Engine Maintenance and Modification Bradley Artigue
FIAT 124 Spider Engine Maintenance + Modification - Artigue.com
FIAT 124 Spider Engine Maintenance + Modification - Artigue.com
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FIAT 124 Spider<br />
<strong>Engine</strong> <strong>Maintenance</strong> + <strong>Modification</strong><br />
Another option is adjustable camshaft wheels. These allow you to independently change<br />
the timing of each camshaft to match your requirements. This compensation allows for<br />
fine tuning of your engine to a degree not possible with stock components. Some of<br />
these wheels require modification of the cylinder head; check with your supplier.<br />
Adjustable camshaft wheels will add something new to your engine – complexity.<br />
Consider that factor <strong>and</strong> speak to people who use them before installation.<br />
11.1.7 Big Valves<br />
Many suppliers sell big valves <strong>and</strong>/or peformance heads (meaning a stock head that has<br />
been cut to fit big valves <strong>and</strong> ported for better airflow). Simply buying the big valves <strong>and</strong><br />
cutting the head to accommodate them or buying a performance head will not result in<br />
any huge performance increase. The fuel delivery system has to be capable of bringing<br />
more air <strong>and</strong> fuel into the combustion chamber. Big valve heads that are ported <strong>and</strong><br />
matched to a ported intake manifold will allow more air <strong>and</strong> fuel into the engine. A larger<br />
carburetor will also be required on most engines.<br />
11.2 Intake Manifolds<br />
A variety of intake manifolds were installed on the carbureted Spiders. They followed<br />
two basic designs as described earlier in this book, dual-plane <strong>and</strong> single-plane. To<br />
recap, a dual plane manifold has two chambers inside of it, one is small <strong>and</strong> the other is<br />
large. The larger one is the primary plenum <strong>and</strong> services the main throttle of the<br />
carburetor. The smaller one is the secondary plenum <strong>and</strong> services the secondary<br />
throttle. Dual plane manifolds are designed for optimal operation of the secondary<br />
throttle of pneumatically-operated carburetors. Single-plane manifolds have one interior<br />
space. Fuel <strong>and</strong> air from both throttles is delivered from this one large space into the<br />
intake runners <strong>and</strong> then the combustion chambers.<br />
With the exception of the 2000 series all of the manifolds are quite good. On the 2000<br />
Spider the intake manifold should be used with the ADHA (stock) carburetor only. The<br />
casting is such that the secondary throttle opening is too small for any other carburetor.<br />
For pneumatic carburetors fitted to the earlier Spiders you should plan to use the stock<br />
manifold for the model year <strong>and</strong> carburetor, for example, use the 1608/1592 manifold<br />
with the 28/36 DHSA carburetor.<br />
In all cases it is realistic to block off all of the ports except for the brake booster inlet.<br />
Keep in mind that if you plan to keep emissions control devices that rely on manifold<br />
pressure you can’t block off their ports.<br />
11.3 Ignition<br />
Running with points? There are a few decisions that need to be made about your<br />
ignition system if you are looking to improve things. Improvement can often be made by<br />
simply making sure your entire ignition system is working properly. Thad Kirk, a long<br />
time respected FIAT owner, has articles on points ignitions on www.mirafiori.com. He<br />
notes that a well tuned points distributor provides reliability <strong>and</strong> performance right up<br />
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