I finally have my 401 back from the machine shop and it's time to assemble. After lots of cleaning, cam bearing and crank install, I am on to the pistons. I went to install the oil rings and noticed I could not get the oil ring rails to seat all the way into the piston groove. The oil ring assemblies are designed so the rails ride on tabs on the expander, which helps keep the rails tight against the cylinder walls. Before I can fully compress the rails into the groove, the expander ends butt against each other. There is more than enough back clearance in the groove for everything to fit. I dropped one rail into the cylinder to make sure they are the right size and they fit fine, with almost no gap. When I installed in the groove, I assume I would see a similar tiny gap, but I cannot compress enough as the expander is holding the rails out too far. I even took out my piston ring compressor and noted there is no way I will be able to compress the oil assembly to fit into the cylinder. I am guessing I need to reduce the diameter of the expander, but want to be sure I am thinking about this correctly. Anyone use these rings before? Am I supposed to fit the expander to the piston? If so, how is it done (remove material, bend ends)? Thanks Doug
Doug To me the ring in the bore looks like it needs the ends filed to allow more gap. I'm not sure what the Buick specification for ring clearance is but I was taught at least .003" per inch of cylinder bore diameter, so somewhere around .015". Hopefully someone with more Nailhead experienced can confirm.
Several years ago I bought an engine kit with Hastings rings, wasn't a Buick, had same problem with compression rings, very poor quality. If I remember correctly I junked them and bought another brand. I swore then that I would NEVER buy another set of Hastings rings, and I won't. Rings manufactured to fit a certain size bore should NEVER need to be filed or deburred, that is just POOR QUALITY. I have built many engines with other brands and never had an issue with fit or ring gap. Just my opinion.
Ross, I understand the gap on the rail is to tight. I believe Buick spec is .015" to .035" and the spec I have from the piston manufacturer is .015". The problem is, even if I file the rail to the correct gap I won't be able to compress it to that gap on the piston as the expander is too big. I assume I need to cut down the expander, but wanted to verify first. Unfortunately, the pistons were manufactured around the specs for these rings so I would rather not switch brands. So, nobody has assembled an engine with these before?
Either the pistons are bad, machined incorrectly or the rings are bad, take your pick. Are you really going to cut and trim all your expanders to fit? You need to try another brand ring set or another brand piston. On a stock design piston in a standard size bore (std, .010,.020,.030 etc) you should not have to cut and trim anything. The pistons are NOT manufactured to accomodate HASTING rings only.
I know with my motor I had to go .037 or.038 to get a good quality ring. I think with my ross pistons we did total seal with a turbo ring. I know my rings are file fit but we did not need to touch the scrapers. Did you ever put the piston together with the expander and the oil scraper rings in a ring compressor??
Engine was bored .020". Ring heights are 5/64 (top and second) and 3/16 (oil). The pistons are from JE and were machined with all of the rings specs (height and width) from Hastings. Something is not right and it better not be the pistons as they would be alot more expensive to replace than the rings. I am going to take another look at everything tonight and contact Hastings tomorrow to discuss what I am seeing
sounds like the expander rings are too long.... and,,,, the guys are right ,,, Hastings does not enjoy a good reputation...i would go to another brand,,, sealed power, perfect circle,,, or some such.... total seal is the best I have used.... sometimes if the bores are right you can juggle rings to custom fit.... but TxJohn is right ... rings should just fit.... and at the most you should only have to file the gaps to spec....:Brow:
I used a Hastings set in my 0.020" over 401. Install went smoothly. The Moly set was pn 2M437 020 and included the following: #327 top ring 5/32" #126 2nd ring 5/32" #860 and #732 3/16" oil rings The Chrysler 413 has the same bore as our 401. They might be easier to locate using that application.
Quick update Sent some pictures to Hastings and spoke with them on the phone. They agreed it does not look right. They are sending me another set of oil rings to test. They believe someone may have packed the box wrong. I am not sure I will ultimately use their rings, but would like to see if this resolves the issue first. I did download a catalog for sealed power rings and noticed they did not sell rings for a 401 with a moly top ring and carried nothing for a .020 overbore (I checked under the Chrysler 413 and the same was true). Hopefully, another manufacturer carries comparable rings for my application. While I am waiting for the new rings to show, I figured I would ask a somewhat related question. What spec does everyone follow when checking ring end gaps? When I spoke to Hastings on the phone they mentioned their rings are manufactured for a .012 to .022 end gap and should not need to be filed. JE Pistons provided a guideline for a naturally aspirated street car of bore x.0045 for top ring; bore x.0050 for the second ring; and .015 for the oil ring rail; that would be .019, .021 and .015 for my engine. My Buick service manual listed the spec as .010 to .020 for the top and second rings and .015 to .035 for the oil ring. They're all fairly close, but who should I follow? I checked a few rings and I will definitely be on the higher end of the ranges for the top and second rings. Thanks
430 BBB rings should be the same dia as a 401 Nail Head. BBB 430 = 4.187 Nail Head 401 = 4.187 standard bore size.o No:
Doug, I would use JE's specs if file fitting. The second ring has a little more gap and that is thought to prevent ring flutter. Perhaps the most important thing is that the gap is not too small. The rings can butt if there is a tight gap and rapid expansion (heating). Piston and cylinder wall damage will result. Larger gaps are not likely to loose much compression or burn oil unless extremely wide (IE: our supercharged application with a 3.57" bore uses a .025" top ring gap and a .027" second ring gap with no oil burn or compression loss). Cheryl
Out of the box, my Hastings set was 0.018" to 0.020" for the top ring and 0.020" to 0.022" for the second ring.:TU: I had a hard time finding the 0.020" over set....which is why I went with Hastings. The old school machine shop I used recommended them as well. For a ring compressor, I highly recommend a tapered bore installer. Summit has one that's adjustable which accommodates the 4.20" bore.
[/COLOR] Along with the 430 BBB and 401Nailheads sharing bore sizes, the 455 BBB and the 425 nailhead also share the same bore size. I believe that when I overhauled my 425 some time ago, the rings for the 430/401 and the 455/425 shared part numbers. Ed
He can try 390/401 AMC .040" over rings(4.165" standard bore),would be 4.205",within .002" of the 4.207" .020" over 401 Nail Head Buick.And don't forget the Chysler 413,with a standard bore size of 4.1875,that should offer oversize rings.And there is the standard bore size of the 455 Pontiac of 4.210",with a little filing,can get the gap perfect.:TU:
I got Grants rings, and Carmen Faso said that those are not really good. And a friend from Florida recommended me to get moly rings for the 401 +0.030 over. I was up to buy Hastings moly sprayed rings from TA, but stopped for a second. Are those really bad!?
After A quick Google search, the consensus seems to be that Hastings are a high-quality ring. You could try searching an engine-builders site such as www.speedtalk.com for more opinions. For a piston ring to work well, proper cylinder wall finish and ring installation is very important!
