I picked up a set of cp stock 75mm bore pistons for a d16. The block was measured at exactly 75mm with a bore gauge. The top ring gap should be .019 but they are measing .023 straight out the box. I checked them in another stock block I have and came up with the same thing. Is .023 too much gap on the top ring? Any suggestions on what to do? Possibly try another set of rings? Thanks

 

I had the same damn problem with CP rings. https://honda-tech.com/zerothread?id=1866030

All my 2nd rings were huge out of the box. They told me the rings were still "within" their tolerance,, which must be like +/- 1 inch. So I spent an extra $100 on a new ring set and that set was fine but they still would not refund my money. Im leading the new bandwagon for '07. CP

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">I had the same damn problem with CP rings. https://honda-tech.com/zerothread?id=1866030
</TD></TR></TABLE>

x2, but mine were still within spec...lucky me

 

Yeah mine were on the loose end of their conservative spec too. But still not what it should unfiled. Your rings will be OK on a boosted motor but would be far too loose on a NA motor.

 

I have CP's as well and emailed CP (Darius) for ring gap recommendation. He replied back with these specs:

For 75mm, bore the block exactly to 2.953".
.018 top, .022 second. Nothing on the oil ring.

Hope that helps.

 

We have built lots of motors out of our shop with most of them using CP's and have yet to have 1 problem. Like I stated, since it sounds like there could be an issue, send me the rings and I can replace them for you if they don't measure up.


Modified by ninesecrx at 2:36 PM 2/23/2007

 

taking care of buis.^

 

I got the rings and measured them up with Darius at CP. They checked out perfect. There is a variance that is allowable with the rings when they come. All are either runnable as is or will be under size of course. Top ring will always fall between .0059-.0137 and the middle ring is always going to be between .0137-.0216

 

The ring gap specs. provided by the pistion manufacture are only the min. you can run without problems. You will be fine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by realtime858 &raquo;</TD></TR><TR><TD CLASS="quote">The ring gap specs. provided by the pistion manufacture are only the min. you can run without problems. You will be fine.</TD></TR></TABLE>

I'll actually be going with wiseco's since i tried a set of them and they spec out perfect. Seems like alot of people have had problems with the cp rings from the pm's I have recieved after this post. You may be able to run larger gaps but I would rather not have additional blow by. Runable and fitting perfect are two differnt things.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wantasol &raquo;</TD></TR><TR><TD CLASS="quote">

I'll actually be going with wiseco's since i tried a set of them and they spec out perfect. Seems like alot of people have had problems with the cp rings from the pm's I have recieved after this post. You may be able to run larger gaps but I would rather not have additional blow by. Runable and fitting perfect are two differnt things.</TD></TR></TABLE>

Either way, the rings you stated are too large are not and there is no issue with the CP rings. If you tried Wiseco rings and they came in smaller, that may be true. But that still does not mean it is the issue. The problem is these pistons are a 75mm which you are installing on a block that has already been run. It is very unlikely that the block is exactly at 75mm still. So what happens is the ring will measure out larger because it is not in a exactly 75mm bore. With the tool above that I posted it makes a true 75mm bore and shows that the ring end gaps are well below even the smallest end gap that you would want to run.

 

Can you post the ring gaps you measured then? My block was measured by me and a local engine bulder with two different bore gauges. They both read 75mm exactly. A motor with 15-20k on it is not going to be very worn where the cylinders would be that much larger. Additionally, my set of rings were tried in another 75mm block and they gapped too large. I just think its somewhat crazy that you want 20% ($100) for swaping them out.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wantasol &raquo;</TD></TR><TR><TD CLASS="quote">Can you post the ring gaps you measured then? My block was measured by me and a local engine bulder with two different bore gauges. They both read 75mm exactly. A motor with 15-20k on it is not going to be very worn where the cylinders would be that much larger. Additionally, my set of rings were tried in another 75mm block and they gapped too large. I just think its somewhat crazy that you want 20% ($100) for swaping them out.</TD></TR></TABLE>

Picture was taken with a cell phone and I did not get up close pics of the dial indicator. I can send the pistons back with a new set of rings like promissed even though these came out fine. The 20 percent restock fee is not mine, that is what CP pistons charges.

 

Can you just tell me what ring gaps you came up with? It would be interesting to see what you got on each set of rings compared to what I got. A new set of rings may fix the problem. That has never been offered before though. I'll just give you a call or call CP if necessary.

 

Now being that I am trying to get to the bottom of your problem, I took off the shelf one of my core d series blocks. This has lots of miles on it and measured over 75mm. So I know this would be the perfect candidate to just try your rings on and see what they gap out at. If the rings are going to be too large, this block would tell us. Even though I know the rings spec out ok...I am trying to give every benefit here. On my block I have, the top ring came in at .014 clearance and the 2nd ring came in at .020. This is absolutely perfect and well with in spec. So the only thing that would be possible is that your block is over sized hence you ring gaps would be too large. Or I have 1 other idea. If you are not centering the ring in the bore, it can give you false readings as well. A real easy way to make sure this is done is by using a piston with a middle ring installed and using that to push the ring into the bore. The ring will stop when it hits the deck and the ring will be perfectly centered in the bore. But if you would like...I can take pictures of this at my shop since I have a better digi camera here. But there are the hard facts that there is NOTHING wrong with your CP rings. I have proved it in every way possible!

Here are some pics. I know how everyone likes pictures. Kinda hard to see the numbers on the feelers, but I tried. Like I was saying, its a super tight squeeze to fit in the .014. The gap held it itself.






Modified by ninesecrx at 12:11 PM 3/8/2007