What to expect from your engine

   Every new or freshened engine that leaves here is in as good of shape as it will ever be. Countless hours were spent finding the best parts and combinations that work best together. Once the parts were decided upon they are carefully machined and assembled with great detail and care. New engine parts are a thing of beauty, every piece is virgin material that is custom machined and has never been used. However after they are all carefully assembled that is where the abuse starts. Here at Driskell Enterprises we dyno test every engine before sending out the door. It is truly amazing to me how much power these parts will make and the durability that they have. Sometimes it lulls us in to thinking that nothing can go wrong because most of the time the engine will go perform all year long with little maintenance. Don’t kid yourself though, we are abusing these engines run after run and sometimes even the best designed parts can fail.
   When we see an engine back after it has ran all year it is always interesting to see what everything looks like. There are ones that come in that look almost brand new, others have some worn parts but survived, and still others are on the fringe of self destruction. This can be the same engine packages with all the same parts assembled with the same clearances by the same person. So you may ask what goes wrong. It doesn’t take to long to figure that out, just look in the mirror. Since I race I am just as guilty of abusing my engines as my customers are. Lets look at some of the things that can be done to make your investment last as long as possible.
   The life blood of your engine is the oil and it will tell you just about everything you need to know about your engine. When you go to the doctor what is the first thing they usually do, they check your blood pressure and temperature to get an idea of what’s going on. Well you engine is no different. One of the first things people as is how often do I change my oil? I can tell you that you can’t change it too often, but with the high cost of a quality racing oil you might not want to change it after every race. With conventional oil I usually say 25 to 30 runs depending on the conditions, and with synthetic oils you can go a little longer maybe 40 or so runs. But remember if you sense anything going wrong, like the oil pressure changing or the car unexpectedly slowed down the oil and filter are the first thing that should be looked at. One of the tools that is a must have is an oil filter cutter so you can see what is in the filter. When you get used to looking at the filter you will know if something is wrong because there will be more and bigger pieces of material in the filter. There will always be some very small particles or glitter in the oil, most of it comes from the valve springs and retainer wearing against one another. If you find metal in the filter it is time to stop and find where it came from before it does catastrophic engine damage. I have seen way too many people know they have something wrong with the engine in the first or second round of a race and go try to run it again. They engine will more than likely not make 6 or 7 more rounds to win the race so unless there is something to be gained by winning one more round stop and live to run another day. I suppose if you were in the final round of a National event or High dollar bracket race then maybe the risk would be worth it. When choosing oil be sure to use a high quality racing oil, not the private label cheap stuff at the parts store. There are many to choose from so be sure to consult your engine builder on their preference. When it comes to viscosity I tend to be conservative and go with a 20-50. The lighter oils such as 10-30 also work well and will make about 5 more horsepower in most applications. The ultra light oils are for class competition only. The 0 weight oils need tighter clearances and oil temps that are kept in check. In comp, pro stock, and others like that where they tow the cars and keep the oil temps down and the engines come apart every 30-40 runs then the lighter oils are worth more power. The viscosity really is about what your oil temp is going to be, the cooler oil temps can run the lower weight you can run. The problem with most super class or bracket cars or even circle track cars is that sometimes the oil temp may be 120 and in the late round when they are running back to back they may climb well in to the 250 and up range. Some of the things that affect oil temps are the clearances in the engine, filled blocks, engine diapers, ECT. The bottom line if you don’t know what your oil temp is or cant keep it the same run after run then use 20-50 and when it is cold in spring and fall maybe switch to 10-30.
   Taking the valve covers off is usually not to hard of a job and it can tell you everything you need to know about your rocker arms, lifters, and valve springs. I recommend checking them after every race; it really doesn’t take all that long. Visually inspect the valve springs for breakage and use a valve spring tester to keep track of the valve spring pressure. Check the valve lash to see if there is any problem with the lifters. This is where shaft rocker are great, the valve lash stays the same and doesn’t change much so if you find one that is .004 or .005 off then you need to check to make sure nothing is wrong. It is also much easier to check the springs since there isn’t a stud girdle to remover to be able check them. If your class doesn’t allow shaft rockers then it is very important to keep and eye on the valve lash because it is more likely to change because everything is not as stable as with the shaft rockers.
   One of the other areas to look at is the spark plugs, wires, cap and rotor. The spark plugs will tell you if everything is happy in the engine. Look for the plugs to look uniform, the tip or the ground strap is not wearing or trying to burn off. A bad plug wire or cap can cause plugs to look different. The compression ratio  and the rpm range of the engine determines what gasoline needs to be run and if the gas you are using is not doing its job it will start to hurt spark plugs before it does major damage so the plugs are important. It is almost impossible to read a used plug or even a new plug that has been driven back to the trailer, to get a good idea of what’s going on with the engine via the spark plugs you need to warm the engine, install new plugs, make the run and shut off the engine at the finish line and tow back to the trailer to remove the plugs. Then you can get a good idea of the carb jetting and the timing mark. It takes years of practice to be able to read a plug and with some of the race gas it is very hard to do so don’t be afraid to ask for help.
   The last area I am covering in this article is the carburetor. It is a very simple piece of equipment and will work great for a long time with a little maintenance. The first thing to do is keep it clean, we see a lot of engines come back for a freshen up that have the carb air bleeds plugged with something. It is a good idea to take the hood or scoop off weekly to inspect the top of the carb. The air bleeds are the small brass inserts on the top of the carb. Most aftermarket carbs have removable air bleeds and the 4150 carbs have 2 per each barrel and the 4500’s can have either 2 or 3 depending on the model. Make sure these are clean, first that there are no big pieces plugging them and if that is clear then carb cleaner needs to be sprayed through them and blown out with air. The air bleeds are very sensitive, changes as small as .002 can make a big difference in the tune up so even dirt collecting in the passages in the carb will affect the tune up so keep them clean. The linkage needs to be cleaned a lubricated with something such as WD-40. If your engine has been dynoed then your tune up should be close and only the jets would need changed for the weather conditions. The thing I see happen most often is that when it gets hot and the car slows down the racer blames the carb for being too fat. While that is true if you race in the same general altitude you should only have to lean the carb 1 jet size in the summer or maybe 2 at the very most. Think of it this way, you can go from sea level to Denver and most of the time only have to lean the carb 3 jet sizes. The mistake occurs when the weather goes from hot summer to cool fall, for some reason it is harder to remember to put the larger jets back in for the better air, I guess the car runs faster and nobody thinks to give the poor engine more fuel. This can cause damage to the engine if ran like that for very long, especially in endurance type racing. So the bottom line is keep the carb clean and don’t stray too far from the baseline tune up.

Thanks and hope this helps your racing success.
Matt Driskell