D&D piston ring problem

[macgyverizer]

I am installing new piston rings that I bought from D&D (Haystings brand). My problem is this, I checked all ring gaps in cylinders. My results were odd. The first compression ring gaps were all over spec. Per rave the gap should be between .30mm and .50mm, mine were all over .50mm except one that was right at .50mm. WTF, did I get the wrong size rings? I checked the second compression rings and low and behold, all were in spec and only one was at the upper limit. Weird. So I checked the oil control rings and again all were in spec. I called Marc at D&D and told him my findings and asked if he thought this would be a problem. His response was that these rings were made better than OEM and would hold their shape better. He said that this size difference would not be a problem. This is my first engine build so I need some input. Is Marc right that I shouldn't be concerned? Marc is a great guy, a little odd to talk to but I trust his knowledge over mine. Common sense tells me that the first compression rings should all fall in spec if the second and oil control rings do. What do you guys think? Should I install them or not?

 

[robertf]

I just rebuilt a non rover engine and used hastings rings. The first compression ring was below minimum gap and required grinding, but the rest were a couple thousandths over the max spec.


Are you using stock pistons? If so I'd look for another set of rings.

IIRC the hastings instructions said use either .004 per " of piston diameter or the manufacturers spec, whichever is bigger

 

[macgyverizer]

The pistons are stock. What would be the detrament?

 

[ptschram]

Did you measure the bore?

Typically the only way for the ring gap to be too great is if the bore is worn oversize.

Are you squaring the rings in the bore?

 

[ptschram]

Is Marc right that I shouldn't be concerned? Marc is a great guy, a little odd to talk to but I trust his knowledge over mine. Common sense tells me that the first compression rings should all fall in spec if the second and oil control rings do. What do you guys think? Should I install them or not?

Just wait, once he decides he like you, it's worse than talking with me on the phone!

As for his knowledge, he and I argue over the stupidest pedantic topics of machining, engineering, and engine building ALL the time!:rofl:

 

[robertf]

The pistons are stock. What would be the detrament?

aftermarket pistons could be different material, but since you know that the numbers in the book were based on the material and dimensions of your pistons you should observe the upper limit.

Did you have the block honed?

 

[macgyverizer]

I have not honed the cylinders yet nor have I measured them. I do not have the means to do so, however all of the cross hatching is still their. If the cylinders were worn wouldn't all of the rings be over spec? Like I said, all of the other rings were well within spec. Marc was not concerned about the difference so should I be? We are talking about .68mm max insted of .30mm-.50mm. I did square the rings with a piston and I did them all at the same position. Just need to know how I should proceed.
On a side note, I'm not trying to question Marc's knowledge, I think he knows his shit far more than me. But, This still seems odd to me.

 

[robertf]

Those rings are out of specification for the engine. They aren't anything special that expands at a different rate that a stock ring. You would be assembling an engine that will have more blow by than it should. Return them and get a different set.

 

[macgyverizer]

I just can't see why all except the first comp rings are good.