Tech Tips from Capp’s Hot Rods: Hot Start Issues
October 1, 2014
A problem we often hear about in the hot rod world is hot starting, or rather not starting, issues. If your Chevy engine doesn’t want to start when it’s hot, there are two things that could be causing the problem: a faulty solenoid, or poor or inadequate wiring.
To determine the culprit, start by jumping the studs on the solenoid. If your engine cranks, the solenoid isn’t the problem… so it’s probably the length, gauge or quality of the wire that runs from your ignition switch to the starter.
Your next step is to check the terminations at both the ignition switch and the starter to make sure they’re in good condition, with no fraying or deterioration. Be certain that the connectors are crimped on properly and have no visible corrosion. If they appear to be good, the next step is to examine the wire. Is the gauge proper for your application? Generally, you’ll want to have a 16 gauge wire. When it comes to wiring, it’s imperative not to cut corners. We use and recommend American Autowire’s quality high heat and abrasion resistant XLPE wiring, which withstands temperatures from -60°F to +275°F.
Next, trace the wire and look for any visible damage. Follow its path and check for any kinks and/or abrasions. This sort of damage can seriously lower the ability of the wire to carry current. The final step is to check the length to make certain it isn’t longer than necessary.
If you spot any of these issues, repair or replace using quality wire.
Of course, if you jumped the solenoid and the engine didn’t crank, your problem may just be the solenoid. Starter heat shields may help preserve your starter and solenoid, but not everyone has good results. A better solution to common solenoid issues is to add a remote Ford solenoid to control your GM solenoid. Let me explain how a solenoid operates and why the remote solenoid is a good solution…
On a GM solenoid, the winding is fed through a resistive lead to the starter through an ignition switch. This results in 12 volts being applied across the solenoid winding. As the current in the lead increases, so does the voltage drop on the lead going to the solenoid, which results in less voltage to the winding. It’s alright when the solenoid is not hot. But when the solenoid gets hot, it draws more current in the lead from the switch to the solenoid winding resulting in less voltage across the solenoid activation coil. Now the solenoid will not close the contact to the starter motor, nor will it engage the pinion gear.
With a Ford solenoid installed remotely, it solves this issue by applying a full 12 volts across the GM solenoid winding This results in proper operation and engine cranking, and solves an all too common problem with Chevy powered hot rods.
With over 40 years of combined restoration experience, Capp’s Hot Rods rebuilds and restores Model As, Deuces, ’33s and up, classic cars of all makes and models, and muscle cars. Located in Woodland Hills, California, Capp’s specializes in complete wiring services, from repairs to complete harness installations. Visit their website or call 818-974-7530 for more information, or to schedule an appointment for your classic car. You can also find the Capp’s team at the Pomona Swap Meet on Road 22, Spaces 22, 24 and 26.