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At some point, I'd like to do a compression test on my 71 351c. The engine is running fine but just doing the test from a learning perspective since I've never done one prior.


So, from reading it seems the test is better when the engine is warmed. Remove the plugs and disconnect the I and S terminal on the starter solenoid. Also disconnect the coil wire at the coil. Connect a remote starter between the battery and S terminal.


The question I have is, can any damage be done to the engine while I'm cranking it over 5 or so times for 8 cylinder readings? Is oil circulating at that time and will an oil pressure be created? Since mechanical fuel pump is pumping is fuel being dumped into the cylinders during all this? Is that an issue?

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To answer some of your questions. 

With all the plugs pulled the engine turns really easy. Yes there will be oil pressure and bearings will be oiled. 

The fuel pump will be pumping but as long as you are not pushing throttle down no gas will be going into engine so the float stops more gas from going into carb. 

Just follow the instructions that come with your tester. I have not used mine in so long I do not even know where it is.

When a man is in the woods and talks and no women are there is he still wrong??:P


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If you are just going to compare cylinders to cylinders, then Not opening the carb to wide open would be ok.

I you are looking for real world numbers then the throttle needs wide open.

With the throttle closed, your numbers WILL  be lower.


for a 9.5 compression ratio 125 psi is ideal

       10.0    =  132psi

       10.5    =  139psi

       11.0    =  147psi      


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