From http://craig.backfire.ca/pages/autos/boxchevy/350
Table of Contents
Background
I could never get the 350 to run right. No matter what tuning I did, it always had a rough idle when warm, which was usually bad enough to cause it to stall when in gear. I finally gave up, and decided to go for a full rebuild.
I started to take the engine apart while it was still in the car. I got it down to the short block. When the heads came off, I found something which I thought was highly indicative of what was wrong with the engine.
Corrosion on the cylinder wall, along with frost on the valves shows without doubt that there was excess moisture in the cylinder.
My first thought when seeing the frost and rust was that the cylinder wall or the head was cracked. I brought both heads to a machine shop to have them inspected for cracks and valve guide wear.
The machinist found cracks on two exhaust valve seats, and every valve guide was worn out of specification. The inspection cost $125. The price of rebuilding the heads was going to be $700, which is well over what they are worth in terms of performance. These particular heads are notorious for cracking, according to the internet.
After that, I pulled the engine and transmission from the car, and went ahead with disassembly. Using basic tools, I got the engine apart very quickly. When I took the rotating assembly apart, I found very bad wear on every crank journal, as seen below.
The main bearings and rod bearings all had dramatic wear. This explains the low oil pressure that the engine had.
Next: Rebuild Goals
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Exhaust System
