Compression test procedure?

[SHOdded]

With a few parts/sensor changes, the 13+ engines can work with the 10-12s.  Waiting for a "definitive" list from a SHOforum member.
http://shoforum.com/index.php?threads/2010-sho-threw-a-rod-new-motor-required.132357/page-3#post-1457410

That slight vibration while driving might be from the PTU.  There is a TSB out for it, see if it fits what you are seeing:
http://www.revbase.com/BBBMotor/TSb/DownloadPdf?id=169301

The PTU is/should be disengaged in Park and Neutral.

 

[Spenser281]

Thanks for the heads up on the TSB.  It somewhat fits the description, but I just started noticing it about the same time as the rough idle, so I'm assuming it is attributed to the weak cylinder.  I suppose if it continues doing the same after the engine is replaced, I will dig into the PTU next.

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[sholxgt]

Just finished doing a compression test on mine.  All cylinders were between 172-178.

Looking more and more like my stutter is transmission related.

Thankfully, I will not be fighting Spenser trying to find a new short block

 

[Spenser281]

Those numbers look perfect.  Hopefully you get the shudder figured out.

As for fighting me for a short block, I'm terribly sorry to disappoint you, but I bought a used engine off of eBay and had it sent Livernois for some work.

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[SHOdded]

Looking forward to the results, Spenser!

 

[sholxgt]

Those numbers look perfect.  Hopefully you get the shudder figured out.

As for fighting me for a short block, I'm terribly sorry to disappoint you, but I bought a used engine off of eBay and had it sent Livernois for some work.

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That's exciting!  I love to see someone turn a problem into an opportunity. Can't wait to hear more as your adventure continues.

 

[Gjkrisa]

Performed a lead down test today.  Cylinder #6 is leaking air out of the oil filler tube on the valve cover.  Also getting about 60% leakage.  I checked two other cylinders just to verify I was getting it right.  Only showing about 3% leakage on them.  So since the air is coming out of the oil filler tube, that leads me to conclude that it is a broken compression ring.  Ugh.

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If it is bad rings just change the rings and maybe the piston $500 at most for parts not sure if it would be possible to do the work without pulling the engine as I am away from my car till the 8th to get a closer look at the possibility.

Also did you try the table spoon of oil to see if compression gets better?

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[Spenser281]

Performed a lead down test today.  Cylinder #6 is leaking air out of the oil filler tube on the valve cover.  Also getting about 60% leakage.  I checked two other cylinders just to verify I was getting it right.  Only showing about 3% leakage on them.  So since the air is coming out of the oil filler tube, that leads me to conclude that it is a broken compression ring.  Ugh.

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If it is bad rings just change the rings and maybe the piston $500 at most for parts not sure if it would be possible to do the work without pulling the engine as I am away from my car till the 8th to get a closer look at the possibility.

Also did you try the table spoon of oil to see if compression gets better?

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Too late for that.  I've already bought a used engine off of eBay and sent it to Livernois.  I'll most likely have them do rings and bearings.  Obviously if the cylinder is scored too bad, I may be doing a set of pistons.  My checking account will do the majority of the decision making. 

As for whether re-ringing cylinder 6 with out pulling the engine, I suppose it's possible.  But I don't think I'd want to attempt it.

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[Gjkrisa]

Have you talked to them about port polish and closed deck?

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[Gjkrisa]

I've read on the forum that port polish is not necessary but most likely the heads are a cast so there are going to be cast lines more air you can flow less restrictive the better and they have a flow bench to test how much more they can get it

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[polskifacet]

This all seems to be an exact repeat of my issue but I had a cracked head too. As for compression testing I subconsciously knew that one cyl was dead so I didnt bother turning fuel off. Car wont start when you have no plugs in it lol, they should all be out during the test.

Blaming the LMS tune goes through my head but then I think that it would never be 1 cyl getting so much heat to crack stuff. Has to be sub par quality motors?