Compression test results way off 67 cutlass 330
June 14th, 2016, 06:09 PM
#41
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Eric..I meant that what I thought was a wet down test ( may not be proper ) Poured a bit of oil in the cylinders that were initially low on the first compression test ( 115 to 120..) they all shot up to 140-150 ( on the side that was lacking in compression ) As an amateur I just realized that was not the proper method. I should not have teased the cylinders with any oil at all and let the engine do its own work. Sorry.. I'm now embarrassed... I'll have to go rent the tester again and take all plugs out.... But what I do know is that it runs smooth as suede as before..Idles perfect. Except the bog on punching.
June 14th, 2016, 06:12 PM
#42
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Eric..I meant that what I thought was a wet down test ( may not be proper ) Poured a bit of oil in the cylinders that were initially low on the first compression test ( 115 to 120..) they all shot up to 140-150 ( on the side that was lacking in compression ) As an amateur I just realized that was not the proper method. I should not have teased the cylinders with any oil at all and let the engine do its own work. Sorry.. I'm now embarrassed... I'll have to go rent the tester again and take all plugs out.... But what I do know is that it runs smooth as suede as before..Idles perfect. Except the bog on punching.
June 14th, 2016, 06:43 PM
#44
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Also. the new points seem to be more challenging to set the dwell where it is supposed to be. They seem much more " cheaper" ? And I'm wondering if that's possibly the reason for the hesitation on start up and bog on acceleration...
Hey..I'ts hard to find the good points these days? Every time I order ( the picture of the points looks original.. but what I get is still the same cheap chinese points.....
Last edited by MudEye; June 14th, 2016 at 06:51 PM.
June 14th, 2016, 07:32 PM
#45
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If the new points are adjusted correctly, and hold their adjustment, then they are not the cause of your problems.
You are right, though, that new points are generally crap.
I would recommend either buying Standard Automotive Products Blue Streak points and condensers, or keeping an eye open for NOS parts.
- Eric
You are right, though, that new points are generally crap.
I would recommend either buying Standard Automotive Products Blue Streak points and condensers, or keeping an eye open for NOS parts.
- Eric
November 22nd, 2016, 04:56 PM
#46
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November 22nd, 2016, 05:25 PM
#47
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I just have to stick my 2 cents worth in. You may want to drive the vehicle a few miles to get the engine hot then check compression with it hot. You may or may not have a problem. Ask me how I know this
Good luck
Good luck
November 22nd, 2016, 05:35 PM
#48
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A leakdown test will show a holed piston, a leaky valve, a crack into the water jacket, a bad head gasket, or major ring problems (broken or over-gapped), with varying degrees of specificity.
It is not to see, in a general sense, whether your rings are sealing.
- Eric
It is not to see, in a general sense, whether your rings are sealing.
- Eric
November 22nd, 2016, 05:57 PM
#49
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Without a " leakdown test " The compression returned to " normal " after fixing the carb gas from leaking down into the cylinders....Would it be safe to say...The carb was the problem...? No more stalling...Have been driving everyday now..No issues....
November 22nd, 2016, 06:20 PM
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November 22nd, 2016, 06:48 PM
#51
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November 23rd, 2016, 04:25 PM
#52
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Thanks for reading my mind lol! Not always the best at explaining....But that's precisely what I intended to portray....
November 23rd, 2016, 04:33 PM
#53
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Sorry! I meant to say that once the carb rebuild was done and the oil barrier (between the cylinder walls and Pistons was restored, Is that what restored the compression in the 2 cylinders that were low before the carb rebuild ( as gas was leaking into them ) Because they returned to normal after the rebuild.
Thanks!
Thanks!
November 23rd, 2016, 04:34 PM
#54
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Okay.
In that case, no, it's not likely that that's what happened. Oil does provide some help in sealing when there are irregularities in the cylinder wall, but it's not relevant in this case, because we're talking about a leakdown test, and not a compression test.
Doing a compression test completely dry on a good cylinder with good rings would probably not get you a result that's very different from one with a proper film of oil, and there should be essentially no difference between a proper film of oil and a big squirt of oil in a good cylinder.
Doing a leakdown test, there should be no difference between the reading in any of the above three conditions, because if all else is well, pressure loss into the crankcase should be almost entirely through the ring gaps, and should have almost nothing to do with the ring-to-wall seal.
