively regarded as “boat anchors” and are always candidates for
replacement. Simply replacing the carbureted 2000cc head with one from a 2000cc fuel
injected or 1756cc engine will provide some improvement in efficiency.
The Spider 1756 head began life as a clean head, nearly identical to the 2000 FI head
described above. The 1756 head has smaller combustion chambers than the 2000
heads but is otherwise the same casting. By 1978 they had adopted a camshaft-driven
air pump and several emission control valves on the intake manifold. Unlike the 2000
carbureted head the 1756 never had the EGR port squishing the combustion chamber
and with little work any of the 1756 heads are desirable. One of the Lancia heads, the
1976 Monte Carlo (Scorpion) head, has larger ports than the other model years. The
1756 intake manifold is also desirable for the ADL, ADF, ADFA, DFEV, and DMSA
carburetors.
The Spider 1592 head was designed for, and mated to, the 1592cc engine used on the
1973 model year only. It is not laden with any specific emission control devices and is
really a clean head. If your vehicle has the 1592 motor (many were replaced with
1756’s) and you wish to maintain originality then this is the only head you can use. It is
otherwise not desirable for use on any other Spider.
The Spider 1608 and 1438 heads are clean heads with few or no emissions control or
other power-sucking devices added to them. They are slightly different that the later
series heads and, for the purposes of interchangeability (as described below), should
probably be kept on the engine they were designed for.
11.1.4 Interchangeability
The interchangeability of cylinder heads between the 1756 and 2000 Spiders is a true,
do-it-yourself, instant improvement. A clean 1756 head installed on top of the 2000
block (carbureted or fuel injected) results in a compression increase. Although not as
dramatic as the installation of high compression pistons, this can be done without pulling
the engine and requires the same amount of work as replacing the head gasket. The
difference being when the head gasket goes on the new head goes on top.
The 2000 FI head can also be installed on the 2000 carbureted engine. It will not alter
the compression ratio but will improve performance just by nature of a better, cleaner
design.
Other model years can be interchanged as well. The 1438 head is somewhat restrictive
and, with some minor welding on one of the coolant ports, can be replaced with the
1608 head. Experience has shown that most owners of these older Spiders are not
doing these upgrades as the performance gain is minimal. More suitable is the
installation of high compression pistons or other engine upgrades.
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