It’s no secret that almost any engine can find missing horsepower if the cylinder heads are the recipients of performance-enhancing massage work. Even a stock engine that is used solely for daily transportation will typically enjoy the increase in power and improved drivability that is delivered by improving airflow through the cylinder head.

That brings us to the reason for this article. When it comes to deciding if you should you rebuild and modify the cylinder heads you have, or buy a set of new-and-improved castings, we want to eliminate any confusion. Just like any other question that pertains to your engine, it all depends on what you expect your engine to do. We asked the question of whether to rebuild or get new to both Eric Blakely of Edelbrock Performance, and Kevin Willis of Automotive Performance Engines of Auburndale, Florida.

While you might expect a manufacturer and a rebuilder to have two entirely different opinions, the truth is, they are fairly agreeable with each other. Blakely told us, “Edelbrock does not offer a rebuild service for our cylinder heads. We do sell all of the components individually for a consumer or shop to purchase and do the rebuild. We understand that consumers on a budget are going to find used cylinder heads in junkyards and online, so Edelbrock has chosen to support the engine builders by giving them the business and opportunity to have consumers bring them our cylinder heads for servicing. This is why we have chosen to offer all of the components for each of our cylinder heads for purchase.”

According to Willis, “Companies that sell complete, ready-to-run cylinder heads don’t necessarily offer a rebuilding service, that’s where I come in. If you already have a performance-oriented head that just needs rebuilt, rebuilding can be cheaper than buying new. If you need a performance cylinder head to begin with, it’s hard to beat the bang for the buck you get with those aftermarket heads.”

When it comes to purchasing stock-style cylinder heads that are ready-to-run, we contacted Russ Flagle of Aerohead Racing Components, and asked him about how he is able to sell his complete, refurbished cylinder heads so inexpensively. “The rebuilt heads that we sell are factory castings that are bought as a core and then rebuilt. We buy our parts in such large quantities, that we get a big discount, and are able to pass that on to the consumer. It’s tough to beat the deal we can deliver. Our heads are not built to be a performance-oriented cylinder head, but rather, an inexpensive replacement that can be worked on.”

The discussion about rebuilding or buying new will never get a definitive final answer. Car guys are set in their ways, and since there are so many different opinions, we would not try to end the argument, but simply present some facts that apply to both sides of the discussion. Ultimately, we’d like our readers to decide what is best for them and their engines.

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When having your heads rebuilt, consider the cost of replacing valve guides or liners, installing valve seats, and what kind of valve seals you want.

Freshly Rebuilt

There are two ways to accomplish rebuilding cylinder heads: Buy an already remanufactured cylinder head, or have it rebuilt by a local shop. While you might think the outcome will be the same, think again. When dealing with a supplier of ready-to-run remanufactured heads, keep in mind that the heads have come off of an assembly line-like situation. Sometimes you can special order things that are done, but not always.

Sure, the head will have been rebuilt to within an acceptable tolerance within a factory spec, but if you’re looking for something a little better than factory spec, in this case, you can’t get it your way. Companies that sell remanufactured cylinder heads keep costs low by working within a set of specific parameters, and those parameters dictate a specific build guideline. That brings us to your local machine shop.

When working with a local shop, your wallet is usually the limiting factor. Also, when choosing a shop that is going to rebuild your cylinder heads, there is usually a big difference between using a competent shop, and someone’s “friend.”

The next thing to consider are the parts you choose when rebuilding the cylinder heads, as this can also have a huge effect on the end result. While everyone likes to throw around popular names of certain parts manufacturers, are those big name race parts really necessary for your application?

Regardless of what parts you ultimately choose to include in your rebuild, there are certain aspects that must be addressed. Are the existing heads cracked or warped? Are the valves and/or the valve guides shot, and are the heads compatible with unleaded fuel? These aspects determine what will require machining … and we haven’t addressed buying parts like valve springs and seals, yet.

We asked Willis if the availability of ready-to-run cylinder heads from the aftermarket has hurt his business. “Not really, most of what I do is performance-oriented, and those guys typically bring their stuff in each year for me to check out. Before you can rebuild a cylinder head, you need to make sure it is even rebuildable,” he said.

A cylinder head rebuild starts by disassembling and cleaning the head, which Willis said is then magna fluxed for cracks ($75/pair). More often than not, he will have to machine the block-mating surface to eliminate any warpage ($80/pair). Once that is complete, Willis inspects the valve guides. We have never seen a cylinder head get rebuilt that didn’t need at least two or three of the exhaust guides replaced ($10 each plus cost of guide. Usually, all exhaust guides will need to be replaced). Over the years, the up and down motion of the valve in your engine might also have worn the valve stem. If this is the case, the valve will need replaced ($15 each, and on average, at least three will need replaced). Even if you do not need to replace any valves, the ones you have should at least be reconditioned ($200/pair cylinder heads).

