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455CI Pontiac Engine Build - What's Your Problem?

TPI Trouble:More Insights

Barry Dukes, Baltimore, MD: Terry McGean brought out some good points when advising Edman on the '89 Corvette misfire and surging problems (What's Your Problem, Mar. '06). He touched on checking the ignition system, and I'd like to elaborate a little bit. The distributor used in the '89 Vette is a unit with a separately mounted coil. GM used this type of distributor from '87 to about '95 on many of its V-6s and V-8s (including the 454). When the LT1 came out, these distributors were slowly phased out.

For the most part they are very dependable, but they are notorious for cracked reluctors and bad pickup coils. The reluctor is part of the distributor shaft, and the pickup coil is attached under the reluctor and connects to the ignition module. Whenever one or both go bad you get all kinds of problems, including hard cold and/or hot starting, steady misfire, intermittent misfire, surging, bucking, and so on. I'm a mechanic in a Chevrolet dealership, and back in those days we would get customer complaints like this on a daily basis.

The easiest way to check it out is to remove the distributor, then disassemble and inspect it. When it's on the bench, just knock out the roll pin that holds the gear to the bottom of the shaft, being careful not to lose the shims between the gear and housing. The shaft usually just pulls right out, but sometimes it's gummed up and won't easily come out. In that case, just spray a little carb cleaner onto the shaft and work it back and forth a bit; this should free it up so it will come right out. When the shaft is out, inspect the underside of the reluctor for cracks. Chances are there are a few cracks if it has some miles on it. Even if no cracks are seen, if it has a lot of miles on it, replace the shaft and the pickup coil. It's cheap insurance. The modules usually hold up pretty well, but if in doubt...By the way, I just worked on a customer's '89 IROC with a 5.7 TPI and a "hard start, hot" problem. Overhauled the distributor: problem fixed.Hope this helps.


Jim Randolph, somewhere in New Jersey: I have a few questions regarding an LS1 installation on my '65 LeMans. I have been doing some research on the swap and have found all the necessary mounts, fuel systems, and so on. Everyone says they fall right into place, but in all of the articles I have read (including the ones on your Web site), it shows them being installed with aftermarket pulleys, different A/C compressor and alternator mounts, and a different power-steering pump. Can I retain the original serpentine system, exhaust manifolds, and other goodies that come on a complete used setup? What about using the T56 trans? I have found that the shifter will be 6 inches or so more to the rear, and that just seems ridiculous. Hundreds of people do this swap every day, so could you shed some light?

Jeff Smith: Great question, Jim. Let's deal with the accessory drive on the engine first. There's no reason you can't use an existing factory accessory drive on a GEN III (LS1) engine. It turns out there are at least three different accessory drives for these engines, depending upon where the engine originated.

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