Tips for Building an Old V8 Engine

So you have decided to build the engine in your classic instead of sourcing out an expensive crate motor or having someone else do the work. Great! However, there are a few things to keep in mind if you are wishing to warm up the mill a bit and not simply build it back to stock specifications. The first thing to do is decide what you want from the vehicle. Is it a racer? Is it a Sunday cruiser? Will it be towing things?

CAMSHAFT

If the engine is in an old Mustang, Camaro, or Duster for instance, and you want it to move, then choose an aggressive camshaft from a reputable company such as Competition Cams, Isky or MOPAR Performance. If it is more of a cruiser, a milder camshaft will be fine. Do some research and talk to a few experts before choosing a grind, because the camshaft you choose will greatly affect engine performance and mileage. A really aggressive camshaft will rob vacuum from the engine, so power brakes may be affected.

HEADS

Next, decide whether you would like to do head work which will allow the engine to breathe easier at higher RPMs. A simple porting and polishing job can bring quite a few horses to the stable, which will really improve the performance of the engine. Almost any old V8 engine can benefit from some head work. If the car is a large, daily driver such as an old Plymouth Fury or Chevrolet Impala, the heads won't require as much work as they might in a 500 horsepower Chevelle or Mustang. Again, talking to an expert in the area can really help in making the correct decision.

PISTONS

Choosing the pistons to use in your V8 rebuild is a bit easier, but keep things like compression ratio and over bore in mind. Boring is when a machine shop widens the cylinders slightly to provide a new mating surface for the piston rings. The pistons and rings must match the bore job, or they simply will not work. The most popular bore sizes are .030", .040" and .060", but some engines cannot be bored very much so ask questions before going with a big bore. Order pistons in the exact oversize that you need so that they slide into the cylinder. The shape of the top of the piston greatly affects compression ratio, as well. Dome-top pistons will raise the compression quite a bit, while flat-top pistons will normally retain the stock ratio, providing the heads and block are not modified at the gasket surface.

FUEL DELIVERY

The next thing to consider is the carburetor and intake manifold. Popular mild units for the street include Weiand and Edelbrock Performer manifolds, and it is very common to attach either Edelbrock or Holley four-barrel carburetors to them. For smaller-cube engines such as the Chevy 327 or MOPAR 318, 600 CFM units are all you will need. For large cube small or big blocks that will live at higher RPMs, it may be necessary to step into the 750 CFM models. CFM stands for Cubic Feet per Minute of fuel delivered. Too much or too little fuel being administered to the engine will greatly affect overall performance.

EXHAUST

Headers are a very popular and relatively cheap upgrade to any old V8 engine. They can be had at a wide variety of prices, from about $120.00 all the way up to $700.00 and more, depending on the application and quality. Most small block V8 engines can get away with headers and 2 ¼ inch pipe with quality mufflers and gain quite a bit of power. A big block or high-horse engine may require 3" tubing or greater and a very free-flowing muffler such as Flowmaster's top line units.

Now that you have the basics, start surfing the Net and making phone calls to see what combination of the above components will work best for your old ride. Also, keep in mind smog laws when building the engine, because an overly built V8 that has to be smogged could really run into some trouble.