Chevrolet Repair: starting probs on my 79 corvette, stock exhaust manifold, stock gm

Question
hey barry
i have a 1979 vette that i just put a big 350 ho crate engine in, and i have a strange problem. sometimes after running for an hour or so it wont start. no clicking of the soleniod (starter is brand new and has been replaced once already). i wrapped the starter with a heat shield thinking it might be getting too hot with the new bigger engine and using the stock exhaust manifold. no luck. if i let the car sit for a few hours it starts right up, i even changed the ignition switch on the steering column thinking that may have been bad, but the problem still remains. when it wont start the voltmeter shows it pulling juice, but not as much as when it finally will start. the only thing i havent replaced is the battery. any ideas? by the way, this problem existed before the new engine was put in, with the same battery

Answer
Make sure ALL connections from batt. to ignition switch, then to "S" side of solenoid is clean and tight. Most of the times, I find faulty/failing conections at horn relay, and bad wires from main power wire to switch. Many times it's a simple wiring problem of the solenoid (purple) wire, either corroded, smashed, exposed, and routed incorrectly!! I run headers, some plated some not, and yet to have a single problem with starters whatsoever!! No wraps, just using the stock GM parts, and routing!!! Also, Think about the wrap. It holds heat in!!!! Also, Ground is extremely important, especially in a'vette. Ground straps should be clean and tight, and make sure the ones to engine to body, and engine to frame are intact!!! A quick check, put test light on the "S" side of solenoid, then have someone turn it to "start", the light should be VERY bright!! If not, either a voltage drop, or poor connection, Good Luck!