1987 Dodge D150 pickup 5.2l 318 cid
OK, OK, OK
Start with the basics:
You have a 1987 D150 with a 318 in it. It is a carbureted, manual fuel pump, 9.2:1 compression ratio, that came with flat top pistons and the closed chamber 302 heads, and roller lifter setup, all from the factory.
Simple first step is to put a camshaft of your choice (not too big), 4 bbl. intake manifold, and something like an Edelbrock 1406 4 bbl carb on it, it's jetted properly for your 318 right out of the box.
1987 318 Roller Lifter engine pictured below:
These roller 318 engines came factory with the 318 closed chambered heads pictured like these below:
Great setup using what you have.
Next step would be to start buying lots more parts, and spending lots more money.
Good luck on your project.
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