How do I get more power out of my 318?

Discussion in 'Engine & Performance' started by Dead Reckon, Aug 11, 2016.

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  1. crazzywolfie

    crazzywolfie Senior Member

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    heck i picked up a stock 4bbl intake and carb last year for free. i didn't need it but i wasn't going to turn it down.
    [​IMG]
     
  2. Sniper X

    Sniper X Senior Member

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    We know, but the problem always is the same. Someone asks about replacing a cam for more power and the rest of the motor is stock, so ensues the conversation of you can't get there from here. I've been involved in these discussions since I got my first car in 1974, a Chevelle SS with the 375 HP 396, and all my buddies who had bought small block Chevys or mopars all asked the same question. Back then it was a little easier because most small blocks at least had higher compression, and better flowing heads a d came stock with a 4 barrel.
     
    Last edited: Dec 31, 2016
  3. Yeret

    Yeret The Village Drunk

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    Magnum cylinder heads would be a nice improvement, however an improved-design set that won't crack between the valves will run around $600, not to mention the cost of converting the block to accept the heads. They'll bolt on just fine, but the valvetrain oiling is very different between a Magnum engine and an LA engine. If you simply bolt a pair of Magnum heads onto an LA block without proper conversion, you will destroy the valvetrain very quickly.

    You note that your distributor advance isn't functioning correctly. This will yield similar results to the "death flash" on the Magnum engine. In other words, the harder you try to accelerate, the "heavier" the boat anchor that is now your engine becomes. Fix this or you will never realize anything that even remotely resembles performance.

    Other vacuum leaks? Any single vacuum leak can screw with how an engine performs, let alone what several will do. Fuel-injected engines can adapt to small leaks depending on where they are. A carbureted engine can't detect and adjust to any leak so even a small leak could lean out your mixture.

    Factory engine? Exhaust "upgrades" won't net you much if anything at all. It's actually quite easy to kill your low-end power while picking up miniscule top-end gains by fiddling with the exhaust. DO NOT fall into the "true dual straight pipe" trap. Sure it looks cool, but there is no easier way to 1. kill your low-end torque, 2. make your truck sound obnoxious as hell. Stick to a single exhaust with slightly upsized pipes all around and you'll pick up some mid-range without significantly affecting low-end. Summit offers El Cheapo headers for Magnum heads for $200 and these are a direct fit on LA heads. Nevermind the gaskets that come with them, spend a little extra for quality gaskets and you'll thank yourself later.

    Good choice on the carb. As wolfie said, it's nice to see that you aren't trying to "overcarburete" the engine. That cfm rating sounds appropriate for a mild 318.

    No cam? No good. If you're gonna swap to a four-barrel and appropriate manifold and open up the exhaust, that "sausage" grind is going to bottleneck the entire setup. The later Magnum OEM cams were pretty soft, but they were still good enough to generate 245 horsepower. Your setup is rated for 140 horsepower, so I can only imagine how soft the cam is in that.
     

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