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January 2011 Willie's Workbench

Posted in Features on January 1, 2011 Comment (0)
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January 2011 Willie's Workbench

A buddy of mine came over the other day and wanted to know just why he was having starter problems with his mid-'80s Chevy truck with a big-block engine. He never had a problem in the winter, but on hot summer days after he shut it down, it would not crank over. He said that he had to let it cool down first, and had even resorted to pouring water over the starter to cool it down. He had swapped out the starter for a rebuilt unit that has a lifetime warranty; now he was on the second starter but was still having the same problem. He even bought a new battery and replaced all the battery cables.

This used to be a major problem-not only with trucks and not just exclusively to Chevy big-blocks, but also with performance small-blocks, especially those engines with headers. I used to own an IH pickup with a performance 392ci V-8 that exhibited the same problem, and yes, it had a Delco starter just like those other GMs.

Generally speaking, heat is the enemy of starter motors, especially the GM style due to the fact that the starter solenoid is mounted on the starter, and in most instances the exhaust system is quite close to it. There are a wide variety of different-quality "stock" starters available, and generally speaking, the "discount car parts/ lifetime warranty" units are not the best choice. There are several solutions to the problem, and we will tackle them in no particular order. In fact, all of them can be used in combination.

First, the starter itself, and starting problems: on GM starters, the solenoid is mounted directly to the starter motor. Its function is to act like a large switch to transfer power to the starter itself, as well as to engage the drive teeth on the starter to the flywheel. When the windings in both the starter and the solenoid get hot, there is a lot more resistance to electric current flow. More heat equals more resistance. The electrical contacts within the solenoid also have a tendency to wear and not make good contact.

Let's start out with the wiring. It's important that the wiring connections and the cable itself offer minimum resistance. This means it is sized properly for the length of the wire and has clean corrosion-free connections. Always remember, bigger is better when it comes to wire size.

Now, with heat being the enemy of the starter, it stands to reason we want to keep that heat away from it. There are several different types of heat shields available that either wrap around the starter (they're made from a reflective soft material) or shields that are made of metal and which stand off the starter, offering an air gap between the shield and the starter.

Actually, you can buy a stock-type starter that is listed as a heavy-duty version that was used on certain truck and high-performance cars. These use a larger solenoid, and the internals of the starter-such as the field shoes, coils and armature-are a bit different. The aftermarket, and even GM Performance Parts, has some great gear-drive permanent-magnet starters that not only offer more starter power but are considerably lighter, usually running in the 10-pound range (as compared to a stock-type starter, which weighs in at over 20 pounds).

Okay, let's go on a bit on how to make use of a Ford-type solenoid. (Oh, if you don't want to tackle locating the necessary parts to do this, Summit Racing [www.summitracing.com] has it all in kit form.) By mounting the Ford-type solenoid on the firewall, you're ensuring full amperage to both the GM solenoid and the starter. This is especially true when the current that activates the GM solenoid has to travel from the battery through the ignition switch, through the neutral safety switch and then down to the starter. There are lots of chances for flow resistance along this path. A Ford-type solenoid, which in reality is nothing more than an electromagnetic switch, connects the battery directly to the starter and takes considerably fewer amps to make work.

You're going to need a Ford-type starter solenoid-just about any one will work, up to about 1996-or an AMC/Jeep solenoid, or an AC Delco unit (p/n U939), along with two new cables. Mount the new solenoid on the firewall or the inner fender panel, making sure the mounting surface provides for a ground.

Okay, let's go on a bit on how to make use of a Ford-type solenoid. (Oh, if you don't want to tackle locating the necessary parts to do this, Summit Racing [www.summitracing.com] has it all in kit form.) By mounting the Ford-type solenoid on the firewall, you're ensuring full amperage to both the GM solenoid and the starter. This is especially true when the current that activates the GM solenoid has to travel from the battery through the ignition switch, through the neutral safety switch and then down to the starter. There are lots of chances for flow resistance along this path. A Ford-type solenoid, which in reality is nothing more than an electromagnetic switch, connects the battery directly to the starter and takes considerably fewer amps to make work.

You're going to need a Ford-type starter solenoid-just about any one will work, up to about 1996-or an AMC/Jeep solenoid, or an AC Delco unit (p/n U939), along with two new cables. Mount the new solenoid on the firewall or the inner fender panel, making sure the mounting surface provides for a ground.

With a strip of heavy copper, make a lug that connects the battery cable terminal on the starter to the "S" terminal on the starter solenoid.

Run a length of (minimum size #2) cable from one side of the firewall-mounted solenoid's large terminal to the battery's positive post.

Run a length of (minimum size #2) cable from the opposite side of the firewall-mounted solenoid's large terminal down to the starter solenoid battery connection terminal.

Move the wire that went to the "S" terminal on the starter up to the one of the small terminals on the new firewall-mounted solenoid. It may or may not be marked with an "S." You can shorten this wire if you like. This wire comes from the ignition switch (and perhaps the neutral safety switch) and is what activates the solenoid when the key is turned to Start.

Move the wire (if applicable) that went to the "R" terminal on the starter solenoid up to the other small terminal on the new firewall-mounted solenoid. Again, you can shorten this wire if you like, or you can actually leave this wire in its original location. When applicable, this wire goes to the coil, bypassing the inline resistor or resistor wire, to provide a full 12 volts to the coil for better initial start-up.

Don't worry about it if you have the wires hooked up wrong if the solenoid terminals are not marked-you'll find out soon enough if it doesn't work. Different models of remote solenoids may require you to reverse the small terminal wires. If not marked with a "S," you can easily determine which one is the start terminal by using a short jumper wire from the battery cable connection to one of the small terminals. Do this before you connect the cable from the firewall-mounted solenoid to the solenoid on the starter. Contact with the start terminal will cause the firewall-mounted solenoid to click, indicating that contact is being made.

An added advantage to using the firewall-mounted solenoid is that the battery cable connection on the solenoid makes a good location to get power for any additional accessories that you may want to mount, but remember to use a fuse in the system.

I should mention one more thing before leaving the subject of starters. You just don't bolt in a GM starter, and the same goes for those on AMC (and most other) engines. The spacing of the meshing gears has to be adjusted properly to ensure long life, both of the flywheel gear and the starter gear. You do this with shims between the starter and its mounting pad. These shims are readily available at most auto-parts stores. The first adjustment is that the end of the pinion should be about 0.060 to 0.140 inch away from the flywheel when not engaged. This can be checked with a feeler gauge. The next measurement should be the backlash between the gears when they mesh. The easiest way is to measure the clearance between the top of the pinion gear to the valley between two of the flywheel teeth. The clearance should be somewhere between 0.035 and 0.060 inch to provide the proper backlash. It's impossible to use a standard feeler gauge in this tight area, so the trick here is to use a couple of paper clips. Yep, paper clips. The standard small ones will run between 0.030 and 0.034 inch in diameter, and the bigger ones are about 0.045 inch, so if you can get the small one in and the bigger one is a tight fit, you're pretty darn close. Again, the clearance is adjusted by using the proper shims.

You will need to use some type of a prybar to force the pinion gear into meshing with the ring gear to do your measuring. I have never tried it, but I've heard of people removing the starter cable and running a small jumper wire from the battery to the solenoid "S" terminal so only the solenoid pushes the gear to engage and the motor actually doesn't turn over.

One more thing: Use the proper bolts-the ones with the knurled section between the head and the threads. This provides a tight fit for the bolts and keeps the starter from moving around.

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