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-   -   sealed power moly rings (https://classicoldsmobile.com/forums/big-blocks/32908-sealed-power-moly-rings.html)

74hurstolds March 10th, 2011 04:36 PM

sealed power moly rings
 
Does anyone know what the proper grit needed for moly rings to create the crosshatch with a flex hone brush? I thought some scoring information would be specified on the ring box or in the install information that came with them but it doesn't. I heard 180 for iron rings, or finer like 240 for plasma-moly. The scoring on the motor is visible from the previous rebuild with some wear. There is no lip at the top of the cylinder wall. I'm replacing the pistons from the old 2278p's from the mid-90's that are comparable to the current speed pro 2323 18cc dish pistons.

cutlassefi March 11th, 2011 04:46 AM

240 is fine but the crosshatch needs to be approx 120 degrees I think. That enhances rings rotation and the wall to be able to hold oil.

74hurstolds March 11th, 2011 04:15 PM

Thanks for the feedback. I was at the machine shop dropping off the rotating assembly for balancing just now and I asked my engine builder and he said 625 for moly. I think that's too smooth but he's been in the biz probably 50 years. I'm wondering if he was thinking chrome... I'm hearing 400 everywhere else like the Cheby forums. :confused: I also heard that 400 would be for the stones and 240 would be for the flex hone (like you pointed out). I'm just going to do it with a 400 grit stone hone. Seems to be the only consistency I've found, unless (hopefully) someone can chime in who's done it with a flex hone for moly fairly recently. Also 45 seems to be the most common, and I seldomly see 60 or 120 for the opposite hatch.

cutlassefi March 11th, 2011 05:51 PM

Quote:

Originally Posted by 74hurstolds (Post 260978)
Thanks for the feedback. I was at the machine shop dropping off the rotating assembly for balancing just now and I asked my engine builder and he said 625 for moly. I think that's too smooth but he's been in the biz probably 50 years. I'm wondering if he was thinking chrome... I'm hearing 400 everywhere else like the Cheby forums. :confused: I also heard that 400 would be for the stones and 240 would be for the flex hone (like you pointed out). I'm just going to do it with a 400 grit stone hone. Seems to be the only consistency I've found, unless (hopefully) someone can chime in who's done it with a flex hone for moly fairly recently. Also 45 seems to be the most common, and I seldomly see 60 or 120 for the opposite hatch.

120 is the wide angle, I'm not sure you want a 45.
For the record If your machinist thinks a 625 is the stones' grit then I think I might entertain getting another machinist, 625 is the Sunned stone number, not the grit. The 625 is actually 280 grit, see below. And normally you only run the 400 grit up and down a couple of strokes. Then most use a soft stone or brush to take off all the plateus.
http://webcache.googleusercontent.co...number&ct=clnk

And normally you'll use a 220 for a plain cast ring, and probably a 180 for chrome, anybody know why?

I used to do a lot of honing in my day.

74hurstolds March 12th, 2011 08:26 AM

Probably the part number then. I was on my way out when I asked him and he was more interested in doing it himself by saying the stones are already on the machine set to go, which I do agree with. 60/120 is what the cross hatch is looking like on the motor currently. I don't want to cut corners, but thought this would be something that wouldn't be very complicated and know the risks if it's not done correctly. I may just drop the block to him and throw it in the trunk of my beater cutlass. He's been in the biz since '69 but I've heard it all before reading hours of posts. He built a nice 350 for me 10 years ago and it was a powerful motor for many years. He's charging $275 to balance the rotating assembly, probably being taken on that as well which is why I'm researching this. Know any reputable machinists in N. Illinois?

74hurstolds March 12th, 2011 10:19 AM

I'm going to go with the 4 1/4" 400 grit flex hone...

http://www.enginehones.com/gbd414400sc.html

64Rocket March 12th, 2011 08:36 PM

Make sure you have .005 clearance on the piston to cyl wall. Even tho you are just replacing the pistons, make sure to measure the clearance.

Gene

cutlassefi March 13th, 2011 07:20 AM

If they had something around a 280 I'd get that instead. Jmo.

74hurstolds March 14th, 2011 04:16 PM

.005 is a bit much for a street motor. The manufacture calls for .001.

Also I believe 280 is too rough.

The engine will sound like 8 rattle cans and smoke.

64Rocket March 16th, 2011 03:47 PM

You can go by the spec sheet if you want. I'm just saying that all the engines I have done, going by the spec sheet have come back, they run hot, hard to start when hot, and perform bad. When tore down the piston are scuff bad and are no good to reuse for the skirt has collapse .
Just my opinion.

Gene

Texas Jim March 16th, 2011 05:33 PM

Good info, 64 Rocket. I installed my '71 455 in it's present condition. (Bought a '71 Olds 98 from my neighbor's daughter, as he had passed away and had bought the car new. Engine runs perfectly, absolutely sound, w/ 94,000 orig. miles on the car-sold the body and kept the tranny and engine.)
After I do afew things to my 'Vette this summer, I'll start the major build on my '62 Ford pick-up that's running great w/ the 455 and TH400 tranny. I jotted the .005 down in the place where it shows piston to cylinder wall clearance on my build sheet. I won't be going too awfully much past stock, but f/ sure w/ a cam, lifters, push rods and roller rockers, intake ,carb, headers and ignition. Will just get the stock heads worked allittle. The most important thing IMO is to find a VERY GOOD OLDS MACHINIST. Out of everything, this seems to be the very most important part of the engine build. I personally don't think that an Olds engine can be done right, all the way through, by just a GOOD MACHINIST. You guys on here give alot of good advice, there are a handful of you guys and you know who you are.
Thanks again f/ the info. Sincerely, Jimmy.

cutlassefi March 16th, 2011 06:32 PM

Quote:

Originally Posted by 74hurstolds (Post 261616)
.005 is a bit much for a street motor. The manufacture calls for .001.

Also I believe 280 is too rough.

The engine will sound like 8 rattle cans and smoke.

O.K I will be diplomatic, why did you even ask the question? You're rebutting all the suggestions given, so just do what you want.

At .001 it'll scuff and with 400 grit it'll take a while to seat the rings imo, but you're going to do what you want anyway so what the hell.

nonhog March 17th, 2011 10:15 AM

Quote:

Originally Posted by 74hurstolds (Post 261616)
.005 is a bit much for a street motor. The manufacture calls for .001.

Also I believe 280 is too rough.

The engine will sound like 8 rattle cans and smoke.

Took me some time to come to grips with that .005. Do want you want.
But just maybe study up on that piston to cyl. wall clearance.
I think you'll find very few going with .001.
plenty of threads here and other Olds sites.

74hurstolds March 17th, 2011 10:40 AM

Okay thanks Gene, I'll take that into consideration.

74hurstolds March 17th, 2011 11:16 AM

1 Attachment(s)
Here are my measurements. The pistons are manufactured at 4.15375 but I haven't measured each one yet.

For the graphic (measurements) A is the top, about an inch down, B middle and C close to the bottom. ooo is out of round, the x axis is parallel to the length of the motor and the y axis is along the width of the motor. In other words I am standing along side of the motor when I took these measurements with a dial bore gauge.

For the out of round calculations and taper/wear calculations reference the below link.

http://biosystems.okstate.edu/home/f...inderTaper.htm


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