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| | | THE GOSPEL ACCORDING TO KEVIN
VALVE ADJUSTMENT
written by Ron Hedger
It’s often said that winners have a plan while losers have excuses. When we come to the topic of valve adjustment, that means that those who follow a strict regimen of checking valve lash and searching for developing problems can head off financial calamity while finishing, and likely winning, more races than their competitors. Those who don’t will be looking for a scapegoat.
“Even in a 50 lap race, you can have a spring start to go away,” says engine guru Kevin Enders. “We also see push rod failures and adjuster failures on the rocker arms. Take the valve covers off, inspect everything, run a magnet around in the oil to see if you pick up any kind of debris, then adjust the lash. Big blocks or small blocks, they all need this done after every race!”
And what about the excuses? According to Enders, it’s like baseball: three strikes and you’re out.
“They didn’t have enough time! They’re too busy racing! And my personal favorite, they didn’t understand the need for it!
“Racers have to understand that if you let the valves run loose, they’ll loosen up to the point that the camshaft becomes a hammer. It just hammers the entire valve train and you’ll break a valve, a rocker arm or a lifter. Believe me, when you knock the head off a valve, you’re facing an expensive repair. And, if you don’t finish, you certainly can’t win a race.”
With a box wrench, an allen wrench and a set of feeler gauges in hand, Enders says the only other thing you’ll need, once the valve covers are off, is 20 minutes of time, preferably without interruptions that might cause you to inadvertently skip a valve.
“We always turn the engine over until the exhaust valve just begins to open, at which point we adjust the intake valve on that cylinder. After that, we bump it over until we open the intake fully, then just as it starts to close, we check the exhaust. We do our engines cylinder by cylinder. Some guys go by the firing order, which is fine, but on the dyno we bump it over with the starter and do 1-3-5 and 7, then do 2-4-6 and 8.
“ And we always rotate in the normal direction. There’s no backing up if you go by the point you’re looking for. Just go through the cycle again. We also recommend checking the lash with the engine cold, though we alwaays supply customers with both hot and cold settings. If the engine has Jesel rocker arms, the teams have to remember that they can damage them by overtightening the nuts on the adjuster. In that situation, we recommend torqueing them to a maximum of 18-22 ft.lbs., with oil.”
While everyone develops a different touch, they should still come out with lash adjustments within .001” of each other. Still, it’s a good idea to have one person handle the job race to race, making abnormalities more obvious to the hands and eyes most familiar with that engine. Engine care is, after all, both a science and an art.
“Cam lobes don’t normally go away with roller cams but it’s a big problem with flat tappet cams, so you should be concerned if you develop excessive lash” says Enders. “With rollers, lifter failure is about the only thing that causes a lobe to go away. Rocker arms don’t give any warning, they just break, but push rod ends can get beat up. Take them out and look at them closely if the lash opens up.”
Once the clearance is checked and adjusted and the valve covers back on, Enders recommends two more basic procedures that most skip, often at great peril.
“You really need to throw a timing light on it, because that’s another problem waiting to happen. Catching erratic timing can save your engine. And a lot of racers don’t seem to want to change their oil as often as they should. Clean, high quality oil is really inexpensive compared to a repair bill on an engine.”
Another area of concern is using valve lash as a tuning aid, something that works to a point but can also be an engine killer.
“Valve lash can be a useful tuning tool but you need to know the range of lash you can use without running into problems” cautions Enders, who has seen many well-intentioned strategies harm race engines over the years. “Normally, if you loosen the lash .004”, you’ll change the duration of the cam at the valve timing point, before they open or close, by about 10 degrees. That’s enough to see a change, though it’s not necessarily something you want to do at the track. Running loose gives you more torque but less power, while running tight means giving up torque to gain a little power. You can’t hurt much going a little tighter, though you’ll give up idle smoothness, but if you go too loose, you’ll start breaking parts.”
When engines leave Ender’s Phoenix, NY shop, the valves are set and it’s ready to run. But that doesn’t mean you shouldn’t check them before firing it up.
“They’re lashed properly when they leave but we still encourage everyone to check the lash. It’s good to double check, plus the team’s engine man can work on getting the proper feel to maintain our settings. And when engines come back to us for repair, we check the settings so we can advise them if they’re too tight or too loose.
“The only thing we don’t like is for teams to get into the motor at the track. If they’re having problems, they need to either not race or get another car out of their trailer. It’s not a problem if they check inside at home but the track is not the place to get into that.”
Racing today is a bottom-line business where every dollar counts. Trading 20 minutes of shop time for increased engine longevity, lower repair bills and maximum output is a winning deal for racers in any division.
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