How to Rebuild a 350 Chevy Engine

350 Chevy Engine
Written by Ken Coul

It’s time to take that old Chevy 350 and rebuild it to the optimized perfection of performance. Now, most car enthusiasts have access to a well-stocked car mechanics tool kit, which is basically a large room full of stuff that most people don’t know how to hold properly or pronounce their names. If you don’t have access to this kind of tool range, don’t start. While most common tools can be used to rebuild an old Chevy 350 to a working model, there are some tools and expertise that you will need that are not found on a shelf of your local hardware store.

Now let’s take a look at the small block Chevy 350 Engine and then discuss how we can pump it up to produce a whopping 400hp of pure purring enjoyment.

How to Rebuild a 350 Chevy Engine

The Chevy 350 Small Block Engine

The Chevrolet small-block engine is a series of V8 engines that were in normal production at the Chevrolet Division of General Motors between the years 1955 and 2003, all models using the same basic engine block. This engine was called a “small block” due to the comparative size relative to the much larger Chevrolet big-block engines. These engines displacement spanned from 262 cu in (4.3 L) to 400 cu in (6.6 L).

Refurbishing

All engines cost money to build, and a more controlled budget can lead to some interesting results, even producing some powerful results using aftermarket parts. However, the state of the engine and its components is what base your costs. Do you need to re-machine every part? buy new parts? In this guide, I will show you how a basic engine, in reasonable condition can be rebuilt for under $1,000 and produce a whopping 400hp.

Now, you might say that rebuilding a 350 engine to produce 400hp is easy, well you would be right. It is easy if you don’t mind the costs, but what if you wanted to rebuild that engine at a very considerate and comfortable price?

Add to this amazing equation the fact that this price includes all the parts, the engine block, the aluminum cylinder heads and, well everything.

Finding your Engine and Parts

The first thing you need to do is find a good engine to base your work. Since you don’t want to buy all the parts off the shelf and end up paying a small fortune, you will need to visit some scrap yards and check out the various engines that are still in good shape. You don’t need to buy a complete engine, but this is actually the best way to start off because you might find a lot of salvageable parts coming with the entire engine.

Most scrap engines that are worth their weight in dollars are still found n the vehicle, so you will need to come prepared to remove that engine from the chassis. These engines will cost you around $225 and maybe an extra few dollars for a core. Take into account that there are loads of Chevy small block engines out there, and they are even ready to run as-is, so with just a little bit of understanding, you can pick up an entire 350 small block with core for a very reasonable price.

If its power you want, then go find a Q-jet, you will need this model to reach the 400hp mark. Take into account, when you search scrap yards you need to be sure that the engine is present in its entirety. This includes all the necessary appendages such as the air cleaner assembly, the oil pan, the fan and the flex plate. Also, make sure you get the motor mounts and starter and try to get all the accessories too.

Choosy is Best

Once you have found your preferred engine of choice, its time to check into it for more details before you buy it. This means that you need to open the radiator cap or in a radiator hose for antifreeze, the last thing you want is a rusty radiator or thermostat housing unit. Next, check the dip stick for burnt oil, and if you want to be extra particular, remove the drain plug or check the oil pan for sludge. This might require you to check a valve too; you don’t want a burnt engine instead of one that just needs an oil change.

You might, no; you must check the spark plugs for burnt oil, and don’t be fooled by fresh plugs. After completing this preliminary inspection, try to turn the crack using a ratchet, and if it rotates easily, you have a winner on your hands.  Now buy the bulk and get to your machine shop.

How to Rebuild a 350 Chevy Engine

Chuckling and Stripping

The first thing you want to do is check your engine. You will need to perform an oil pump test to check whether you need a new oil pump or not; you do this by filling the oil pan with synthetic lubricant and spin the driveshaft using a standard electric drill. If you get 60 psi, you are lucky, and you don’t need to change the oil pump.

Now you need to strip this baby down to its core components and start to rebuild every part. So here goes:

Cylinder Heads

It is cheaper to buy new cylinder heads than to machine the old ones, the time taken to machine old heads can be costly, and they will not produce the power you seek. Make sure you buy Pro-Comp heads with a valve spring upgrade, this will get your motor to run up to 6,500 rpm without a valve float. The cylinder heads I chose were the Pro Comp aluminum castings intake ports: 190 ccs, exhaust ports: 70 ccs, with valve combination of 2.02/1.60. The heads are significantly lighter than the original factory heads, and they provided a 250-cfm flow for the intake and a 190-cfm flow at the exhaust. If you want to increase these flow rates, you can perform a CNC porting, but that will increase the costs as well.

Pushrods

Now we come to the pushrod, which needs to be replaced, and that means we need a set of 7.4” pushrods that are not expensive to find, to use with stock guided rockers. This is significantly cheaper than using hardened pushrods made of chrome-moly.

Manifold

I always suggest you buy a new manifold; it is proven to improve performance. Throw away the old one and buy a single-plane Hurricane manifold from Professional Products, these are tested and proven parts.

Camshaft

If its power you want, then get rid of the old camshaft and buy a new aftermarket part. The more recent models come with a hydraulic roller cam if you are lucky you can then re-use the stock roller lifters, but you must buy some hydraulic roller cams, and there is a lot to choose from. My suggestion is Xtreme Energy XR282HR, this part gives you a 0.510/0.520 lift split, with a 230/236 duration split and 110-degree lobe separation angle.

Timing Chain

You can either replace this at extra cost or if the timing chain looks good, use it and save some extra cash.

Gaskets

When assembling you will need new gaskets for everything, I don’t like using old ones even if they look new. The best thing to do is search for a complete gasket set for your specific model; the sets are not expensive.

Cleaning

Before you rebuild your engine, you will need to wash it and scrub it clean. Also, check the original engine internal parts for integrity issues. Once your parts are all cleaned, shiny and dry, you can start to assemble. Don’t forget to have enough lubricants at hands reach.

Installation

Once you have all the parts, you start to reassemble your unit:

  1. Engine Block: make sure its clean, dry and ready for installation.
  2. Camshaft: make sure you have your aftermarket part ready to install
  3. Main Bearings: Install the 0.010-inch undersized main bearings and slather them with assembly lube.
  4. Place the camshaft into the engine block torque the factory bolts to 75 ft-lb.
  5. Install the cast-iron 0.040-inch rings on the aluminum slugs of the piston heads.
  6. Oil the cylinders and slide the piston/rod assemblies into place. Take note that there is a small dot on each piston to indicate which side faces the front of the engine.
  7. Now we install the hydraulic roller camshaft.
  8. Attach the retaining plate and button.
  9. Its head time: take the 64cc chamber head and lock it into place.
  10. Now attach assemble and install the oil pump
  11. It’s gasket time, don’t forget to use RTV sealant on the corners for extra security.
  12. Take the oil pan and fix it into place.
  13. Now its time to attach the roller valvetrain, and I used with a full set of these vertical link-bar lifters.
  14. Next, attach the rockers and pushrods.
  15. Attach the distributor, try to find a unit that has both a vacuum and mechanical advance and the magnetic trigger.
  16. The 350 engine carburetor is next, and you can find a lot of good deals, its all matter of choosing between price and pride.
  17. Finally, place the covers over the engine, these can come in all shapes and finishes, so it’s up to you what cover you want for your engine.
  18. Now its time to tune your engine and get it ready for full installation.