I'm doing a stock type rebuild to a 455 and decided to go with the Keith Black 455 piston. I've had really good luck with these in some street/mild strip Chevrolet applications and just recently discovered the Buick 455 piston they offer. I like how quiet they run and the superb oil control. The 455 piston claims to yield the same compression that a 1970 stock piston would. But note the quench region and peculiar ring spacing. It seems no compromise was made with the quench because there are two different pistons to match the two different valve arrangements. Just thought I would share some pics.
Those are interesting...looks like the second compression ring and the oil ring have been moved down in the bore. Obviously those rings will run cooler...I wonder did they shorten the skirt or just add depth (weight) to the piston. Something to think about. Thanks for posting the pictures.
I'm very interested in finding out more about those pistons, they look very interesting, and I'm considering them for my engine. Where'd you get those, and if you don't mind, what was the price? I can't get the KB website to pull up, are these the same as talked about in this thread?
I'm not sure because that thread won't display. But I ordered them from Summit. Summit doesn't show them in their catalog, but by looking at the Keith Black part numbers that they do list, I just asked for UEM-KB357030-8 over the phone, and they got here in a little over a week. Cost is $357. I'm also doing a 383 SBC with these. On those, the rings aren't lowered nearly as much because the pin is so high. But the piston weight came out perfect with a SCAT crank and 5.7" rods almost as if it were a factory combination. I already took these Buick pistons to the machine shop, so I'll know what they weigh as soon as we get into the balancing phase. These can be run with as little as .0015" bore clearance, so the bore should certainly be much less out of round than that much. I will probably use .002". What makes these different than the old Kenne-Bell hypers is that they can be run loose if you want to without creating a time bomb. Their tops do run hotter so the top compression ring needs to be gapped slightly larger. But at operating temps, the gap should be normal. I'm trying to build a powerful but very clean running, efficient, non oil consumming 455 for one of my fullsizes and these seem to be ideal.
Thanks for the info! I finally got the KB website to pull up, and yes, those are the same ones. Sounds like you and I are shooting for the same 455 buildup! I'm after as much efficiency/power from an 87-octane motor as I can get in my LeSabre. I'm figuring on right at zero deck height, .040 gasket giving right at .040 "quench distance" to the head, should give just over 9.3 static compression, I'm hoping to get away with 87 octane fuel, haven't decided on the cam yet, but I'm looking for 7.5 to 8 dynamic compression. Just got my heads back from the machine shop, they've roughed-in the hardened valve seats and installed bronze guides, I'm going to do some bowl porting and chamber polishing. What are your thoughts on the above, and what are your plans?
I'm going with about .020" deck height and '73 heads. And with the .040" gaskets I'm looking for around 9.1:1 static compression. I'll be using the relatively small TA112 cam so there will probably be enough cylinder pressure to need 89 octane. Your setup sounds similiar so be careful trying to run 87 octane. Retarding the timing to allow for a lower octane fuel seems to make much less power than just going with a lower compression ratio with the correct timing. My buildup is for one of my 76 LeSabres that I no longer race. I just want it to be a strong stocker that doesn't need expensive gas. I left the switch pitch setup in it, but I'm changing to a converter that has lower stalls. I also took the 3.42 rear gear out and went to a 2.93.
I wish I could figure out how to put a table up on this board...I've attached a .jpg of my excel spreadsheet on 455 compression ratios with various smaller cams. The first section is the engine specs, the second is comparisons of various cams, their intake closing spec, and duration, and the last section is just a table of various intake closing points and their DCRs in the spec'd engine. From what I can figure, the problem is that getting close to .040-to-.035 on the "quench distance" for great detonation control means that the static compression goes up over 9.4/1, which means using a "bigger" cam like the TA212 to reduce the dynamic compression back down to 7.5, the lower end of the recommended range for "pump gas" (which means 93 octane to most folks, but means 87 octane to me and my wallet). All of which may well be fine, as long as I'm not getting too much overlap (48 degrees with the TA212) that the cam is killing off the mileage potential. But then, I might not need to worry so much, as I'm planning on using a stout THM200-R4 with its .67 overdrive. I'm just anal enough to worry about not getting the combination dead right and leaving some power/efficiency on the table... :Brow: Ideas? I think I'll post this over on the "Resto HP Engine" thread and see if I can spark some discussion from the big dawgs.
