Piston ring help needed... Can anyone please verify that these are the correct rings for my combination? It’s an 8BA Block bored to 3-5/16” (4” Merc crank), Ross Racing aluminum 3 ring pistons (See photo) and Grant #2360 rings. Using a “pliers-style” Snap-On ring compressor, I’ve broken two middle rings and bent one oil ring on just three slugs. The rings all gap correctly for their cylinders and the specs all look right, but it ain’t happening. I should mention that the block is relieved so the top of the cylinder bore is not concentric. Any help is appreciated.
Try to keep the ring gaps away from the relieved area. Make sure the rings are oiled and use a longer compressor to keep the piston from cocking
What kind of compressor are you using? The tin sleeve type works with a relief because it is thin and can slide down the bore slightly, below the relief notch.
I understand you are braking the rings when installing them on the piston. If so the above suggestions are not on point. So I can only say be careful installing the rings. I wind them on with my fingers. Hurts but I don't break many.
Rich, It sounded to me like he was using a narrow band ring compressor and bending/ breaking the rings while fitting to the cylinders. Why else would he have mentioned the relief? Maybe to OP will clarify the situation.
I think you are right. I didn't see the part below the picture and didn't properly read the part I did see. I agree with the ring gap thought and just slow down and be careful. I also use the longer ring compressor that is suggested. But I still need to be careful and look at what is going on.
Yes, the rings were broken while inserting the pistons in the bores, not while installing the rings. When the rings were broken, I was using an older Snap-on ring compressor that's the blue steel band with the pliers. I borrowed this from a fellow flathead guru and it's seen a lot of motors, so I was concerned it was belled out at the bottom, causing the rings to pop out before going into the bores. I bought one of the cheap expando-matic one-size-fits-all compressors at NAPA and tried that with no luck. Again, the bottom oil ring pops out of the compressor and hangs on the top of the cylinder. My concern is that my rings are not correctly sized, and that I'm trying to make something fit that simply won't. If the rings are correct (which mathematically they appear to be), then is it the block relief, the ring compressor, or a combination of the two causing my woes...
Have had several relieved flatheads and have never had a problem however I was very careful and pretty tense with butt hole puckered up pretty good.
Put a ring in the cylinder and square it up. Turn a piston upside down and push the ring down a little to do this.Measure the gap between the ring ends using a feeler gauge. I would expect it to be at least .015. If it is less than that or you can't square it because there is no gap, you need to file them or replace them. With the rings installed in the piston you should be able to push the ring into the groove past the outside diameter of the piston before it bottoms out. If you can not do this they are the wrong rings for those pistons. I say again. Take your time. Be careful. Push the piston down slowly. Watch the relief area. Use a large flat bladed screwdriver to push the ring into the piston groove and give it a wack. Lots of people have installed rings in relieved Fords and you can too. Ford made relived engines for trucks at the factory and they had rings. Helpful read http://www.aa1car.com/library/ring_end_gap.htm
After doing what Rich said chamfer the bore slightly in the relief do not go far enough to get in the ring travel. 70 % of the ring is already in the bore so it shouldn't take much
True. You don't want a sharp edge to catch the ring on or to become a glow plug when the motor heats up. But the time to radius the edges was before assembly began. Be very careful about grit or anything falling down the cylinder and sticking to the rod jurnol. If you confirm these are the right rings, it is just a matter of taking your time. Maybe get a second set of hands and eyes to help you along.
It is easy to do what you just did - due to the rings wanting to "push out" in the relief area. I've put a bunch of these engines together (full race style - with full reliefs), here are a couple of the 'tricks' or techniques that I use: Ring Gaps First!: Check the two compression rings in EVERY bore - to make sure the end-clearances/gaps are correct - per the manufacturer's recommendations! This is critical and must be done before any assembly operations. 1) Relief Edge Radius: Radius the edge of the relief so as to not catch the ring and also so that you don't carve up your hands when you're putting them in/out of the bores to lubricate them (prior to assembly). This work needs to be done before you do your final SCRUB and washing of the block - as you'll create metal filings in the process. I usually put about a 1/16" radius across the relief area. 2) Ring Gap Orientation: Align your top two compression rings such that the gaps are NOT where the relief is. I mark the tops of my pistons with a black felt-tip marker (so I know where the relief is) - then I usually have my ring gaps at about 2:00 to 3:00 o-clock on one side and 9:00 to 10:00 o-clock on the other side. 3) Wooden Paint Stir Stick: I don't try to get the ring compressor to go down into the bore - when it does that, I seem to get more bind and other drama. As I'm putting the piston/rod assembly into a bore, I first tap the top of the ring compressor with a rubber hammer such that it seats against the deck all the way around (except there will obviously be a gap in the relief area). Then I gently tap the crown of the piston until the oil rings pop-out into the relief area (usually they do), then I use a wooden paint stirring stick to push the rings back into the piston as I tap on the top of the piston. You'll soon get the hang of it and find that it is easy to coax them past the relief . . . then continue to tap the top of the piston . . . watching for the middle and top compression rings in the same manner. If they pop-out into the relief, push them back in with the wooden stick (even if you have to tap on the end of the stick to coax the ring back in). This technique works really well and you won't damage the rings or the pistons (due to the wooden paint stick). 4) Examples on the HAMB: This link contains a LOT of information on building/assembling a flathead (I documented all the details): https://www.jalopyjournal.com/forum...iolet-hot-1941-42-merc-flathead-build.862832/ This link into a page shows the 'paint stick' method in usage: https://www.jalopyjournal.com/forum...hot-1941-42-merc-flathead-build.862832/page-9 See post # 257. If you continue to have drama, feel free to PM me - be happy to help out my fellow flathead friends! B&S
Thanks guys for all the replies. I'm pretty confident that the issue is not with the rings but the installer (me) and the relief. I'm going to contact Ross in the morning and verify the rings, then proceed as directed above. The paint stick is the trick, I'm sure. I'm not going to grind on the block at this point to put the radius on the relief if I don't have to, as the block is "prepped" and the crank is in, etc. Thanks again!
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