While you’re at it, if the cylinder heads are not compatible with unleaded fuel, a set of hardened valve seats will need to be installed ($15 to $25 each). In case you haven’t noticed, the cost of rebuilding a cylinder head is escalating — but we’re not done yet.

If you want to do the job correctly, you will need to add in the cost of machining for new valve seals ($50/pair cylinder heads), the cost of the actual seals ($80/pair cylinder heads), and then a valve job and assembling each cylinder head ($200/pair cylinder heads). In fact, even with just the basic items we have listed, when it’s all said and done, you will have approximately $900 to $1,100 of your hard-earned cash invested in a pair of stock cylinder heads.

All About The Options

The previously mentioned machining processes are mandatory during a rebuild, but if you want to improve your cylinder head, you might want to consider some porting work. If you do, Willis says you can figure on adding an hourly shop rate from approximately $75 per hour or more, for approximately 15 to 20 hours of work. Adding screw-in studs is a traditional upgrade, and at $120 per pair cylinder heads for machining, plus $50 for the studs, this isn’t a cheap upgrade. Finally, a lot of guys want to add push-rod guide plates, and for $20, you can.

The cost of rebuilding a set of cylinder heads with your local machinist can get very pricey, but there are times when the stock cylinder head is the only rational alternative.

Let’s face it, having the “numbers-matching” cylinder head is a necessity when doing a proper restoration, and we’ll admit that sometimes it is really cool to see a small-block with a set of original “double hump” cylinder heads make an impression at the drag strip.

A Custom Situation

While the previous outline of services does outline the approximate costs to rebuild a pair of used cylinder heads to factory specifications, sometimes, a performance cylinder head is needed. Unfortunately, outlining the cost of rebuilding a cylinder head for all-out performance is not within the scope of this article, as we are only focusing on cylinder heads for street and mild-performance applications. But suffice to say, the cost can get exponentially higher than that of a stock rebuild, depending on how fast you actually want to go.

While companies like Edelbrock do not offer rebuilding services, they do have all of the parts available to rebuild their cylinder heads. In this instance, if you already have a pair of performance-oriented cylinder heads that just need a thorough inspection and refresh, rebuilding those will probably be a less expensive alternative.

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Machining costs can add up when rebuilding cylinder heads. This head needs a valve job, the spring pockets machined for larger springs, and then resurfaced.

Now that we have probably scared you by showing how expensive it can be just to rebuild a set of cylinder heads to stock configuration, we also wanted to alleviate some of those concerns, and show you some viable alternatives. Buying a set of heads that are already prepared for installation is a really great way for you to save some of your money.

Understanding The Difference

The shops we have listed that supply ready-to-run cylinder heads have developed a process and they buy parts in bulk, this combination enables them to keep their costs low.

One decision you will have to make if you are contemplating the purchase of an aftermarket cylinder head is whether you want to buy a cast-iron unit, or an aluminum head. There are various cylinder heads available, and there is even some confusion surrounding what is available. Some of this confusion is brought about by people using the terms “bolt-on” and “stock replacement.” These two terms are sometimes used incorrectly, which exacerbates the confusion.

A “stock replacement” head is just that, stock. The ports and mounting points for the auxiliary factory components are just as the factory designed. This means the stock rocker arms, valve covers, and external brackets will attach just like they did from the factory. A head that is “bolt-on,” generally means that while they can be installed with the correct bolts, it does not mean that they are a “stock replacement” head, and that all OE pieces will fit.

When talking about the differences between a stock replacement and bolt on cylinder head, you also need to understand that you are dealing with two different types of heads from a performance stand point.

A stock replacement-type head will probably not deliver any performance characteristics, if that is what you are looking for, they are stock. A bolt-on head on the other hand can — and many cases, usually does — possess characteristics designed to increase performance.

When you’re looking for a good-quality cylinder head for your street or mild-performance car, the following options of already assembled cylinder heads are probably going to be a less expensive alternative than having a set of used, swap meet acquired cylinder heads rebuilt at a local shop.

That being said, we do realize that there are going to be some guys that just do not want to put a set of aluminum heads on their engine, and that’s okay. That still doesn’t mean you can’t save a little money, and find a new or remanufactured cast-iron cylinder head for your engine. For that reason, we are listing both ready-to-run cast iron and aluminum cylinder heads to show you the differences of each, and that way you can make an educated decision about whether to rebuild yours, or buy new.

Conclusion

When it comes right down to it, we are not in a position to tell you whether rebuilding or buying a new set of cylinder heads is the right choice for you and your application. But, hopefully after reading this article, doing some research, and talking to your local machine shop owner, you can reach a decision that works for your engine, your needs, and especially your wallet.