The valvesprings used in GM's...
The valvesprings used in GM's crate engines are inexpensive stock units, so it's not surprising that they give up pressure relatively quickly. Changing them often will help keep power levels up.
Cook also recommends being very careful with your lubricants-some might say it's almost to the point of being obsessive-but it's hard to argue with an eight-win season in one of the top touring series for this class. Cook replaces the transmission oil with new B&M fluid after every 150 to 200 laps. He also refuses to simply dump the gear oil back into the quick change rearend after making gear changes.
Because gear changes happen so often, the gear oil is still good so many teams will collect the oil and pour it right back into the quick change after making a gear swap. But this is also a time when contaminants and grit can get into the oil-after all, you're usually working on the ground underneath a dirty race car chassis-so Long and Cook collect all the oil in a large bucket and strain it through a fine-mesh paint strainer back at the shop before it ever goes back into the rearend. It means you have to carry more gear oil with you to the track, but that's a price they are more than willing to pay.
Finally, Long and Cook offered a few tips for racing with a crate engine. They race with GM's 604 aluminum-headed motor, but these tips are also good for the GM iron-headed 602 motor. When it comes to the engine, Cook and Long both subscribe to the same rigorous schedule with the lubricants. To make sure the motor oil is fresh and as good as possible, it's replaced on the same schedule as the transmission-every 150 to 200 laps.
Cooling is critical with these...
Cooling is critical with these engines. Long has found that this small notch cut in the nose of his car has significantly helped keep the engine cooler. On competitive setups the nose of the car is stuck to the surface of the track for a significant portion of every lap. This small notch helps keep some measure of air flowing through the radiator even when the nose of the car is digging up dirt.
One of the reasons for this is because this engine doesn't have the best internal parts, and racing it puts a lot of stress on the entire system. The meat of the usable powerband on the 604 is normally between 6,100 and 6,400 rpm when carbureted correctly. You want to be right around this range when exiting the turn and somewhere around 6,800 rpm at the end of the straight.
But continually racing at this rpm level is very tough on the lightweight valvesprings. The hydraulic lifters help protect them a bit, but they will give up pressure and when that happens it further hurts power production. So, they are automatically replaced just like the motor oil-after every 150 to 200 laps.
"That probably sounds a bit extreme," Long says, "but the good news is that the valves are really cheap. They are nothing special and you can get them at the parts counter at just about any Chevrolet dealership, so replacing a set of springs isn't all that expensive."
The last tip when it comes to racing a crate motor is to take additional steps to make sure it stays cool. As mentioned earlier, the lower power production means this engine is always "lugging" around the track and builds heat very quickly.
A four bar system on Dirt...
A four bar system on Dirt Late Models can be confusing or intimidating to new racers because of its complexity. Long recommends finding two or three changes with bar movement that work well for you and sticking with those instead of trying to get too fancy.
Another factor that some teams don't think about is the lower rpm levels these engines run at also equates to less radiator fan speed. Now you have the combination of the engine pulling as hard as possible while the radiator fan isn't pulling as much air through the radiator as you might find with other engines. While theoretically a racer could install a smaller-diameter fan pulley or a fan with more efficient blades, Long says most racers he knows use the same KRC dress kit and almost all have the same diameter pulley.
Because of this, Long says you really have to stay up on your cooling system. Keep an eye on the radiator to make sure it stays clean so that it works as efficiently as possible. Also, use a double-pass radiator which increases the cooling potential over a cheaper single-pass radiator. And believe it or not, Long says his team will normally use two new radiators over the course of a season. And this doesn't include radiators thrown out from wreck damage. "Racing on dirt is hard on radiators," Long explains, "and every time a fin gets bent you lose just a little bit more ability to cool the engine. So sometime around mid-season you usually reach a point where you are just better off to replace the thing."
So, if you're racing crates on dirt-or are considering making the switch-don't make the mistake of thinking there is no way you can give yourself an advantage over the competition. In the long run, the smart racer will always come out on top, and with these tips for making the most of your crate-powered Dirt Late Model, you can too.