Re: Cast Crank and 10 to 1 pistons
[Re: Alikazam]
#1109942
11/09/11 01:30 AM
11/09/11 01:30 AM
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Joined: Dec 2007
Posts: 1,639 Brandon, Ms
cornet684me
OP
top fuel
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OP
top fuel
Joined: Dec 2007
Posts: 1,639
Brandon, Ms
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this is going into a 440, i think the key here is that i will have to pay the extra money and have the new pistons balanced. i was hoping to get by with just putting new pistons on the rods and getting by, i should have known i could not get out the cheaper way, thanks
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Re: Cast Crank and 10 to 1 pistons
[Re: cornet684me]
#1109945
11/09/11 01:43 AM
11/09/11 01:43 AM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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I'm doing the same thing on an extremely low buck 318 DD. Have some std pistons/moly rings and some viper rods (.098" longer). I dont care what the bore taper/out of round/clearance is. Shooting for .035-.040" quench and will machine piston notches to reduce the static CR. I'll decarbon the pistons/pins and rods in carb cleaner then weigh em then deburr/polish/trim the new rods/pistons (they're heavier) until the new piston/pin/rings weigh the same as the old and slap em in w some new bearings. You can get a HF digital gram scale (on sale) for less than 10 bucks and it is (so far) as accurate as my high dollar one (might not stay accurate forever) EDIT adding 302 heads/1&5/8 headers. Keeping the eddy 1406/streetmaster. An over the fender overhaul to use these std pistons I have and the headers that are hanging from the rafters and... it never ends
Last edited by RapidRobert; 11/09/11 11:40 AM.
live every 24 hour block of time like it's your last day on earth
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Re: Cast Crank and 10 to 1 pistons
[Re: cornet684me]
#1109948
11/09/11 12:17 PM
11/09/11 12:17 PM
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Joined: Feb 2005
Posts: 28,312 Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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I have done it twice lately, 340 and a 440. Built my latest 340 in 2007 and used a cast crank that I had that was stock and KB 243 10-1 pistons and did not have it balanced. I have over 10K miles on it now and have driven it all over the country on vacations, including extended 120 MPH runs on the salt flats at Bonneville. This past summer drove it to the top of Pikes Peak for the second time in 95 degree weather and then in 115 degree weather in Vegas for 5 days. Then back in 05 I bought a 440 short block that was freshly built with pistons that were .100" in the hole. I installed sealed power 10-1 pistons in it and did not re balance it. It runs great today. I hate to take my stuff places and try to do everything myself. Why bore a block if it don't need it? MY 340 is standard bore with KB standard pistons in it. I honed it myself with a portable Sunnen hone when I built it. So no it's not absolutely necessary to balance it, imo and experience. This past summer my power brake booster started leaking causing my 340 to pop on decell, I did a compression test on it first and it had 165-170# on all 8 cyls and it don't smoke at all, none. So the the clys sealed nicely, the motor you see below. Replaced the booster and all is well. It's idling in this picture at 13000+ altitude on the way down from Pikes Peak. It's a real test for a old car to make it to the top with a carburetor.
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Re: Cast Crank and 10 to 1 pistons
[Re: dogdays]
#1109951
11/09/11 06:42 PM
11/09/11 06:42 PM
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Joined: Feb 2005
Posts: 28,312 Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
The real answer is that most replacement pistons are made to be the same weight as the pistons they're replacing. So you should be able to swap pistons as long as you don't spend big money for lightweight pistons. Chrysler Corp factory balance jobs were notoriously bad, but the engines still performed.
Now depending on how much $ you have to spend, it would make a better engine if you DID buy lighter weight pistons and have it rebalanced. But on the cheap, swapping stock replacement for stock replacement doesn't require balancing. Think of the millions of factory rebuilt engines on the road and not one of those engines was rebalanced.
R.
