Keith Dorton is no stranger to the readers of this magazine and in numerous categories of motorsports. For 46 years, his Automotive Specialists has been a reliable and leading source for both engines and components applicable to racing. His store of experience and knowledge is both extensive and practical, so this month we'll treat you to a recent discussion with him on engine building and his perspective on how many young racers may become active on circle tracks.
Circle Track: Let's talk about specific areas in the building of what we'll call a reliable and competitive "weekend racing" engine, as you've discovered over time addressing a wide variety of these type applications. Are there certain components or systems you consider more critical than others?
Keith Dorton: The first consideration is to identify the specific application and environment in which the engine will be operated. For example, if the application is a heat race and 30-lap main event situation, how you view the requirements will be different than if it's a qualifying, practice, and 250-lap main. And actually, it's much easier today to fashion an engine for just about any application because of the broader availability of quality parts than in years past. It hasn't been very long ago when you either had a basically stock piece or a very expensive piece, but now we have a broader range of good, quality parts.
More to your question, the rotating assembly is a critical system. I think the way you should choose these parts is best accomplished by talking directly to parts manufacturers. Many of these companies have active technical services, either by phone or Internet, that can and do provide good information during the parts selection process. Once a potential customer has outlined the intended use of an engine, it's possible to get helpful advice. These are not parts you can skimp on, and there are some quality rotating assembly parts that today can be bought very reasonably.
KD: These are additional parts you don't want to skimp on. The place to start here is to identify and take advantage of the parts you're allowed to run, according to the rules. I mean, if you're able to run a good, used shaft rocker arm assembly, I'd definitely favor that instead of a new set of "floppies." Skimping in the area of the valvetrain can definitely bite you in the long run. Again, based on allowances within the rules, choosing these components can be helped considerably by talking to your choice of parts manufacturer.
CT: Turning to the topic of assembling parts, are there any particular aspects of this that need to be considered and discussed?
KD: Two things come to mind. The first is that it's critical to take all the proper measurements. Clearances, concentricity, piston-to-valve, piston-to-head are among the more important areas to consider. And I'd recommend going through these measurements more than once and writing down all the information.
It's somewhat like the "measure twice and cut once" approach, except in engine building I'd consider measuring twice to be the minimum. It's pretty tough to correct a measurement mistake once the engine is running. Once again, I'd use the parts manufacturer as a source of information because it's reasonable to think he knows more than the builder, at this point. Beyond asking about clearances, I'd also inquire about coatings, oil, and things like that.
Over time, at least in our business, we've had customers that do ask these types of questions, but they do it too late, and that can be expensive. I don't know exactly why they didn't ask sooner. Maybe they were ashamed or too proud or thought the question was too simple. But from our perspective, that shouldn't be the case. I mean, no matter how simple or crazy a customer may think his question is, that's just his opinion. Any question at all deserves a straight answer, and that's how we've always operated. Put another way, there really aren't any dumb questions.
In terms of what should be avoided during assembly, here're some things to think about. Even if parts are new, we recommend checking everything for fractures or cracks by Magnafluxing or a comparable method. Sometimes parts slip by with undetected defects, so performing these tests is just good insurance against potential damage later on. In fact, if you look at the upper-level race shops, everything is treated the same and checked to make certain a defect doesn't accidentally remain, even in a new part. It's just one quality control check after another.
Of course, there are things that you really need to make certain are acceptable. Like piston-to-valve clearance. Don't take this for granted. I recommend it be checked, by various means, more than once, as I previously mentioned.
Valve stem clearance is also critical. Especially with exhaust valve clearance, you can stick a valve and "launch" an engine real quick. Rod-to-camshaft clearance on some of the stroker-type engines falls into this category, along with crankshaft-to-oil pan clearance.
Piston-to-head clearance is another area of checking that can be done quickly and simply but also easy to overlook. In particular when we're using a domed piston, but other times as well, we check piston-to-head clearance without a head gasket.
CT: Let's step back from all this for a moment and focus on what you see in the near- and long-term future for these types of engines, particularly regarding induction systems, fuels, and that sort of thing. It's pretty clear there's a technology gap between what the OEM community is building for on-road use and where circle track racing appears to be today. And maybe beyond this, how do you view the use of renewable fuels in racing?
KD: You know, Jim, think back to when you and I first got into racing. Few of us had much money but we wanted to race. Where did we go to get our first parts? Remember? The wrecking yards. And you know what we found? Engines and parts that we could afford, or maybe trade for—that became how we built a racing engine. This was OEM equipment that we adapted to our needs. Sometimes we tried our own modifications to the cylinder heads or valve jobs, and it was all part of the learning process.
My guess right now is that this is the same landscape that young, potential circle track racers will include investigating today. As a result, they'll likely use electronic fuel injection, where rules permit, recognizing the convenience and familiarity of "tuning" these engines with a lap-top computer. I don't know how to do this and you probably don't either, but the fact remains that it's where we are today.
I also believe that these same young racers-to-become are more environmentally aware than we were back then. In fact, we're all more environmentally concerned now than then. Whether it's racetrack noise, on-track emissions, or simply the amount of fuel we use, it all seems related to the environmental impact on racing. NASCAR is addressing the issue, and I know the Circle Track G.R.E.E.N. project is going down a similar path.
Eventually, all this is probably going to happen. But I think it's a matter of what's cost effective, especially for those who don't have unlimited resources. Still, the carburetor is going to be around for a long time yet. EFI is like other electronics in that the price for using it is coming down.
CT: On the fuels issue?
KD: If we're going to get any public respect going forward, I think we ought to be considering the alternatives. Circle track racing should be thinking about changes that not only need to be made to this part of our sport but what can get it back on a track of growth.