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03-20-2024, 05:51 PM | #21 |
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Re: Deep knocking sound
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03-20-2024, 06:57 PM | #22 |
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Re: Deep knocking sound
I've replaced all my A's to high compression heads and don't have any knocks! All stock engines and drive at 45-55.
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03-20-2024, 08:46 PM | #23 | |
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Re: Deep knocking sound
Quote:
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03-20-2024, 09:14 PM | #24 |
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Location: Lambsburg Va
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Re: Deep knocking sound
This might help and give you a little insight to what to do
https://youtu.be/8MH3HtTnshQ?si=RGbjJ5dRa5xOqvOw |
03-21-2024, 06:07 AM | #25 |
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Re: Deep knocking sound
In my opinion, the easiest way to take up the bearings is with the engine out of the car and up side down on an engine mount. For one thing the crankshaft will be held down by gravity. The clutch can be examined at the same time and repaired if needed. After removing the flywheel and flywheel housing the crankshaft can be lifted out of the engine to examine the Babbett. It will also keep you from getting lots of engine oil in your hair.
Remember to mark the caps so that they go back into the engine in the proper location and orientation. And keep track of the shims.
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A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
03-21-2024, 06:42 AM | #26 |
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Re: Deep knocking sound
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Instead of instantly pulling the engine to adjust the main bearings - although I agree that it is much easier to do it that way - I think I would first want to know if the center main cap has broken Babbitt in it. If it does, that's what is causing the loud heavy knocking noise. If the Babbitt is broken, the engine will have to come out for sure to re-do the main bearings. If the cap Babbitt is still good, it's likely the Babbitt in the block is also o.k. Not always, but usually it's the cap Babbitt that goes bad first. Check the drained oil through a strainer for pieces of Babbitt, a sure sign that one or more bearings have gone bad. Also remove the dipper tray and check for Babbitt chunks at the bottom of the pan. On the other hand, if you cannot remove any shims or only one thin one from each side from the center cap without locking up the engine, then the Babbitt up in the block is probably cracked. The kind of noise you describe cannot be eliminated by removing only one or two thin shims from the center bearing. It sounds more serious than that. Because the noise apparently started all of a sudden, I'm betting the center bearing Babbitt is history. 'Sorry for jolt, but welcome to the world of Model A Fords. The center main bearing is the Achilles heel in the Model A engine that also affects the rear main bearing and oil leakage. Cross your fingers and pray that the cap Babbitt is not broken and that you can remove a couple shims before the engine locks up. That means you just might have fixed the problem. Otherwise, you'll have to decide whether to have the mains re-poured or convert to modern insert bearings. Those readers who are familiar with my postings on two Model A websites since the late 1990's know where I stand on THAT issue! Need I INSERT my preference here??? Marshall Last edited by Marshall V. Daut; 03-21-2024 at 07:09 AM. |
03-21-2024, 10:32 AM | #27 |
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Re: Deep knocking sound
Shims get shaved off with a razor blade. Wax holds them together most of the time.
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03-21-2024, 11:39 AM | #28 |
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Re: Deep knocking sound
I have found with the shim packs available in the last few years that I usually have to lightly heat the pack with a low frame torch in order to separate them. Normally, a razor blade worked fine in the past. But the manufacturer must be using some space age crazy glue formula now to hold the layers together. It doesn't take much heat; just enough to loosen the adhesive's grip between shims.
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03-22-2024, 07:06 AM | #29 | |
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Re: Deep knocking sound
Quote:
Is this a new problem since you installed the new head?
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03-22-2024, 11:08 AM | #30 |
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Re: Deep knocking sound
Crosscut, I tried to say the same thing in post #9, with instructions on how to find the knee in the timing curve. Ignition knocking may be the problem, but a more retarded ignition will reduce the force on the main bearings and thereby reduce a main bearing knock. The timing should be corrected first and then, if the bearing knock is still present, pull the engine.
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A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
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