Thread: compression tester

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I was wondering how is normal compression on a compression tester? I have 120 psi on mine and was wondering if thats too low?

thanx

I don't realy understand your question. Do you mean you have 120 psi on all cyl.? Or is that on just one? If you have 120 I'd say thats very good. The more important thing is that they all read close to one another. If one is lower than the others thats cause for concern. Bad rings, valves, head gasket? A compresion gauge is a good dianogstic tool.

well its my first time using it, and i used it on 4 cylinders due to frustration of not being able to get around to headers too easily. It is 120 on each cylinder. Ive been getting fuel in the fuel pan forever and thought now that it was the rings after jetting the carb way down and checking everything else i can think of.

thank you.

The compresion is good but if your puting gas into the (oil) fuel??pan. It could still be your carb gas will got bast the rings to the pan.

but how? my last thing i can think of is an intake gasket.

Originally Posted by daveid

but how? my last thing i can think of is an intake gasket.

like cffisher said, and you need to check your fuel pump.

fuel pump is good. Its an electric with reg and is at 5psi.

Your rings are not a solid RING there is a gap in them if you are leaking gas into the cyl. it will go to the pan A bad intake gasket won't cause gas in oil pan

What kind of engine are we talking about and what carb

ok. thats true. didnt think about that. Thanks. Well ive tried like 3 different carbs now ranging from the first one that was a 1050 now down to a 750 and jetted it down like 10 jets and still have the same results. I double checked to make sure the needle and seat werent leaking and they arent. No fuel is coming from the carb at all unless the throttle is hit. There is nothing left from the old fuel pump like a diaphram or anything so im just lost now after all this. I thought it could be an intake gasket cuz of maybe it getting sucked it there.
Thanx you for your help and time

its a 454,with a Few high performance parts

Check the float valve (s) you said you have an electric fuel pump if the fuel pump runs after the engine is shut off and the float valve is not adjusted it will fill the intake with gas.

is that differant from just the float? I also took the carb off today and hooked the fuel line up and ran the fuel pump for about 30 seconds just to make sure there was no gas coming out at all.

no I don't know what carb you have some have 2 float valves. but if you checked it like you say and there was no gas coming out you've got me. Your electric fuel pump isn't going through your mechanical pump is it?

nope. has a block off plate on the block. See im stumped too. Im not a mechanic yet, but ive tried everything that everyone has told me and im still stumped too. IM affraid now too, that i need to probly tear it apart now cuz of the bearings and the fuel that has passed through them.
Thanx for the help though and trying to help me out. And the carbs are all holleys