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Addition to honing question. I just noticed that only my new top ring has the plasma-moly surface. The 2nd ring is cast iron and the third, oil ring, is SS. So do the grit recomendation stay the same? It sounds like for plasma you want in the area of a #280 grit but for the cast iron I think it is more like #200-#240. So which grit to concern myself with?
BTW my rings are Sealed Power although the box say's Speed Pro. "Piston Rings, Plasma-Moly, 4.250 in. Bore, 1/16 in., 1/16 in., 3/16 in. Thickness, 8-Cylinder, Set of 8" Thanks guys, Mike |
The top ring determines the hone finish. The vast majority of second rings are cast iron - its the right material for that position.
Sealed Power and Speed-Pro are divisions of the same corporation - Federal-Mogul. If the box says Speed-Pro - - you have Speed-Pro rings. The Speed-Pro line uses only ductile iron base material and a plasma-moly face coatings (except for the Hellfire stuff). Most standard replacement Sealed Power rings are on a cast iron base with a standard moly coating (may or may not be plasma applied depending on the manufacturing plant). Roughly 50% of Sealed Power and Speed-Pro rings are actually manufactured in Dana/Perfect Circle (soon to be Mahle) plants under contract. Quite a few Perfect Circle rings are manufactured in Federal-Mogul plants. Big business works that way. |
Mike,
If I understand correctly you are replacing a set of rings in your motor which has already seen some use on these bore's. If that is the case was the block originally bored/honed with torque plates. The reason I ask is that the torque plate in simulating the head stud/bolt loading will have given a 'true' bore which will be destroyed if you simply rehone with a rigid type stone hone and no torque plates. If this is so use a 'Flex Hone' ball type of the correct grade to impart the finish you require to the cylinder walls. This will not undo all the good work of the Torque Plates. My own personal opinion on the gapless ring sets is they make for a drier engine( less low/mid range RPM blow by-leakage) particularly in our Cobra/Gt40 types where most are not used in 'real' anger all the time. In all out racing- Nascar/Drags etc the rebuilds take place long before the wear issue starts to cause a problem & at the RPM being used in racing today ring weight/flutter are the real issue. Jac Mac |
Rings
I agree with Barry on the rings combinations. One of the most imprtant things here is t get the cylinder rund and straight with using the torque plate. The hardness of the block and the material the cylinder is made out of is very important as well. The stones you use and the amount they are used is determined by the things. Also the width of the rings and how you plan on using the engine.
We have several different ways that we hone the blocks and different stones we use on the different materials. I feel that the standard style ring is the best over all way to go and in most street/strip cases the 1/16, 1/16, 3/16 is hard to beat. We use the Mahle rings quite a bit and just about zero ring seal problems or oil usage. Good luck with your project, Keith Craft |
From this discussion on ring types, block material, honing procedures and all the related stuff, it sure looks as though I made a good decision on which book to write. I pretty much cover all that's been discussed here and all other aspects of performance engine building in The Racing Engine Builder's Handbook, plus what type of ring package--tension, material, widths, etc.--to use, affects of the different types of oiling system (wet and dry sump), Nikasil coatings, honing stones, speed, pressure and lubricants, even Total Seal Quick Seat for ring break-in. It goes on and on. The point is you must match every item discussed, even the fuel you're using. But I don't think too many Cobra owners will be using alcohol or propane, but maybe nitrous or blowers.:)
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