[calisti]

I'm about to set the ring gaps too on my 100mm CP Pistons. I decided to do this myself so I know that it was done to the CP's specification, procedure, and orientation. Does anyone know which rings are which? Top, 2nd, oiling rings? I also noticed one of the rings has half of the ring end bent up. How does is this orientated? I bought a piston ring filer (a manual one that you have the ring up against the stops and a diamond disc with a lever you turn to grind the ring end) and a feeler gauge. I'll be setting the top ring to .026, 2nd ring to .028 and the oiling ring to .015. Do I need a piston ring compressor just to check the gap clearance in the bore or can I just compress the ring by hand and use the top of the piston to push it down into the cylinder bore? I know to deburr the ring ends so it doesn't scrape the cylinder walls. I also was told to just grind one side of the ring end since the untouched end will be perfectly 90 degrees square to the top and bottom surface of the ring. Anyone with pics helps also.

I just checked the instructions that came with the rings, so I guess I'll answer some of my own questions.

The 12 and 6'clock position would be the centerline of the wrist pin.

The top ring is the copper colored ring with a bevel on the inside. This one should have the bevel facing up and the gap located at the 8 o'clock position with 12 o'clock facing the engine front.

The second ring is black and has what they called a taper hook groove on the outside edge of the ring and this one should always face down with the gap at the 9 o'clock position.

The oiling ring consists of three rings. These rings are thinner than the top and 2nd ring. The top ring is black, the middle ring is copper colored with a hex shape going up and down throughout the diameter of the ring, the bottom ring is black also but one end has half of the end bent up. I read on another thread the bent up portion goes into one of the hex valley of the middle oiling ring.


Also when setting the gaps, should I mark each set of rings I measured in each specific cylinder bore just in case there where slight variances in bore diameter?

Let me know If I have anything wrong, although I'll also give CP a call tomorrow to verify this.

[calisti]

Well I gapped the rings today. I didn't do this on an engine stand so I just placed the block halves on a piece of cardboard in my room. I used a pen light to check my measurements since lighting in my den isn't too bright. I'm not sure how the cylinder's are numbered but I started out with front passenger side. I placed the top ring in the cylinder and with the piston pushed it down passed the first ring land gap, then measured with a .026 feeler gauge. Of course it didn't fit in there so I took it out then proceeded to place the ring end against the right stop of the manual ring filer and against the diamond wheel. I bought the Summit version model #SUM-906795 from carshopinc.com for $31.95.



I proceeded to grind one side of the ring since the untouched side is already perfectly square to the top ring surface while making sure it was getting filed evenly from side to side. I did this by applying pressure on top of the ring in two places: with my palm on top of the back of the ring against the flat surface of the filer and also on the same hand using the index finger on top of the ring close to the end I was grinding. The top ring is a harder steel so I started with 5 turns at a time the put it back in the cylinder at the same depth and checked. I know it isn't much but I didn't want to go too fast since I was dealing with thousand's. It took several times grinding and checking. Once the gauge would get into the gap although tight, that would let me know to only do 1 or more full turns on the wheel. Then when finally the gauge slipped in while still feeling a slight drag, that's when it was right.

Then I did the same with the second ring. Mike at CP said to be careful with the second ring since it's cast iron and prone to breaking if pulled apart to much. This material is alot softer too so I found that about 6-8 turns did the job to get it at .028"

I placed upper and lower oiling rings into the cylinders by lightly pushing them with the piston as deep as the oiling ring land on the piston was. Measuring with a .015" feeler gauge and noticed it didn't need any grinding. It was actually slightly larger than .0015" but Mike said .015" is the minimum gap. Then with the oiling rings there is one with one side where half of the outer edge is bent up. Mike said this goes into a groove on the upper portion of the oiling ring land that keeps the ring from spinning. The middle oiling ring with peaks and valleys hex shaped ring also do not need to touched.

After setting the gaps on the set of rings for each particular cylinder I measured I made sure to deburr the corners and edges of the ring ends so that it wouldn't score the cylinder walls and also that the ends would not catch in the ring lands with extended burrs.

