302 compressin issues

[kevinbmx77]

I had 0 psi in cylinders one and two so i replaced both head gaskets and now cylinder 1 will only get up to 50 psi and cylinder 2 will go up to about 100+ which is good. Cylinder 1 is the issue, could it be a bad intake gasket letting air leak out as it goes in?

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[kevinbmx77]

Oh and the motor has not been started since i got it

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[martin]

did you check the valves when you had the heads off?

 

[RonD]

Yes ^^^

0 PSI is not a head gasket issue, the gap in a bad head gasket can't let out enough air to cause 0 psi

Rotate engine manually with valve covers off and see if intake valves on 1 and 2 are opening all the way, you could have worn cam.
Although bad valves is more likely.

For compression psi numbers to mean anything you need an average compression number.
What was the average for the other 6 cylinders.
With all spark plugs removed, for good crank speed, I would expect above 155psi on cold engine with 9.0:1 ratio

Intake, or exhaust, manifold gasket is not related to cylinder compression numbers

 

[Big Jim M]

Howsy Kevin

I had 0 psi in cylinders one and two so i replaced both head gaskets and now cylinder 1 will only get up to 50 psi and cylinder 2 will go up to about 100+ which is good. Cylinder 1 is the issue, could it be a bad intake gasket letting air leak out as it goes in?

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Even asking such a question tells us you know very little about what you are doing.
So start off by telling us about the engine, where and why you have it and what you will do with it if it does run.
If the engine has sat for a long while and you don't know how to do a compression test you could have NO PROBLEMS and only THINK you have them.
Big Jim

 

[kimcrwbr1]

Test the compression three times engine cold 1-8 1-8 1-8. Write down the numbers and use the high number for each cylinder. Use a fully charged battery. Do a leakdown test on the low cylinders to determine what is leaking. Find compression stroke for #1 and put it TDC with the marks. Then use your compression tester fitting and put 30psi air pressure into the cylinder. listen out the exhaust, intake and valve cover for hissing that will tell you what is leaking If you hear hissing out the valve cover it is rings. Pull the radiator cap and look for bubbles that would be head gasket or cracked head. To test the other cylinder follow the firing order and stick a long screwdriver in the spark plug hole and stop when the piston is all the way up. be careful of moving parts if the motor spins easily it may turn when you put pressure in the cylinder. Compression test tells you its leaking and the leakdown points to the problem. If you have bad rings stop the test the motor needs rebuilt or replaced.

 

[kimcrwbr1]

Oh yea I use a length of vacuum tube and stick one end in yuor ear and stick the other end in the valve cover or down one of the oil drain holes in the head same with the carb/TB.

 

[kimcrwbr1]

It may be hard finding compression stroke on #1 with no compression just stick your finger in the last number of the firing order and rotate the crank the way the engine runsclockwise and when you feel compression just keep rotating until the timing marks line up to TDC.

 

[kevinbmx77]

It may be hard finding compression stroke on #1 with no compression just stick your finger in the last number of the firing order and rotate the crank the way the engine runsclockwise and when you feel compression just keep rotating until the timing marks line up to TDC.

With my finger in the number one cylinder i can feel the air really strong trying to push back like there is more the 50 psi. Im going to buy a new presure tester since the one im using looks really old and beat. I am going to find the average of all the cylinders too

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[kevinbmx77]

Even asking such a question tells us you know very little about what you are doing.
So start off by telling us about the engine, where and why you have it and what you will do with it if it does run.
If the engine has sat for a long while and you don't know how to do a compression test you could have NO PROBLEMS and only THINK you have them.
Big Jim

Its my first time building an engine so yes i do know little about how to find where the problem may be. Its out of an f150, its been out for about 5 months and sitting on a pallet with me buying parts and replacing stuff. New cam, lifters, timing set, and mustang front mounts. No matter what cylinder i put the compression tester on air leaks right back out when i stop cranking. This motor will be going into my 94 ranger. The motor is carburated. I did the test with all spark plugs in and with all spark plugs out and same results

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[kimcrwbr1]

Get a compression tester that works

 

[Hagan]

How did you adjust the valves/pushrods? Did you get new pushrods or reuse them? Did you measure them?

 

[kevinbmx77]

Get a compression tester that works

I got one, still 50 psi, someone here said put oil in that piston and try so i did and it jumped up to 130 psi so im going to be replacing the piston rings and honing the block while im at it, ive already tore everything down to the block, crank, and cam, everything else it off

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[kevinbmx77]

How did you adjust the valves/pushrods? Did you get new pushrods or reuse them? Did you measure them?

I had a whole set of lifters pushrods and roller rockers i got from this kid off his mustang but they never worked out right so im getting new rods and using the stock rockers

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