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Tips
Tips

moved post from ZS 1500/started new

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Tipsy

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While working on my 76 1500 midget because of some starting problems I decided to change my plugs. While I was changing my plugs I figured I would do a compression test. My dry results revealed #1@155, #2@120, #3@125 and #4@125.
I asked the question: Is one high cylinder an indication of a bad exhaust valve or are 2, 3 and 4 low? I can't find any specs that say what compression should be? Does anyone else know on a 1500?
Morris responded as follows:
I'd say #155 is about right. Low compression could be a whole slew of things. I would run some Sea Foam through the intake and see if that doesn't bring your numbers up. After that, you can squirt oil into each plug hole and see if that does not bring your numbers up. If your compression comes up after squirting oil, the problem is likely your rings. If not It's likely your valves... or a blown head gasket, which in my experience is super common on 1500s.
And so I did not yet do the Seafoam but I did 3 squirts of 30w oil in each cylinder for a wet test and the results were as follows:
#1@195, #2@190, #3@210 and #4@170
Anybody have any thoughts now?
Thanks!
Jeff
 
If you have black sooty plugs, all that carbon and soot can keep your valves and rings from sealing too. That is why I suggested SeaFoam.

While 125 isn't great, it's not an emergency. I would focus on getting your carb working right, then worry about your compression. Otherwise, you could end up having to make the same repair over and over again. I still think your problem is float related. Either, your float level is too high, trash is preventing your float from closing, or your fuel pump is too powerful and it is pushing your float open when it is closed (this is a common problem). The common solution to the last problem I mentioned is to install an inline fuel pressure regulator.
 
Hoping to get to the seafoam soon. Never done it with this type of carb before. Is it done the same as others or something different?
Thanks!
Jeff
 
Tipsy said:
And so I did not yet do the Seafoam but I did 3 squirts of 30w oil in each cylinder for a wet test and the results were as follows:
#1@195, #2@190, #3@210 and #4@170
Anybody have any thoughts now?
Thanks!
Jeff
Click to expand...

I would ask what you concider three squirts? Remember that anything you add to the cylinder will decrease it's volume and increase you compresion. If three squirts were long pulls on a triger type oil can that may be too much. Just a thought about why your number came up so much.
 
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