- Eric
In that case, no, it's not likely that that's what happened. Oil does provide some help in sealing when there are irregularities in the cylinder wall, but it's not relevant in this case, because we're talking about a leakdown test, and not a compression test.
Doing a compression test completely dry on a good cylinder with good rings would probably not get you a result that's very different from one with a proper film of oil, and there should be essentially no difference between a proper film of oil and a big squirt of oil in a good cylinder.
Doing a leakdown test, there should be no difference between the reading in any of the above three conditions, because if all else is well, pressure loss into the crankcase should be almost entirely through the ring gaps, and should have almost nothing to do with the ring-to-wall seal.
- Eric
November 23rd, 2016, 06:39 PM
#55
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Okay.
In that case, no, it's not likely that that's what happened. Oil does provide some help in sealing when there are irregularities in the cylinder wall, but it's not relevant in this case, because we're talking about a leakdown test, and not a compression test.
Doing a compression test completely dry on a good cylinder with good rings would probably not get you a result that's very different from one with a proper film of oil, and there should be essentially no difference between a proper film of oil and a big squirt of oil in a good cylinder.
Doing a leakdown test, there should be no difference between the reading in any of the above three conditions, because if all else is well, pressure loss into the crankcase should be almost entirely through the ring gaps, and should have almost nothing to do with the ring-to-wall seal.
- Eric
In that case, no, it's not likely that that's what happened. Oil does provide some help in sealing when there are irregularities in the cylinder wall, but it's not relevant in this case, because we're talking about a leakdown test, and not a compression test.
Doing a compression test completely dry on a good cylinder with good rings would probably not get you a result that's very different from one with a proper film of oil, and there should be essentially no difference between a proper film of oil and a big squirt of oil in a good cylinder.
Doing a leakdown test, there should be no difference between the reading in any of the above three conditions, because if all else is well, pressure loss into the crankcase should be almost entirely through the ring gaps, and should have almost nothing to do with the ring-to-wall seal.
- Eric
November 24th, 2016, 05:49 AM
#56
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My car ran crappy....bad gas smell,not starting...stalling.....2 cylinders were 100-115.....
Did a new carb rebuild.....No more gas smell...no stalling...
amd those cylinders that were 100-115 were now 140-150....
and compression back to normal.....
So in your opinion what could have been the problem in the first place...??
Did a new carb rebuild.....No more gas smell...no stalling...
amd those cylinders that were 100-115 were now 140-150....
and compression back to normal.....
So in your opinion what could have been the problem in the first place...??
Sounds like a needle valve stuck open, or float stuck in the up position or adjusted too high.
You also had compression readings in two cylinders of 100-115psi before and 140-150psi after.
These changes in compression are likely completely unrelated to the carburetor rebuild, and probably were due to deficiencies of measuring technique: For instance, are you certain that you had the throttle completely open while checking compression on every cylinder the first time?
- Eric
November 24th, 2016, 07:04 PM
#57
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So, you had problems including poor running, trouble starting, stalling, and a strong smell of gasoline, you rebuilt the carburetor, and all of those problems went away.
Sounds like a needle valve stuck open, or float stuck in the up position or adjusted too high.
You also had compression readings in two cylinders of 100-115psi before and 140-150psi after.
These changes in compression are likely completely unrelated to the carburetor rebuild, and probably were due to deficiencies of measuring technique: For instance, are you certain that you had the throttle completely open while checking compression on every cylinder the first time?
- Eric
Sounds like a needle valve stuck open, or float stuck in the up position or adjusted too high.
You also had compression readings in two cylinders of 100-115psi before and 140-150psi after.
These changes in compression are likely completely unrelated to the carburetor rebuild, and probably were due to deficiencies of measuring technique: For instance, are you certain that you had the throttle completely open while checking compression on every cylinder the first time?
- Eric
November 25th, 2016, 07:39 AM
#59
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I remember years ago a common problem with quadrajets was those floats that look like Styrofoam becoming saturated and causing a rich situation. As the float gets worse it slowly sinks lower. What kind of float did you have? How old was it?
I could see this causing your problem. Check your mpg and see if it goes up.
Railguy
I could see this causing your problem. Check your mpg and see if it goes up.
Railguy
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