Good info for sure. Thanks for posting Dogdays I just looked and the stock 71 hi compression piston in a 340 weighs 758 grams and the KB pistons weighs only 507 grams. I'd consider the KB243 a stock replacement piston at only $263 dollars a set.
Definitly would need to be rebalanced for competition and hi rpm use.
My street driven 340 has been a reliable motor even though it has not been re balanced with the new lighter pistons. I even own the fixtures and scales to determine bobweight. Just not the balancer...yet.
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Re: Cast Crank and 10 to 1 pistons
[Re: Challenger 1]
#1109952
11/09/11 08:42 PM
11/09/11 08:42 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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A Sealed Power, Silvolite, Ohio, Badger, Zollner, Hy-Duty, Nylen or Clevite piston would be a stock replacement. KB pistons are supposed to be high performance and even if they don't cost too much, it is ASSUMED that the purchaser knows they will make rebalancing necessary. It's the same for the ring gap requirements. I salute KB for making an affordable piston for a 340 that actually weighs like a smallblock piston and not a bigblock piston. But if your point was that a 340 needs to be rebalanced when using that piston you are absolutely right. No way is a 200+ gram difference going to go unnoticed, and probably right from idle and on up.
R.
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Re: Cast Crank and 10 to 1 pistons
[Re: dogdays]
#1109953
11/09/11 09:26 PM
11/09/11 09:26 PM
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Joined: Jun 2004
Posts: 893 Tustin, CA
pishta
super stock
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super stock
Joined: Jun 2004
Posts: 893
Tustin, CA
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oversized pistons from the same manufacturer of OEM replacement pistons weigh the same as the STD pistons they replace. Aftermarket performance pistons rarely weight what the stockers weighed. MP pistons, stock or HP/stroker whatever are not as close as Probe or other high end pistons. My stroker set were only within 7g of each other, some good manufacturer sets are within 1g or less. I had to lighten them all to the lightest one, 7g is alot to be taken off a short stroker piston. ended up taking a few g's off the pressed pin.
12 Grand Caravan 06 T&C 02 T&C 96 Breeze 65 Barracuda "S"
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Re: Cast Crank and 10 to 1 pistons
[Re: Challenger 1]
#1109954
11/15/11 01:28 AM
11/15/11 01:28 AM
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Joined: Dec 2007
Posts: 1,639 Brandon, Ms
cornet684me
OP
top fuel
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OP
top fuel
Joined: Dec 2007
Posts: 1,639
Brandon, Ms
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does anybody have the part number & name of pistons for the 10 to 1 pistons that i wld need to go with, looks like i wld want just to swap out the pistons that i have for the stock replacement 10 to 1 compression and not balance the motor.
trying to get by on a budget, i want to unbolt the heads, take out the pistons and rods, have the new pistons pressed on the rods and reinstall without taking out the crank. the motor is already completely rebuilt , just has the smogger pistons.
this is going into a 440 with a cast crank.
Last edited by cornet684me; 11/15/11 01:35 AM.
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Re: Cast Crank and 10 to 1 pistons
[Re: cornet684me]
#1109955
11/15/11 01:32 AM
11/15/11 01:32 AM
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Joined: Jan 2003
Posts: 75,020 U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,020
U.S.S.A.
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Quote:
the motor is already completely rebuilt , just has the smogger pistons.
How many miles on it since the rebuild ?
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Re: Cast Crank and 10 to 1 pistons
[Re: JohnRR]
#1109956
11/15/11 01:41 AM
11/15/11 01:41 AM
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Joined: Dec 2007
Posts: 1,639 Brandon, Ms
cornet684me
OP
top fuel
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OP
top fuel
Joined: Dec 2007
Posts: 1,639
Brandon, Ms
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none, i bought the motor off craig'slist., the motor was rebuilt 3years ago by a rebuilding company out of spokane wa. complete long block, 69 block, however, used cast crank , i am just wanting to get the motor back up to 10 to 1 compression.
the motor was still on the crate, has been oiled up and rotated every so often.
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