Basic Tips For Modifying Your Chevy Truck
Ok. So you bought your used Chevy. It's got the 350 you wanted, so you can tweak it a little. Plenty of things to do to a small block Chevy for more power. You don't want to do too much, and you want to keep it smog legal. Lift laws are popping up all over the US, so that may be a consideration in building up your truck's suspension. Maximum allowable tire size laws, based on GVWR are in effect in many states. It would be a shame to build a truck that you could never drive on the street. If that's your goal, then good. Go as tall as you want. I personally, wouldn't put larger than 36" tires on a full size Chevy. I recommend a maximum of 6 or 7" total, suspension and body lift. A 4" suspension lift, and a 3"
body lift, fine. A 6" suspension lift, perfect. Body lifts have their perks, as well as downfalls.
The biggest drawback of a body lift, is it's harder to reach the motor when you open the hood. A bonus? You can change your spark plugs easier than ever, through the wheel wells. You can easily get your hands up near the top bellhousing bolts. More room near the distributor too. Careful when loading the bed if you have a body lift. Stock, the bed sits directly on the frame rails. With a 3" body lift, the bottom of the bed, will be 3" away from the frame rails. Odd that mini truck kits come with little 3" tall pieces of steel, that must be welded to the underside of the bed, to support this area. Full size lifts, do not include these. A load of 2x4's is fine, the weight is distributed evenly, and supported. A ton of crushed stone, may buckle the bed, directly over the wheels. It may not. I'm not willing to take that chance. Are you?
The benefits of a suspension lift, are less in number. More wheel travel, and articulation are benefits. The ability to mount larger tires on the rig is another. Wheel travel is the biggest benefit. Depending on the lift components, and maker, a suspension lift can actually improve your ride. The best lift configuration, in my opinion, is a sorted type of kit. The perfect Chevy doesn't get it's bed loaded with a ton of crushed stone often. If it does, then you want a kit that includes blocks for the rear. If you have a Blazer, Burban, or a pickup you don't plan on loading up, get a softride kit with 4 new leaf springs. This will reduce the likeliness of spring wrap.
Drivetrains. Well, you have your 350 motor. The best trans? The TH400 automatic. The best transfer case? The NP 205. The best rear axle? The GM 14 bolt, with the 10 1/2" ring gear. It's a full floating design. It's ring gear is actually larger, than the Dana 60's, which is 10 1/4". Up front, 1/2 tons, and 3/4 tons, used the GM 10 bolt. These are fine axles. A Dana 60, would be the best candidate for a swap. I'd keep the GM 10 bolt. Older GM's used a Dana 44 up front, also a fine axle. Now we know the strongest drivetrain.
The 350 needs some pep now. Remember, a truck with a motor that has 90,000 miles on it, isn't the best candidate to hot rod. Theory, the weakest link is the link that gives. If you beef up your whole top end, the weak link is you motor's bottom end. The increased stress may be too much. The first improvement, would be an intake manifold. This is a truck, not a 1/4 mile car. You want a dual plane type manifold. Designed to improve the low end of your rpm range. The Edelbrock Performer, is a perfect example. The Edelbrock Torker, is a single plane manifold, an example of what you don't want. To compliment the increase in intake flow, the exhaust flow should be increased. A set of Edelbrock Tubular Exhaust, similar to headers would be a good choice, as would headers. Just be sure they have a "bung" for you to screw in an Oxygen sensor. There are many manufacturers. I used Edelbrock as an example, because the part names are widely known. A high flow catalytic converter, and a cat back exhaust system, round out the package. You can use your stock carob or TBI. Many aftermarket carbs are available. Be sure the one you choose, is emissions compatible. If you think you want, and need a Holley 750 double pumper, think again. That's for the 1/4 mile car, not the trail. A 600, 650, or 700cfm carb, with vacuum secondaries, is what you want. Be sure to keep all emissions equipment in tact. A roadside spot inspection, could get your rig impounded fast if you don't. All of the engine mods I listed, can be done in your driveway, except the exhaust.
Those of us that are more handy, could do it all at home. A replacement cam, is an option, but not the average do-it-yourselfer's task. All the work doesn't have to be done at once. I like to get all the parts I need, to do a job like this, then do it. I may take months to get them all together, then work at installing them until I'm done. No matter how you do it, the end result is worth it. ~Chuck
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