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Discussion Starter #1
I'm going to do a compression test on my 289 and have the shop manual. I have a 4 barrel carb so this section applies. In part it reads:

"set the throttle plates (primary throttle plates only on a 4 barrel carburetor) and choke plate in the wide open position"

My question is how do I set the primary throttle plate in the wide open position. Since I'm a novice the more detailed the instructions the better! I presume I will have to wire the choke plate open but have no idea regarding the throttle plate.
 

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Just put a wire on the throttle linkage temporarily while you take the compression test.

For the compression test to be meaningful you should warm the engine up first and then remove all the plugs and keep the battery charged while performing the test.
Make sure you get the same number of pulses in each cylinder - should be 5 or 6.
 

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remove all spark plugs and wire choke open, you can just push the accelerator to the floor to open it as you turn the ignition key. Like said turn the engine over the same number of revolutions on each cylinder, and right down the readings of each one. If one is low then squit some motor oil in the spark plug hole and try that one again, if it comes up then it is probably the rings, if it stays low it would be either a head gasket or bad valve spring not keeping it closed or a burnt vale allowing gases to escape.
 

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Discussion Starter #5
I did the compression test today and thanks for all the help. My results were:

L1: 100
L2: 125
L3: 120
L4: 100

R1: 105
R2: 125
R3: 125
R4: 120

L1 and L4 look low to me but I would appreciate any comments. Thanks.
 

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The ultimate pressure is not as important as the cylinder to cylinder variation, should be within 10 to 15% of each other. You vary a bit more than that. If the engine is running well and not burning oil, don't worry about it. If you want to debug further, you could put a few squirts of oil into the low cylinders and check again. this can point you to worn rings if the pressure comes up or valve leaks if it doesn't. There could be other causes as well such as scores on the cylinder walls ( the oil may help this as well ) and others.

Joel
 
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