Taking my interest a step further today and purchased an engine stethoscope and compression gauge.I'm familiarizing myself with a 1959 871 172 motor and sounds. Here are the results of my testing:
Plugs - Autolite 216's all black sooted two hand loose. Will install 437's for a hotter burn. Compression test
1: 105
2: 100
3: 100
4" 105 All jumpred to 75-80 fast then after same cranks maxed at those readings. As engine was idling I pulled plug wires one at a time to listen for a change in the clacking sound. The sound appears to be at or around 4 cylinder.
When I pulled that wire the sound did not change.
Progressed down from 3 to 1. Same result. No change in clacking sound. Upon shutting down and letting it sit for 45 minute I fired her up and she backfired/popped but briefly. Left the gas valve on. Let it run and get hot, drove it around etc. Oil Pressure warmed up: High RPMS 65
Idle 40-45 Applied stethscope: Sounds did not appear all that much different from one cylinder to the other. Applied it to valve cover on top: same. Applied at cover on side no outstanding sounds to report. But that hydraulic pump sure has a bunch of moving parts in there. Yep, a lot more noise in an engine than I ever guessed. What do you make of these above results? Added Marvel Mystery Oil after draining a quart of oil from pan. Letting it run now to see if clacking will change. Will do a complete tune-up when parts arrive and change over plugs too a hotter burn plug and readjust carb to rid the rich mixtured carbon build up. Appreciate the insights to this. Tom
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