Dear Ole Mechanic;
I recently restored a 1956 Ford pickup with a 292 cubic inch engine and a three-speed manual transmission. I did the engine rebuild myself--except for the actual machining. I had a well-known shop clean the block and head, check for cracks, bore the cylinders to match the new pistons, line-bore the main bearings, install bronze valve guides, press in new cam bearings and put in new core support (freeze) plugs. Things went together nicely. I even remembered your column about the unusual cam timing chain set up to get the cam in time with the crankshaft. When I first fired it up it ran beautiful. As I got a few miles on it, the lifters started to make a tapping noise. I pulled the rocker covers and found that the valve clearances were too loose--all of them. Thinking that the head gaskets had squeezed down, I adjusted all of the clearances to specification and buttoned things back up. The engine ran OK, but it just didn’t seem to have the "get up and go" that it had right after the rebuild. Within a total of only 700 miles, the engine just wasn’t running right and the lifters were making loud noises again. Upon checking the clearances, I found that they were all too loose again. Way too loose. I changed the oil and stuck a magnet in the drained oil and it came out with a big lump around it. There were very fine metal particles in the oil. I called the machine shop that did the work on the engine. They said that everything was right when it left their shop, but that they would send someone out to look at things after I got the engine out and torn down. I pulled the engine and started taking it apart. When I got the cam and lifters out, they were much more worn than the original ones with 100,000 miles on them that I had taken out before the rebuild. When I called the machine shop and told them what I had found, they said that they would not bother to send anyone out because I had not followed the cam break in procedure and/or had used the wrong oil. I used the same oil that I have used in my 2008 Ford F150 pickup since it was new and it runs fine. Would you please be a mechanical expert witness if I need to take them to court because I think they installed the cam bearings wrong?
Bad Cam and Lifters
Dear Bad Cam;
You don't want me as a witness, as I and most of the restoration industry have learned that the Federal Government (be it OSHA, EPA or some other part of the alphabet stew) mandated the removal of some elements from not only gasoline but also engine oils that may or may not contribute to air pollution, water pollution, acne or sensitive-bowl-syndrome. You probably saw that lead came out of our gasoline some time ago and--more recently--most of the sulfur has been taken out of diesel fuel. This caused some concern in the diesel industry, because sulfur acts as a lubricant in the injection pump and injectors. About the same time (1989?), zinc compounds were considerably reduced in automotive engine oils. This did not affect roller lifters and cams in the newer engines like your newer F150. Also, it did not affect older vehicles with many miles on them, because minerals have thoroughly coated their lifters and cams. However, new flat tappet lifters and camshafts lack the deposits of minerals that are critical to prevent wear. They only have protection from the installation lube provided with the new camshaft, and this is only designed to protect things until the oil has a chance to circulate and protect things. Unfortunately, the oil can’t provide this protection because most of the zinc has been removed.
So much for what happened. You need to clean the inside of the engine and replace anything that was damaged by the metal particles. Get a new camshaft and set of lifters. Then to prevent another failure, use a diesel-engine oil like Shell Rotlla® or Mobil Delvac® or better yet--a true racing oil. Most good racing oils say right on the container that they contain ZDDP or Zinc Dialkyl Dithio Phosphate. ZDDP is also available for purchase as an oil additive.
To make this short, sweet and to the point, most of today’s automotive oils are not compatible with older flat tappet lifters and camshafts. If you use today’s automotive oil in older vehicles, you may be running the risk of destroying the camshaft and lifters.
For a more complete analysis of this problem go to the July/August 2007 issue of Vintage Truck© and read the Tech Tips article by Rob English entitled “The Great Oil Debate,” subtitled “Emissions vs. Additives”.
Herr Professor Nuzanbolts