So a few weeks ago I asked about pistons, since I'm not decking the block, I was led to claimer pistons that had a proper pin height for the CR I want to run. I was always led to believe that "claimers" were built with inferior products. My question is what longevity can I expect from a claimer piston, vs a rebuild piston? Are there differences between them, like alloys used, etc.? Thanks.
Im guessing claimers are cast pistons.I have never seen rebuilt pistons.In the old days guys would knurl the sides to bring them up to specs at least for a while.I haven't seen a shop do this in years.There are decent quality pistons at the low end dollar wise at least for the real common engines like the 350 Chevy.
Not "rebuilt", but rebuilder pistons, seems the rebuild pistons are made with a pin height at .020 less than factory would be, consensus was it was assumed the block would be decked. I'll call a manufacturer late next week (starting another night shift tomorrow) but was looking for insight with those who have run them and can I get 150-200K miles from them? I want the engine to last my kid till she tosses it, I want it to last another 20+ years where I'll be too old to pull it out and do it again
if your not decking the block I would just go with a standard type piston.Going shorter is going to cost you compression.
The "claimer" part of the name is mostly marketing, and came about for for circle track classes that have a "claimer" rules provision that puts a supposed cap on how much can be spent on the engine build...not that you can't spend more than that, but could prove foolish to spend $5000 on an engine build when the class "claim" amount is $2500. What it meant was any finisher in the top 5(or in some series, still on the lead lap) was eligible to put up the "claim" amount and take the one of the top finisher's engine, on the spot, removed in less than 1 hour. When speaking of the UEM/Keith Black "claimer" hypereutectic pistons, they are only offered in a couple of styles(simple dish, flat top, one or two different dome sizes) for a few commonly raced engines like the 350, 383 stroker, 400 SBC, and maybe 351W Ford, 360 Mopar, a few BBC 454 pistons, etc. Common engines, high volume sales and elimination of fancy machine steps keeps cost down while quality is still good. They are typically a plainer finished piston than the Keith Black Signature series Hypereutectic, have a as cast valve pocket instead of machined, T5 instead of T6 heat treat level. Anything short of a 500 HP, 6800 rpm engine will have no problem with durability, as long as the tune is good....like any hyper or plain cast , detonation will shatter them. They are a lot better than just plain cast, just a tick below the fancier fully machined hypers, and a step below actual forged pistons. I've personally run them in 383 SBC, to 7000 rpm, solid lifter, low 12 second 1/4 mile street/strip engines several different builds in 3500 lb cars( so 425-475 Hp-ish) and not had any trouble with them at all, the UEM/KB's and the formerly Federal Mogul "Sterling" which I think got folded into Speed-Pro/Sealed Power. They are a far better choice than any of the shorter height "rebuilder" style hypers that are often available even cheaper. (I.E. Sealed Power 345 CP/NCP, etc)
Thanks @Ericnova72 . Just the kind of info I was looking for! Now to go shopping again That was my understanding on claimer races, build a motor as inexpensive as you could and let it go without taking a loss, generally would mean use the least expensive parts to screw it together that would last. I always took that as buy at Walmart, and get Sears money for it. Thanks
See, I was enlightened about this same thing a few weeks ago. So a factory SBC has the pistons in the hole at .020? or .025. The factory pin height is 1.60 as I recall, to achieve that CR stated. The "rebuilder" pistons are at 1.40? as I recall, which on a stock deck, puts them .020 lower in the hole. The claimers come in different flavors and can keep you in the proper spot for quench and CR with the head gasket being the final factor.
