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What's Your Problem? - Tech Questions

Jeff Smith Answers Some Of Our Readers' Questions

But let's get to the meat of this issue. We wanted all the details on the '98 Tahoe 350 engine, so we called our pal Ken Casey at Burt Chevrolet in Englewood, Colorado, and discovered some interesting information. Unless you're a real animal with the throttle or haul 10,000-pound trailers all day, we think your 4L60E trans can handle the torque of a 383, and we have the perfect solution. According to Casey, GM Performance Parts has just released a brand-new version of the now-famous HT 383 complete engine that is a direct bolt-in for your vehicle. The long-block comes with the same camshaft as the HT 383 short-block that's available but also comes with the iron Vortec heads that will bolt up to your existing port fuel-injection-induction system. In addition, the new HT 383 long-block comes with a water pump, flexplate, balancer, and brand-new distributor and plug wires. All you do is add your existing intake and fuel-delivery system, oil and spark plugs, and you're done!

The part number for this package is 17800393, and the Burt Chevrolet price is $4,295. Keep in mind this is a brand-new motor from Chevrolet that has a very good warranty. Plus, according to Casey, this engine package does not require a recalibration of the factory fuel curve. This is mainly because the '98 5.7 port fuel-injected engines used a mass airflow sensor (MAF) that reads the increased airflow and will automatically compensate (within a reasonable range) for the additional airflow with the stock injectors. Based on our experience with TBI 5.7 engines, it would be a good idea to check your existing fuel pressure to ensure it is on the good side of the factory specs. A new fuel filter would also help this situation. This will ensure the fuel injectors have sufficient fuel pressure.

Based on this information, you have a second alternative. You could opt for the HT 383 short-block, or what GM calls a partial engine. This comes without a camshaft or chain but does come with a balancer and flexplate (PN 12499106). GM's list price is $4,415, but call Burt for its price. You could add the HT 383 stock hydraulic roller camshaft (PN 14097395) and all the other parts, but you might also end up right back at the price for the complete engine very quickly even without buying new heads. Then you could sell your original 350 Vortec engine to some young car crafter for a couple hundred dollars, and he'd have the basis for a budget 383 configured for a one-piece rear main seal and roller cam and be on his way to a great street engine. That way, everybody wins.

We'd also go for a much better exhaust system downstream of your dual-cat system to help engine breathing. After-cat systems tend to be underrated, but most systems will reduce backpressure even after the catalytic converters, which will improve not only top-end power but will also be noticeable in terms of part-throttle torque.

We also have some ideas on a bunch of inexpensive upgrades for your 700-R4 or 4L60E transmission to make it more durable using GM components. GM has come up with a series of better parts that create what it's now calling the 4L65E, including a stronger sun-shell housing with a bearing instead of a bushing that solves a nagging cracking problem. The combination of an upgraded 4L60E with your 383 should be very durable. That's what we would do.

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