ASK RAY

TAP, TAP, TAP

Q: I read your column all the time and learn a lot! My 1972 350 small-block Chevy does not have oil at the rockers. The cam was changed last year, and now the lifters are really loud. I cannot adjust them to be quiet. The camshaft is a hydraulic-lifter type.

The car runs and the oil light goes out when the engine is started. The car has been driven about 200 miles as-is. Could the pressure just be too low? The car ran fine before the cam change. Any suggestions?

Bob Holland

Elgin, Illinois

A: Okay, you need to think backwards and start by assigning a number to the oil pressure. To do this, temporarily install a mechanic’s oil pressure gauge and get a reading. The oil pressure light goes out at around 4 to 5 psi, which is not enough to keep the engine healthy. Get a pressure reading at idle and then at 2,000 rpm. At a minimum, you need 10 psi for every 1,000 rpm.

If you are not getting oil to the rockers, then there is most likely little to no oil at the lifters, which is not good. Did you change the lifters with the cam? Are they the same height as the ones you took out?

There are many possible reasons for this issue. I would run the engine as little as possible—just enough to get data.

Sadly, I cannot help you much through a magazine column. If you are confident that the oil pressure was good before the cam swap, then you need to study what went wrong. If you are not confident of that, then you still need to see what is happening; that begins with a mechanical gauge oil pressure reading. Once you have that data, reach back out to me.

KNOCKING 290

Q: I recently purchased a 1969 AMC Javelin with only 27,000 miles. It has a 290-cu.in. engine and automatic transmission. When I first start it, I can hear the engine misfire, but after it warms up the miss goes away. It also pings when I accelerate. Is it possible that the miss and the pinging are part of the same problem? I have taken it to three different mechanics to see if they can repair the engine miss and detonation/ping sound as I drive it, but none have been able to. I only use Sunoco Super-grade gasoline and I have also tried Lucas Octane Booster and a product called Octane Supreme to increase the octane but the engine still pings. Any assistance you can provide will be greatly appreciated.

Rick Nixon

Via email

A: That is a sweet car and I love the little 290—a great engine that got overshadowed by the 343 and 390.

I believe you have a few things going on that are easily remedied. With only 27,000 miles, I am very confident that the engine is loaded with carbon deposits that are contributing to the pinging. The “missing” when cold can be caused by a few things if it is truly misfiring.

I respectfully submit that the people you brought the car to have little-to-no knowledge about an older engine with a carburetor and breaker-point distributor. You need to find someone who does.

The 290 is such a simple engine, but most younger mechanics have no idea what they are looking at when they pop the hood. I do not know where you are from. If I did, I could possibly recommend a shop. With the proper person that little 290 will be humming like a sewing machine!

ENGINE BREAK-IN

Q: Here’s a question that has been bothering me for years, and no one has been able to provide me with a good answer.

Decades ago, when engine oil formulas were first changed to accommodate catalytic converters, and before that became common knowledge, I fell victim to three camshaft failures during the break-in cycle (2,000-2,500 rpm for 20-30 minutes to mate the lifters to the lobes).

Once I understood why and what was happening, compensating was possible. But, in the back of my mind, I’ve always wondered how it was possible for millions of cars to be produced a year, coming off the assembly lines at one a minute, and showing up (like my brand-new 1965 GTO) with seven miles on the odometer without a good percentage of them having premature camshaft failure.

I’m just positive those millions of engines didn’t get a 20–30-minute cam break-in 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

A: 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

Q: 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

will read 180 degrees on the gauge. Check with them for your application. Note also that using too much sealant on the threads of the sending unit could skew your reading. The correct part number for my ’62 Corvette is 01513321.

John Doe

Via the internet

A: Thank you for sharing the part number with the readers!

Could I, in theory, just run my good car all night connected to the dead battery instead of using the 120-volt battery charger (I won’t do this)? Is there a website you know of that addresses issues like this? I was wondering about adding a second battery in my truck, just because I have a few extras laying around and was looking for a low-buck approach to this.

Tony Stilman

Via email

GIVE ME A JUMP!

Q: I have always jump-started vehicles with dead batteries quickly, and this usually works. I have a neighbor who connects the two vehicles and then runs the good car at high idle for an hour or more, then does the startup of the dead vehicle. Is there an advantage to this? I don’t know him well enough to get empirical about this, but I have several questions about this technique.

Does the charging vehicle’s system recognize the dead condition? If so, why high idle? Would the good system just see the connection as a big battery needing charge? A: Depending on how “dead” the subject battery is, it may require the host vehicle to run at an rpm level that is higher than idle for a few minutes for the jump start to be successful.

To answer the engine speed question, output is linked to the speed that the rotor in the alternator turns. By design, at a specified rpm the output plateaus. At idle, only partial output is produced.

When you jump start another vehicle, the batteries are connected in parallel (positive to positive, negative to negative). The voltage stays the same, but the potential current (amperage) is the sum of both together. Thus, many large diesel engines have two 12-volt batteries in parallel. If each battery is 1,000 amps, then the cranking motor (the proper name for the starter) has 2,000 amps available to it. When a battery is dead, then the potential energy in amperage is very low.

Your neighbor is wasting his time running the host engine for so long, but is not hurting anything.

In simplistic terms, if you were to take the dead battery out of the vehicle and connect the jumper cables to the host battery with the engine running, you could start the engine. There is an energy drop through the battery, but it is being used as a conduit other than an energy source.

Could you install two batteries in your truck? Yes, but I do not think it is worth the effort.

Send your troublesome tech questions to: askray@hemmings.com or Ask Ray, P.O. Box 2000, Bennington, VT 05201

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