ASK RAY By Ray Bohacz
TAP, TAP, TAP
to. I only use Sunoco Super-grade gasoline and I have also tried Lucas Octane Booster I read your column all the time and and a product called Octane Supreme to learn a lot! My 1972 350 small-block increase the octane but the engine still Chevy does not have oil at the rockers. The cam was changed last year, and now the lift- pings. Any assistance you can provide will ers are really loud. I cannot adjust them to be be greatly appreciated. quiet. The camshaft is a hydraulic-lifter type. Rick Nixon The car runs and the oil light goes out Via email when the engine is started. The car has been driven about 200 miles as-is. Could the presThat is a sweet car and I love the little 290 — a great engine that got oversure just be too low? The car ran fine before the cam change. Any suggestions? shadowed by the 343 and 390. I believe you have a few things going on Bob Holland that are easily remedied. With only 27,000 Elgin, Illinois miles, I am very confident that the engine Okay, you need to think backwards and is loaded with carbon deposits that are contributing to the pinging. The “missing” start by assigning a number to the oil pressure. To do this, temporarily install a me- when cold can be caused by a few things if it is truly misfiring. chanic’s oil pressure gauge and get a readI respectfully submit that the people you ing. The oil pressure light goes out at around brought the car to have little-to-no knowl4 to 5 psi, which is not enough to keep the engine healthy. Get a pressure reading at idle edge about an older engine with a carbureand then at 2,000 rpm. tor and breaker-point distributor. You need to find someone who does. At a minimum, you need 10 psi for every The 290 is such a simple engine, but 1,000 rpm. most younger mechanics have no idea what If you are not getting oil to the rockers, they are looking at when they pop the hood. then there is most likely little to no oil at the I do not know where you are from. If I did, I lifters, which is not good. Did you change could possibly recommend a shop. With the the lifters with the cam? Are they the same proper person that little 290 will be humheight as the ones you took out? There are many possible reasons for this ming like a sewing machine! issue. I would run the engine as little as possible — just enough to get data. ENGINE BREAK-IN Sadly, I cannot help you much through a Here’s a question that has been bothmagazine column. If you are confident that ering me for years, and no one has the oil pressure was good before the cam been able to provide me with a good answer. swap, then you need to study what went Decades ago, when engine oil formulas wrong. If you are not confident of that, then were first changed to accommodate catayou still need to see what is happening; that lytic converters, and before that became begins with a mechanical gauge oil pressure common knowledge, I fell victim to three reading. Once you have that data, reach back camshaft failures during the break-in cycle out to me. (2,000-2,500 rpm for 20-30 minutes to mate the lifters to the lobes). Once I understood why and what was KNOCKING 290 happening, compensating was possible. I recently purchased a 1969 AMC But, in the back of my mind, I’ve always Javelin with only 27,000 miles. It has wondered how it was possible for millions a 290-cu.in. engine and automatic transof cars to be produced a year, coming off mission. When I first start it, I can hear the engine misfire, but after it warms up the miss the assembly lines at one a minute, and goes away. It also pings when I accelerate. Is showing up (like my brand-new 1965 GTO) with seven miles on the odometer without a it possible that the miss and the pinging are good percentage of them having premature part of the same problem? I have taken it to camshaft failure. three different mechanics to see if they can I’m just positive those millions of engines repair the engine miss and detonation/ping didn’t get a 20–30-minute cam break-in sound as I drive it, but none have been able
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HEMMINGS MUSCLE MACHINES
during or after production! So, how did they do it? And as an aside, what is best to use for a break-in oil and/or additives these days for a fresh build of a non-roller motor? Thanks. Steve LeClair Garrison, New York
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There are a number of different things going on that impact camshaft breakin. You cannot compare a performance aftermarket camshaft with higher valve spring pressure and different metallurgy to a production-line engine. Each OE manufacturer had their own procedure, which usually included a coating on the cam and lifters before assembly, compatible metallurgy on the lobe and lifter, an engineered motor oil, and relatively low valve spring pressure. In this scenario, camshaft break-in becomes moot. Look at all of the new non-automotive engines that are produced today without a roller cam, such as in farm or construction equipment, lawn mowers, generators, and so on. You do not buy a lawn tractor and break in the cam. To answer your question, new engines for the most part do not need to go through a camshaft break-in since they apply a multitude of other procedures that someone working in his or her garage cannot.
A NUMBERS GAME
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I very much enjoy your column. I call your attention to the 1967 Corvette owner’s problem with his temp gauge (“Temperature Gauge,” HMM #226, June 2022). While there could be other causes for his low-reading temp gauge, I can tell you from past experiences with Corvettes that virtually all problems are associated with incorrect temperature sending units that screw into the intake manifold. The parts suppliers for these sending units are mostly out of touch about the correct unit. Every aftermarket supplier I have bought from swears their unit is correctly calibrated, but I’ve found this to be mostly untrue. The only correctly calibrated unit I have found is sold by Lectric Limited. The tech there explained to me that if you bench test the sender with a volt-ohm meter, a sender that has 70-76 ohms will read 220 degrees on the gauge; a sender that reads 105 ohms