I then inserted the rings into there respective ring land gaps. The top brass ring had to have the bevel on the inside edge facing up with the gap at the 7 0'clock position with 12 o'clock pointing towards the front of the motor. The second ring had to have the taper hook groove on the outer edge facing down with the gap at the 9 o'clock position. The oiling ring with the bent portion goes into the groove on the upper portion of the oiling ring land gap. Then goes the hex shaped middle oiling ring and then the bottom oiling ring with this gap at the 10 o'clock position. It takes a little wiggling and finessing to get the three oiling rings in their gap. It will and must sit in there with all the outer edges of the rings flush to each other and to the piston side ring land surface.

I marked each piston accordingly: passenger front, rear or driver's side front or rear and also to the set of rings placed in them that were measured to each particular cylinder with an arrow pointing towards the front of the motor. That arrow line is also the same line to the wrist pin centerline.

I took it upon myself to set the gaps so I know that everything was done to CP's specs and procedures. After all that I double checked the orientation of all the ring gaps and the correct orientation of the bevels and taper hook grooves.

[520]

good work man. very well thought out build.

[calisti]

Thanks, I just can't wait to get back into my car.

[Neanderthal Racing]

Originally Posted by calisti

Thanks, I just can't wait to get back into my car.

you and me both.

that is some mighty impressive work youre doing, calisti. (insert one of those bowing smiley faces here)

[Mycues1982]

Thanks for sharing, I plan on doing an engine build over the winter and this will help me. Do you have any piston pics showing the ring orientations?

[calisti]

3 oiling rings:

The top oiling ring has a half of one of the ends bent up. This bent portion goes into a round notch on the upper portion of the oiling ring land gap.
The 2nd hex shaped ring with peaks and valleys gets sandwiched between the two straight oiling rings.
The 3rd oiling ring is at the bottom of the 3 rings and the gap should be located at the 10'clock position as shown in the diagram above.

All three of these rings should be flush with each other and shouldn't protrude out beyond the ring land.

[calisti]

Picked up my heads yesterday. Tom from Portflow says these heads will flow almost as good as full ported heads due to having to bore out the throat of the seats and porting in the intake bowl area. Here are some pics showing the portwork to the core shift under the seats:





Brian Crower 272 cams installed:

Supertech black nitrided intake, inconel exhaust valves and resurfaced.

[calisti]

Diagram of ring gap orientation for CP pistons and post# 52. ^

[BM_STi]

those heads look purdy!!

[calisti]

I just talked to my builder and he just checked the crank rod journal to bearing clearances with the rod caps torqued down to Manley's spec of 45 ft/lbs. I had sent the crank with the main and rod bearings that were supposedly coated by Polydyne to the machine shop back then. I specifically requested to have .001" taken off from the existing rod journal to bearing clearances. My builder says stock rod journals to bearing clearance should be .002", he was looking for .003" clearance. Stock rod journals measure 2.47 inches and he measured 2.46 inches which is 1 thou too tight from stock. I contacted the machinist and he said he didn't measure the existing clearance even though I asked if he would and sent all the bearings to them for that reason. He says he'll send it back out to who turns his cranks.
First my builder says the bearings were taped up in a vacum seal package and didn't seemed to be opened. Which is funny because I sent the bearings out to Polydyne to get coated with the dry lubricant coating. I asked it the bearings look to have the same color surface as the piston skirts and he says they just look like stock bearings to him. I'll have to see this for my self.
Another delay.... great.
I'm glad my builder checks clearances as he said he would and doesn't assume their all right.
It's a pita but I'd rather him catch this now then have to deal with a new engine build failure after.

[calisti]

Well I just got back and the bearings were coated. So the rod journal to bearing clearance was .001". If the coatings add .0005" to each side adding up to .001" and after initial wear of the coatings goes down .00025" to each side totaling to .0005" then all they need to remove is another .0005". So after the initial wear of the coatings the rod journal to rod bearing clearance would end up at .002"

[calisti]

Well so much for the accuracy of using a plastiguage. John Edwards from Costa Mesa R & D measured the rod journals at 2.045". With more accurate tools he measured rod journal to bearing clearance .002" and a tenth. So now we can go on with the assembly.

[calisti]

Here's a pic of my pickup and the flange on the block:

[calisti]

Here are some more shots of the build: