Compression Test How-to - Pirate4x4.Com : 4x4 and Off-Road Forum

YellowIH · 03-14-2003, 10:08 AM

What are the steps for doing a compression test on a carb engine and what rates of compression shoudl you be seeing on a good motor??

Thanks.

6869704x4 · 03-14-2003, 10:51 AM

Disable the ignition.
Hold the gas wide open.
You can pull all the plugs or one at a time.
Screw the tester into the cylinder you want to check.
Turn the engine over and listen for the hits on the tester. 2 or 3 hits is OK. Just make sure you hit each one the same.
Check the reading and write it down keeping track of which cylinder you check.
The amount of pressure you get and the variation between cylinders depends on the engine. You will have to get that info yourself.
As an example my 350 hit between 175 and 180 psi. The compression is 10.5:1.

03-14-2003, 10:08 AM	#1 (permalink)
YellowIH Moderator Join Date: May 2002 Member # 12036 Location: TN Posts: 3,320	Compression Test How-to What are the steps for doing a compression test on a carb engine and what rates of compression shoudl you be seeing on a good motor?? Thanks. __________________ / SS'd 73 IH Scout II & stuff / Μολὼν λάβε / 74-75 IH 200 4x4 Truck Axles / Resident Attorney at Law

03-14-2003, 10:51 AM	#2 (permalink)
6869704x4 Registered User Join Date: Oct 2002 Member # 14584 Location: The New and improved Mexico Posts: 467	Disable the ignition. Hold the gas wide open. You can pull all the plugs or one at a time. Screw the tester into the cylinder you want to check. Turn the engine over and listen for the hits on the tester. 2 or 3 hits is OK. Just make sure you hit each one the same. Check the reading and write it down keeping track of which cylinder you check. The amount of pressure you get and the variation between cylinders depends on the engine. You will have to get that info yourself. As an example my 350 hit between 175 and 180 psi. The compression is 10.5:1. __________________ Yes my truck is environmentally friendly. It lets most of the environment in the truck with you! Last edited by 6869704x4; 03-14-2003 at 10:55 AM.

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