Dennis Wells (Wells Racing Engines) is no stranger to the pages of this magazine. For more than 40 years he has built engines for a wide range of racing and high-performance street vehicles. Because of his combined success and longevity, we recently cornered him with some specific questions about his building experiences. There are lessons to be learned from what follows.

What's the most frequent issue you face when a customer's engine doesn't perform up to his expectations?

Well, most of the time it's generally not the engine but the tune-up that's been applied to it. Obviously, conditions like atmospheric pressure and temperature can change from the dyno to the track or the car isn't handling properly. Like if it's pushing in the corners and it lugs the engine down, they don't understand that if you exit a corner 20 miles an hour lower than you need, you'll be going 20 miles an hour slower at the other end. It's incorrect to assume that just because you've got a lot of horsepower you can make up a difference like this, but you can't. It's not so much about power as it is torque and where it's produced in the rpm range. Of course, gearing can also come into play.

For example, I had a customer in here today who had just switched from alcohol to gasoline and he says the car won't come off the corners like it did. I explained to him he gave up a lot of lower rpm torque by making that change and he needed to gear the car lower. Engines are packages, and cars should obviously be geared to take the most advantage of where torque is produced. In a case like this, the lower gearing will spin the engine higher and then adequate valvespring pressure comes into play. You just have to look at the complete package.

Are there any areas of engine building that are more critical than others?

Today, I think the most critical issue is adequate valve clearance. Camshaft design and technology has changed considerably in recent years, resulting in much faster valve movement. Years past, the rule of thumb was 0.080-inch on the intakes and 0.100-inch on the exhausts. That's not true today.

I've seen instances where if the cam's ramps were rapid enough, piston-to-valve clearance needs to be as much as 0.130-inch and the valves still lightly touch the pistons. You've really got to be careful about camshaft selection and the amount of required valve clearance. This is generally not a problem on intakes as much as the exhausts, like always.

Not only do some of these cams 'pitch' the valves but cause them to bounce during closing, especially on the exhaust side. You just need to strike a balance between how much power you want or think you need compared to how much maintenance you want to do. And you can't overcome the problem with more valvespring.

The worst case I've seen was with an engine that just wouldn't make power above about 7,000 rpm. I'd been using this same combination for years with no problem. Come to find out, the pushrods were flexing. I switched from a 5/16 0.080-wall pushrod to a 3/8 0.120-wall pushrod and it was like a 50hp difference.

I guess my point is that the most critical areas aren't areas at all, but the fact that parts packages need to be treated exactly that way. In this case, you might have thought more spring pressure would've solved the problem but, in fact, it would've made it worse.

Once an engine leaves your shop, how do you deal with parts failures when the problem was caused by the customer and not the part?

If it's a loyal customer, I mean like one who's been with me for quite a while, I'll provide the labor free and maybe split the parts costs with him, depending on the situation. But if he's not going to be coming back or goes out and "bad mouths" you, that's not an attitude that makes me want to help with the repair costs. It then becomes a business decision based largely on the attitude of the customer.

Sometimes I'll fix a problem that I know was not my fault because I plan on making that money back over time with additional work for that customer. I mean one bad customer who's out there "bad-mouthing" you is just terrible. Most people don't pay much attention to comments about how good a particular motor turned out. They just remember the criticism. You get a bad name out there, even if you don't deserve it, you're in trouble. It sometimes makes good business to just fix stuff to avoid a problem like that.

You've had years of experience running chassis and engine dynomotmeters. what would you say are the benenfits of each type of testing equipment, along with any drawbacks they create?

Let me give you a current example of how these compare with each other. I just had a customer's Sport Mod car on the chassis dyno. A lot of these guys run Quadrajet carburetors and pump gas is the fuel. We're not talking about much horsepower from these motors, probably around 400 or so. Sort of a "working man's" race car class.