455 pistons :Brow: Are these the same pistons? This link shows the 455 pistons. http://www.cnc-motorsports.com/product.asp?ProdID=12866&CtgID=
That looks like 'em. ..and at a way better price than Summit, especially for me since I had to pay the state sales tax. As for compression, I will try to keep it down a little by staying at the upper end of acceptable quench, like .055". And to help a tiny bit more if any, I may put the TA112 cam in at only 2 degrees advanced. Polishing the combustion chambers might help because of hot spots and just because they'll grow a little. 89 is going to be right on the edge, but I think I can make it work. I don't want the TA212 cam in this car. I have that cam in the Riv's 430, and although it runs strong while still having surprising low end torque, it is not a very good gas mileage cam. The last cast iron headed true 10.0:1 engine I put together would NOT run on 89, so I won't try that again. I tried everything but reversing the coolant flow. Anything I did like timing retard and rich mixtures made it less efficient than just going with a lower ratio and more cubes, so that is what I am doing to that one.
update I can no longer recommend these pistons. I put them in at the exact skirt clearance they specify, and had a disturbing amount of piston slap. It was to the degree that it didn't even completely disappear at full operating temperature. Upon disassembly, I found evidence of severe rocking at the top and bottom of the bores. The rings had already left noticeable polished areas where they change direction because of the shifting around they were doing. This was only after two weeks of use. I did verify that the skirt clearance still measures what it was installed at, which is .0025- exactly what they specify for >4.1" bore applications(measured at the specified location). Bore size ended up right on about .0305 over. But the cross hatch is completely gone on the thrust side of each cylinder where the piston turns around. Pistons still look perfect, although they are headed for the trash can. I don't use hypers because they are slightly cheaper, but because it's what I prefer to use in the <550 hp street builds. I have plenty of engines with forged pistons because their use was merited. But I've used the Speed pro H392NCP for years in another motor with perfect results giving virtually no oil consumption, no start up noise whatsoever, and no failure. I do watch mixture, timing, and type of fuel, but I would in any case. I just thought these KB pistons took the idea of quench another step towards efficiency and that they would be perfect for what I was doing. I must admit that they did run very strong for as mild as that engine was, and that this engine was surprisingly resistant to detonation for the compression it had. But piston slap is the last thing I want to hear coming from any engine that has hypereutectic pistons in it. So my advice to anyone considering a hypereutectic piston, is to stick with the tried and true Speed pro(fed mogul), which performs flawlessly if installed and operated properly. I'm not sure what is wrong with the Keith Black piston, but someone didn't do their homework on the KB357. Maybe the wrist pin is not offset enough, or at all. The skirts are quite short, and their taper seems to excessive as clearance at the wirst pin level is more like .007-.008 and maybe more. The bottom line is that one of the selling points to these pistons is how quiet they are supposed to operate. Yet with them installed as per the instructions, they were more noisy than any of my forged piston motors are on startup, without totally going silent no matter how hot. At least the forged piston motors shut up rather quickly. What a waste of time and money these pistons have caused.
Man, that's NOT good!!! :error: :rant: I'd be curious to hear what they have to say about it, if anything. o No: At least I dawdled long enough on my 455 to learn from your bad experience, if that's any consolation. Speed pro H392NCP, you say? (wanders off looking for pictures...)
.007"-.008" :shock: . I just measured a 70 455 stock piston. 1 SRP, 1 Speed Pro forged 2362, and a Speed Pro hyp. H392NP. I can tell you none of these pistons have a 7-8 thou. difference from the bottom of the skirt to the top where the pin is. It's no wonder there was so much slop in there. What junk. I hope you get you're money back. Ray