We used to run claimer type engines. Hy Duty, Badger and Ohio were the pistons of choice for the cheapest stuff. Cast, kind of crude but did the job even on alcohol....if you were tuned correctly. A tad lean or the wrong heat range of spark plug and they were junk in a couple laps. Most of those engines were actually limited by the use of stock type connecting rods. about all we did back then was new rod bolts and resize them. The next step up was when they came out with the KB hyper pistons. Much nicer than the older cast stuff and were a little easier to work with. Follow the ring gap instructions to a "T" and you would be fine on a street engine. Get the gaps wrong, butt the ring ends and blow the top off the piston. The KB's came out about the time better rods (offshore knockoffs or Carrillo) came out. Stepped the whole engine up when combining the new technology and didn't cost that much more than the cast stuff and rebuilt stock rods. I wouldn't be afraid to put an engine together with either if it was a cruiser. If you plan to race it any, buy better stuff. Pay me now or pay me later type deal. SPark
She'll probably the rev limiter I put in it, the engine (as I am planning it) should make HP up to 5300 or so, before it falls off. The engine isn't HAMB friendly other than being a SBC.. I'm lloking at high 200's in the HP range and tq will follow correctly.. So the last few SBC's I screwed together, I bought .030 rings, checked them and needed no filing.. Reeducate me on the Hypers, as I recall they fit looser but expand more? Thanks
Hypers fit tighter and expand less as far as piston clearance to cylinder wall. Usually a 350 Chevy with Hypereutectic pistons will only require about .002-.0025" clearance but ring end gap on top ring needs to go up to about half again that of a normal cast or forged piston.
The squish area on top of the Piston is important. If you put a Piston in that's too far below the deck it could lead to serious problems. Better to deck the engine and get it right and additionally make a good surface to seal the head gasket. Since you want the engine to last, a good sealing surface is important too.
Regarding the whole claimer deal. I know that term was/is big in roundy round circles, may have been more of a regional thing, being a drag related guy I've never had the process explained fully. I will say there had to have been many tense situations when this was in effect, nobody easily gives up an engine regardless of the fact that they "bought into" the arraingment.
I've used several different styles of KB pistons back when we ran claim stuff. They come with an instruction sheet that tells you inches of gap vs bore and engine use. Read the chart and FOLLOW IT! SPark
Well I'll measure a piston in 4 corners when I get the block back in the next week or two, but assume the block is square. And assume GM did it right the first time and I really am .025 in the hole. I think I read somewhere that they used an .023 steel shim gasket when new...but regardless. So if the block is square and I use a piston with a pin height of 1.65 (vs factory 1.60. I may have the numbers off) I can adjust quench with the proper headgasket, no reason to deck the block (assuming it's square). Reason I'm doing this is to get the CR up to 9.6 or so, plus the factory pistons leave a bit to be desired.
Most circle track's that use a claimer rule have strong penalties for refusing a claim...such as banning said racer from further racing at the track for the rest of the season in the same or any other class at the track, loss of accumulated points, loss of any winnings that day, even banning them from all races at all participating tracks if it is a traveling series, etc. From the tracks rules standpoint, they are trying to control costs by preventing someone with a load of money into an engine having an unfair advantage in what is supposed to be a budget level class. That's the whole point of a claim type limit. Level playing field, supposedly.
For a 350 using stock length 5.700" connecting rods, the stock compression height for the piston is 1.560", the cheap 'rebuilder' stuff can be found that is either 1.548"(.012" below stock) or more commonly 1.540"(.020" below stock). Factory steel shim gasket was .015" to .018" IIRC With a stock height piston of 1.560",or the slightly better KB Claimer with a 1.565" height, you can get into the good quench range of .035-.045" on an uncut block using either the available steel shim gaskets in the .015-.018" range, or the Mahle Originals/Clevite graphite composition gasket PN #5746 that is .026" thick. KB also has a "Claimer" 2-valve relief(5cc) flat- top that is 1.265", it is for use with the longer aftermarket 6.0" connecting rod if you want to go that route. It comes out the same distance below deck at TDC as the 1.565" claimer for the 5.7" rod does, so gasket choices are pretty much the same. Hopefully I won't overcomplicate things for you with this last bit of info, but there is also a third alternative.... KB offers a 1.433" tall comp height piston, meant for use with a 5.7" rod and a 3.75" stroke to make a 383...but it can be used differently with a different length connecting rod. If you use it with a 3.48" stroke crank(regular 350") and an aftermarket 5.850" connecting rod(Eagle makes several, one in the near stock appearing type SIR line is about $240, along with making the better race H-beams) along with this 1.433" tall piston you end up with a set-up that is just .002" down the bore at TDC in an uncut block...nearly zero deck, which gives you a bunch of composite gasket choices. 1/2 stroke(1.74) = 5.850" rod = 1.433" piston = 9.023" parts stack, in a nominally 9.025" stock deck block.
