NASCAR Engine Build - Cookin’ Up Some Power

While Rudy and Ryan were spending sleepless nights after work building the Southern Force race car, engine builder Charlie Long was mixing up his secret recipe for power. Rudy and Ryan chose Long because his Late Model engines are well-represented in Victory Lanes across the Southeast on Saturday nights, and they have a reputation for being durable. Long’s company, Charlie’s Automotive, builds engines for many series besides Late Model, including several drag racing classes, and NASCAR’s Craftsman Truck Series, and we considered ourselves lucky he was able to work us in. We were also fortunate Long allowed us complete access to his shop in Apex, N.C., and let us document the entire engine buildup.

We’ll be racing under the ARA sanction, and thankfully, the group made a wise decision when it came to drawing up a rule book. Basically, if you own or can build a Late Model that adheres to NASCAR’s Weekly Racing Series rules, you are also legal for the ARA. You may or may not have a few quips about NASCAR’s Late Model rule book, but engine and car builders across the country are familiar with it and used to working under its guidelines. This means that if you think you’re ready to move up to a touring series, any NASCAR Late Model engine builder can put together an ARA-legal powerplant out of his parts inventory and know how to get the most out of it without a lot of R&D expense.

The major components for our GM engine are all fairly standard pieces. We are required to use a cast-iron block and heads from the manufacturer. For more information on our Sportsman Bow Tie block that we got from GM Performance parts and how we prepped it, check out “Chip Off the Old Block” in the August 2001 issue of Circle Track.

Only a minimum amount of work is allowed to be done on the stock heads. The first step for our 23-degree heads was to cut three-angle valve seats on both the intake and exhaust ports. The angles were Long’s standard setup: 30, 45 and 65 degrees.

Compression on these engines isn’t limited, but the combustion chamber on the heads must be at least 62cc, and pistons are not allowed to extend beyond the deck of the block. Flat-top pistons, of course, are also mandated. This makes keeping the combustion chambers as tight to 62cc as possible vital to making the best compression possible.

The process used at Charlie’s Automotive to achieve this is redundant with multiple checks. Late Model engines are so restricted that three or four horsepower means a lot, and this is an easy place to lose some available power if an engine builder isn’t careful. After completing the valve job, Long will check the volume of each chamber with the valves in place, and then mill the deck of the head until the largest chamber is 62cc. That, of course, will leave him with as many as three combustion chambers per head that are too small and illegal. To correct this, valves from the offending chambers are dished on a lathe to provide the extra volume necessary. Long uses Manley’s intake valves and Ferrea’s for the exhaust side and feels he gets better durability with that combination.

Going to this much trouble is of little use if the pistons, which form the floor of the combustion chamber, aren’t as exact as the heads. Charlie’s Automotive orders custom pistons from Wiseco that allows Charlie’s to do its own machine work. After checking the total length from the crank, to the rod, to the piston, Long uses a homemade clamp to deck each piston on a milling machine to get exactly the height he wants. He also cuts his own valve pockets.

“You have to get all that you can within the rules,” he explains. “The piston can’t protrude from the block and the combustion chamber has to be a minimum 62cc, so you have to make sure everything else is right. That’s why we cut our own valve reliefs, so we know they are the right size. If you do everything just right, compression for this engine should be around 11.2:1. That’s all you can get, but if you use a piston off the shelf and the valve reliefs are too deep, you may only get 11 to one. You can’t afford to waste compression.”

The crank comes from Kings Crankshaft of Denver, N.C. Long knows the importance of making the most of such a large rotating weight and takes great pains to minimize its impact on the engine.

“We do a smooth o.d., which means we have no holes in the counterweight after balancing it,” he says. “We will cut the counterweights down until we know it is too small. To get the weight back up and get it balanced we’ll have to put some heavy metal plugs in the counterweights (the material Charlie’s Automotive uses is 90 percent tungsten and 2.2 times the density of steel). On a stock crank it’s about 2.1 inches from main o.d. to counterweight, and we’ll turn them down until they are just 1.8, so that’s a good quarter inch of rotating weight on the outside diameter we’ve gotten rid of. It also reduces the amount of counterweight exposed to oil in the wet sump engine, which helps with the power a little, too.”

ARA rules state that the engine’s stroke must be OEM Chevrolet for a 350 engine, which means 3.480 inches for our power plant. Bore is limited to .045 over stock. We ordered Oliver 6.250-inch rods to connect the crank to the pistons, and Clevite bearings to go in them. Federal-Mogul provided the main bearings.

Charlie’s brother, Robert, is the main engine builder and estimates it takes Charlie’s Automotive 120 man-hours to build a Late Model engine. Robert takes great pains while prefitting the engine to make sure that he hits all sharp edges with a file to knock off any burrs. This includes the joint between the big end of the rods and the rod caps, as well as the piston tops.

“We break all the sharp lines with a file,” Robert says. “If the big end of the rod is dead sharp and you bumped it against something, it would be easier to roll the corner up so that it wouldn’t sit flat when you bolt on the rod cap. That’s less likely to happen with a rounded corner. It’s a time-consuming process for a very small benefit, but we think it’s worth it.”

There are many other little steps like this along the way. Charlie’s Automotive has only three full-time employees, including Charlie, but it uses several part-timers, mostly college engineering students. One of their jobs is to chamfer the top of every valvespring to better fit the radius on the inside of the valvespring retainers. Robert believes it helps the springs seat better as well as improves spring life and dependability. It’s a small expense, he says, compared to dropping out of a big-money race with engine failure.

Once all the pieces are properly prepared, engine assembly is straightforward. Robert triple-checks piston height with a micrometer and valve clearance with engine builders’ putty. Charlie wants .032 inch between the piston top at top dead center and the bottom of the head. Because Robert knows the head gasket thickness is between .021 and .022 inches, he checks to make sure the piston fully extended sits just .010 to .011 below the deck of the block. All fasteners were torqued to manufacturers’ specs.

Once the engine was together, it went through a break-in process on the dyno. Charlie recommends synthetic oil because they do not run an oil cooler and synthetic has higher heat properties. We are using Valvoline’s synthetic 10W-30 weight oil in the Southern Force. With all the lubricants in place Robert began the first of three sessions on the dyno. First, the engine was run at 2,500rpm for a few minutes without the inner valvespring and with short-ratio rocker arms. Next, it was run for 30 minutes with the inner valvesprings installed. Finally, the regular rocker arms were installed, and Robert began the dyno session. Everything went smoothly, and the engine met Charlie’s benchmarks on the dyno (around 350hp, although this number can be misleading because different dynomometers and even different dyno operators can achieve quite dissimilar numbers). Of course, the real test will come when we finally get this bad boy on the track.