Budman68

Started working on the car again tonight with a friend and I need help with my results.

1 - 135
2 - 160
3 - 170
4 - 150
5 - 180
6 - 165
7 - 170
8 - 130

Looks like 1 and 8 have some type of problem. We plugged a pressurized hose to 1 and it would pressure up, then bleed of a few psi, then pressure up again. Process just repeats itself. Some of the other cylinders just slowly bleed off pressure. What's going on with it? :confused:

Smokehouse69

Buddy the only way I know of the really narrow down the cause of the leak down is to do a real leak down test, with the right setup. I've seen it done a few times by mechanics, and I know it requires some specialized gauges and equipment. Done right it should tell you if it is a the valves or rings.
But, looking at your readings I'd take a wild guess that you have some burnt exhaust valves on #1 and #8.

MotorHead

Turn it over about eight times and the pressure you see on the dial is what you go by. All cylinders will slowly bleed off pressure after you stop the test. Some of the cylinders are OK (around 180psi) others are in trouble, Sould not have more thatn 10% difference between top and low cylinders.

You can do a poor man's leak down test if you have compressed are just pumo it into the cylinders and listen where you hear it leaking out, thru the diptick or tailpipe it is the rings and thru the carb it is the valves. Note that you will still hear a little hissing even on good cylinders. :D

Brettmc

Jegs has a leakdown tester for less than $120.

http://www.jegs.com/cgi-bin/ncommerc...76&prmenbr=361

Brett :thumbs:

The Money Pit

Put a shot of oil in the low cylinders through the spark plug hole,retest the compression. If it improves most likely the rings are shot.If not valves or cam lobe.You can do a visual on the cam by watching the rockers while you crank it over.

69Rat

Quote: {Put a shot of oil in the low cylinders through the spark plug hole,retest the compression. If it improves most likely the rings are shot}

:iagree:

Also, re-adjust the rockers, and do another test just to be sure you have a good base to go by.

Budman68

Food for thought...

Cam is functioning correctly.
#3 and #5 pressurize fine with a slight leak down. (Normal)

Why would #1 pressurize for a second or two, then make a pisssss noise. Then pressurize again. It seem if it was a burnt exhaust valve, it would just bleed off without holding pressure.
:confused:

zwede

Something in your write-up makes me wonder if you are testing this correctly...

1. Take all plugs out
2. Make sure battery is in good shape.
3. Connect compression gauge to #1
4. Block throttle fully open
5. Crank engine until needle stop climbing or max 10 revolutions.

Budman68

Zwede, The only thing I didn't do is leave the throttle wide open. I will re-check tonight.

yellow 72

Leak down test is the way to go, pressurize and then just listen to where the air is going...exhaust or carb=valve crankcase=rings or piston....

Budman68

Not good new... It seem she is broke. I filled #1 up with some oil and pressure tested it again. The gauge goes up to 170 and blows by. The best reading with oil was 150 average. Reassembled the plugs and started it up. It is pulsing bad at 3000 rpms. I either fried the crank or the convertor. :eek: :sad: :sad: :sad: :sad: :sad: :sad: :sad: