Does this cylinder wall look normal?
Thread Starter
Joined: Dec 2004
Posts: 1,294
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From: Dallas (Richardson), TX, USA
Does this cylinder wall look normal? Hey all,
I rebuilt this motor myself about 20k miles ago, and now I've got it out to change the compression (by swapping only heads and/or head gaskets), so I'm reviewing the motor to see if there's anything wrong.
I saw in the cylinders that there was some rubbing on the inside and outside of the cylinder walls. I can't feel this when I run my finger along it, but it's pretty visible. To my recollection, it looked like this when I took it apart before and took it to the machine shop.
I just want to know if my rings are sealing. I would have done a leakdown test, but I didn't think about the fact that you need to be able to put it in gear and step on the brake to keep the pistons from moving.
I rebuilt this motor myself about 20k miles ago, and now I've got it out to change the compression (by swapping only heads and/or head gaskets), so I'm reviewing the motor to see if there's anything wrong.
I saw in the cylinders that there was some rubbing on the inside and outside of the cylinder walls. I can't feel this when I run my finger along it, but it's pretty visible. To my recollection, it looked like this when I took it apart before and took it to the machine shop.
I just want to know if my rings are sealing. I would have done a leakdown test, but I didn't think about the fact that you need to be able to put it in gear and step on the brake to keep the pistons from moving.
Last edited by Gauge; Nov 25, 2008 at 04:58 PM.
Thread Starter
Joined: Dec 2004
Posts: 1,294
Likes: 0
From: Dallas (Richardson), TX, USA
No idea. I bought the pistons, handed them to the machinist, he honed out the cylinders, I took it home and assembled it.
He told me the bore on the cylinders was 3.903", and I bought 3.903" pistons. *shrug*
Is this not normal?
He told me the bore on the cylinders was 3.903", and I bought 3.903" pistons. *shrug*
Is this not normal?
Staging Lane
Joined: Sep 2008
Posts: 66
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No it is not normal and no the rings aren't sealing. The edge of the piston has a build up of oil and the dark crescent moon spanning from it burned oil also. At the top of the cylinder wall you can see where the top ring stops (normal) but you also see where the second ring stops and this is not normal. Underneath the second ring line there are dark spots indicating just how out of round and wavy the cylinder is.
It appears as though this cylinder wasn't a .005" over or more but merely honed for a little clean up and is still a standard bore?
It appears as though this cylinder wasn't a .005" over or more but merely honed for a little clean up and is still a standard bore?
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Did you put new rings on your piston's when you installed them? If so, did you hone your cylinder walls? They should have been honed when installing new rings with a cross-hatch close to 60 degrees. Honing the cylinder walls with the correct cross-hatch also helps hold a thin film of oil.
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Verdad Gallardo Thread Starter
Joined: Dec 2004
Posts: 1,294
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From: Dallas (Richardson), TX, USA
When the engine was last rebuilt it had been stock. I bought the pistons and rods and took them to the machinist. He said he was going to hone it out .005", clean it up, polish the crank, check my tolerances, and let me assemble it. It was my first time working on engine internals, so I really wanted to do it myself. I filed the new rings and slapped it all together.
I've really had no problems with the engine to speak of, and it seems to run like a champ. The best pass it's ever made at the track was on this build, and I'm running the same cam, heads, and tune as before the rebuild. There may be something wrong with it, but it doesn't seem to be that bad. In addition, I've gotten at least 18,000 miles on this motor if not 20,000. The only problem I've had is smoke on a cold start, which I believe is a PCV issue because there's oil all over the intake ports of the heads.
So, given all this info, I think that I'm going to slap this bitch back together and put the blower on it. If it dies, it dies. I've already spent a mint on this blower and everything necessary to support it. I don't see this motor falling apart on me. It might just not run quite as well as one with rings that are sealing properly... Right?
I've really had no problems with the engine to speak of, and it seems to run like a champ. The best pass it's ever made at the track was on this build, and I'm running the same cam, heads, and tune as before the rebuild. There may be something wrong with it, but it doesn't seem to be that bad. In addition, I've gotten at least 18,000 miles on this motor if not 20,000. The only problem I've had is smoke on a cold start, which I believe is a PCV issue because there's oil all over the intake ports of the heads.
So, given all this info, I think that I'm going to slap this bitch back together and put the blower on it. If it dies, it dies. I've already spent a mint on this blower and everything necessary to support it. I don't see this motor falling apart on me. It might just not run quite as well as one with rings that are sealing properly... Right?
Only 20k on the clock... doesn't look good IMO. I have a used engine with 60k on the clock and it stills an even crosshatch all the way around in every cylinder...
By the looks of that it may also be an indication of piston side loading... If it is just one Cylinder, have it double checked for out of round or to tight of a Piston to Wall Clearance. A light hone might clean it right up.
A reputable machine shop with a tourqe plate should be able to clean that up if everything else looks ok since you said you can not feel it. Should not run you more then say $150 to put the plate on and do a light hone...
I would Bite the bullet, dissassemble the Short Block and look it over... You said this was your first build... I would also look at the bearing wear to make sure you have no other issues...
Look at this way Dis-assemble and re-assemble shouldn't cost you any thing parts wise. At the very least your machinest charges a few $$$ to do a Light hone... Mine charges $45 for a light ball hone. At the most it's say $150 for a Torque Plate Hone... At the Very Most you find more issues... But at least you will know were you stand... Just remeber to label everything and it's direction so it can go back in the same way if there are no issues...
Just My .02 Worth
By the looks of that it may also be an indication of piston side loading... If it is just one Cylinder, have it double checked for out of round or to tight of a Piston to Wall Clearance. A light hone might clean it right up.
A reputable machine shop with a tourqe plate should be able to clean that up if everything else looks ok since you said you can not feel it. Should not run you more then say $150 to put the plate on and do a light hone...
I would Bite the bullet, dissassemble the Short Block and look it over... You said this was your first build... I would also look at the bearing wear to make sure you have no other issues...
Look at this way Dis-assemble and re-assemble shouldn't cost you any thing parts wise. At the very least your machinest charges a few $$$ to do a Light hone... Mine charges $45 for a light ball hone. At the most it's say $150 for a Torque Plate Hone... At the Very Most you find more issues... But at least you will know were you stand... Just remeber to label everything and it's direction so it can go back in the same way if there are no issues...
Just My .02 Worth
who ever honed this didnt do a 60 degree thatch. with it just spiraling down the cylender like that the ring rotates on the pistion and wears it out much quicker. the scuffs are not as bad as they seam. it can get those from the piston too tight or even too loose. you must have had forged pistons put in it. they have to be run looser for intial start up becaue they expand more. i wouldnt worry about the scuffs. they are not from not having torque-plated.
