Newly Rebuilt 350 Losing Power
Q. I bought a small block 350 Chevy from an ad on a local bulletin board to put in my 1970 Blazer. The motor had been rebuilt with some quality parts about five years ago, but had never been run (the seller showed me all the receipts). It had forged pistons, "pink" rods, and a Chevrolet factory performance cam package that included valvesprings. I removed the distributor and spun the oil pump with a driver and electric drill as well as following all the tips from one of your "Willie's Workbenches" some years back that I had saved on new motor start-ups.
Everything went fine, but after a week or so, the motor has developed a miss at idle, and the power seems to have been reduced even though I have never done any full-throttle runs yet. I've gone through the ignition components, and even replaced the distributor, rechecked the timing, swapped the carb for a buddy's, and checked for vacuum leaks. I even did a compression check, and the cylinders were all between 150 and 165 psi. The engine runs clean and doesn't smoke out the tailpipe or the breather.
Los Angeles, CA
A. Well, the compression pressures should be a bit closer together, but that could be attributed to the rings not totally seating yet. My guess is that you have a valvetrain problem. You didn't say what type of oil you used, or if you had added a break-in lube.
What I suggest is that you pull off a valve cover, start the engine and watch the operation of the valves and rockers. My guess is that you're going to find one or more that are not coming up as high as the rest. If so, this indicates that either a cam lobe has gone flat or you have a bent pushrod, or even one that's not properly seated in the rocker. Look closely at the valvesprings and make certain that a coil isn't broken. However, being that the motor is five years old and had never been run, I'm going to guess that at least one cam lobe has gone flat from improper lubrication. Sorry to tell you this, as it's a heck of a lot of work to change out the camshaft.
Here is where the problem lies. Some years back, the oil companies and the vehicle manufacturers got together and figured that they could meet emissions regulations and prolong catalytic converter life by taking several high-pressure additives out of the oil. Not a problem because all the new engines had roller camshafts, which did a much better job of distributing the load over the camshaft than did the old flat-tappet design. Every aftermarket cam manufacturer, as well as specialty oil producers, now offer a special break-in oil or additive designed for the "old" flat-tappet cam that will prevent this wear.
Ford AOD Tranny Tips
Q. I have an '86 Ford Bronco with a 302 EFI V-8 and an AOD tranny behind it. I burnt out the Overdrive and need to replace it. What is the difference between my transmission and an AOD from an '89 model? I can't find anything out online, so hope you can help.
Virginia Beach, VA
A. The '89 AOD will work in your '86. There are things that a trans shop can do to improve it in the form of upgrades. You can swap newer geartrain components for better gearing.
Overdrive is this transmission's weakness. There are companies that make high-performance bands and high-performance servos for it, which are a good idea.
Just like a 700R4, the AOD throttle cable adjustment is vital to this transmission's life. It is not just a kickdown cable! Do not drive around with it disconnected or broken.
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