Thanks @Ericnova72 , I figured I had the numbers wrong on the pin heights, I did cover my ass and say I may be wrong Interesting choices indeed. Is the preference a composite or steel shim headgasket?
Steel shim is fine as long as everything is FLAT. At the bare minimum, head needs to be surfaced to ensure at least one of the mating components is as flat as possible....putting a used and always slightly warped block deck along with a used head which is also nearly guaranteed to be warped together with a shim gasket can often lead to trouble....the whole reason the thicker composition gaskets were even introduced is to deal with re-assembly of not so flat surfaces in the service department. With thicker crush, they are more tolerant of imperfections. Best practice on a rebuild is have everything cut flat, that way you prevent any potential leak problem from developing....but I realize that block decking isn't always in everyone's budget, nor is it always a necessity.
I ran claimer classes and if the engine can be claimed for $800, you should have as little as possible in it. This is why we ran a Ford, nobody wanted those. The term claimer piston just got stuck on what is a base-line model of piston. Pin height varies by that .020 step in many that I have seen. I ran mine up to 6300 on a 1/4 mile oval track and 5800 on a 1/5 mile track and it made great power all the way up, this was in a 429 Ford and 396 Chevy.
I did have the heads surfaced. I've a friend with a precision straight edge and will check the block when I get it back. Looks like I'll be setting it up as-is and if I need to use the composites I will. When we started this she wanted a 383, but just not in the budget right now, hence why I'm glad I could be w/o boring it. Leaving the deck alone now gives us options in the future if we go that way. Thanks again all!
Thanks for the info on a 1.540 CH 350 piston, got a 1963 327 block machined and ready, also have a good 283 crank., looking at building a cheap 302 with out buying the expensive 302 pistons. Pondering building this long rod 302 283 crank 1/2 stroke = 1.5 6" eagle rods 6" Summit piston 1.540 with .015 off top = 1.525 total =9.025
The BIGGEST thing with the KB Hypers, was to keep as much HEAT in the piston top (heat ='s power), the top ring land was placed closer to the top of the piston. Now imagine what would happen when the ring ends butted together after getting up to temp, and throw just a little detonation into the mix. That's where the tops coming of the pistons came in, and WHY KB had such stringent specs for ring gaps. I've never been on-board with Hyper pistons combined with detonation concerns. Hypereutectic have a higher concentration of silicon used in them; harder aluminum but easier to break. Glass has silicon in it, and shatters when broken, unless it's tempered glass, then it fragments into little shards. And hypereutectic pistons also can shatter. I see a correlation there, anyone else? I am Butch/56sedandelivery.
That can work, other than the fact a flat top piston that makes this top trim job easy only gets you 9.02:1 compression with a 64cc head and an .041" thick head gasket on that shortcut zero deck assembly. To get any real compression you'd need to use ether a very small chamber head with the flat top(55cc just to get 10.0:1), or do some careful trimming in a mill of the quench area around a dome on an available domed piston to get your quench clearance right and still keep a dome on it.. Short stroke, small cube engines have a hard time getting any compression ratio in them with a flat top piston....you need a really small combustion chamber. Might be a great place for Dart Iron Eagle heads with the 49cc chamber option. (10.9:1 zero decked)
^^^Actually, most of them "come off" ABOVE the TOP ring land^^^. That's probably a much worse scenario, as now the piston pin/rod end can beat the h*ll out of the cylinder. looks like a really low mileage engine too. I am Butch/56sedandelivery.
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