Ok I have pulled the long block all the way down to a rotating assembly. I checked all of the cylinders for roundness below is what I found.

I checked parallel with crank and 90* to crank

Cyl 1 3.77/3.78
Cyl 2 3.78/3.78
Cyl 3 3.76/3.77
Cyl 4 3.79/3.78
Cyl 5 3.77/3.77
Cyl 6 3.78/3.78

All of these looked good? Not a trace of ridge at top of cylinder. Top cof cylinder measured the same as the bottom.

Here is my concern, what is the end play on the connecting rods? The worst end play is about 1/32 or about .030 this is on cylinder #4. All have a little movement but this one seems to have a little more.

Any opinions?

 

What measuring system are you using and where is the 3rd digit? If you are planning a rebuild. Out of round on a cylinder should be less then .005" for the new rings to seal right. With rounding to 2 places there is no way to tell what yours are. Heaviest wear is normally toward the bottom on the exhaust side. That is normal for all V type motors.

End play on the connecting rod? you mean the side to side play the rod has when there is no oil pressure? As long as you have clearance you should be fine. When you have oil pressure the bearing will center everything where it needs to be. If you are showing wear on those surfaces you need to check you crank for endplay. I am assuming we are talking a stock GM engine.

 

Thanks for the reply, I was hoping you would respond. You sent me the pdf on how to pull the engine from my car.

I am using Telescoping gauges and slide caliper to measure. My slide caliper does not have a 3rd digit. I am going to buy a new one today.

This engine is a long block I purchased from a salvage yard, the plan is to install new gaskets and install in my Camaro. I am just checking all clearances, I do not want to install a bad engine with new gaskets.

I have visually inspected all cylinders and journals and can't find and abnormal signs of wear. Cylinder walls still have hone marks cross hatch.

Yes this is a 3.8 Series II out of a 2004 Grand Prix GT.

Thanks again for the help

 

Telescoping gages are very tuff to use. I had them when I started, they are very sensitive to angle, the handle needs to be parallel to the center of the bore, Caliper are very sensitive to pressure, Mics would be a lot better. Long story short your measuring system will most likely have as much error in it as the motor itself. I would just check for serious scars (a sign the motor has over heated). No scars seal her back up. Checking the head for flatness is a much better use of resources.

Make sure all the rods have about the same side to side play. A tight one may indicate an issue more then a loose one. One with no play would most likely be a spun bearing.

Anytime you want to verify your measuring system write all the numbers down. Wait a few hours until you forget them. Then measure it again. Compare the two measurements. You would need to be within .001” to trust your system for a .005" accuracy. In manufacturing we do this 100 times across 10 parts with 3 different people. We call it a gage R&R.

Edit: BTW if you not planning on new rings the .005” out of round kind goes out the window. Since your original rings have been in the cylinder since day one they can easily seal with .01” or even .015” out of round because they have worn that way over time. New ring are round and come with a wear area that is used during break-in. This “wear layer” can handle about .005” of out of round. Any more than that could take months to wear in.

 

I had not planned on a rebuild or new rings. Just checking everything....all rods have some end play.

It's been about 25-30 years since I have been this deep in a car/truck engine. I am just overly cautious. The donor car was a total, so mechanical failure was not it's final demise. Just don't know how well it was treated.

The end goal is to rebuild the original engine once I do the swap.

Thanks again for the advise. I am going to button it up this weekend, paint it and move on to the swap.