Piston Selection

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    Author Topic: Piston Selection  (Read 1592 times)

    Offline 70RAGTOPR/T

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    Piston Selection
    « on: December 17, 2005 - 08:54:12 AM »
     :newbie:  Ok, chally wise men I need your help.  I'm starting to restore my r/t.  The car is numbers matching except for the block.  The orginal was blown many years ago while racing a vette.  My cousin won the race but lose the war due to a Philly pothole.  I have obtained a 70 hp block and had it boiled and measured.  The shop said the block is sound but rough.  It will need to be bored to .030.  That's fine with me.  What pistons should I use?  The shop needs to know.  Also, should I have the shop buy them or should I.   Your feedback is really welcomed. :feedback:

        1)  I'm on a budget, 2 kids in college.
        2)  I don't want to race this car but want some more HP.
        3)  I want to keep it looking orginal in memory of my late cousin.
        4)  The heads have been ported and polished with new valves and springs for MOPAR's cam P4286677.  Next cam up from the resto cam
        4)  The car will be driven mainly on weekends when it's nice outside.  The R/T is a ragtop.
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    Offline Grancoupe

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    Re: Piston Selection
    « Reply #1 on: December 17, 2005 - 10:58:07 AM »
    I went with a set of Wiseco Pistons for my 383. They asked a few questions about measurements that the machine shop should be able to answer. The tolerances were near perfect. The balance from piston to piston ws very close as well. This makes life easy for the machinist to assemble and balance the assembly.
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    Offline Rob C

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    Re: Piston Selection
    « Reply #2 on: December 17, 2005 - 10:59:30 AM »
    I have had good luck with Hyperutecic pistons from KB. The Federal-mougal units have an anit friction/scuffing coat on them to boot. Ethier set of pistons are cheap and strong. Set ring gap as per instrucitions. Very important.
    Regular cast pistons are fine for general use, you just have to know the actual piston height to calulate compresion. Most manufactures of standard cast pistons do not offer increased ratios. But it's possible.
    Since your not raceing it, ethier will do.
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    '73 Cuda, 360, 4psd & 4.10's
    '79 Dodge Magnum, 360, 727, 9-1/4 W/3.55's

    Offline 70RAGTOPR/T

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    Re: Piston Selection
    « Reply #3 on: December 17, 2005 - 11:59:16 AM »
    Thanks , Grancoup and Rumblefish, you both suggested the same pistons that the shop suggested.  He would prefer to use KB since he can get a forge piston.  He would like to stay away from the cast, but if there is a big $$ difference then he will use the cast.  I found out that the crank will have to be ground also.  So far the boring, grinding and the Magnafluxing will cost $320.  Is this a good $$.  Last, he wanted to know what cam am I going to use.  I gave him the heads so he could make an informed decision.  I will post pictures after the holiday.
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    Offline 71383bee

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    Re: Piston Selection
    « Reply #4 on: December 17, 2005 - 04:04:20 PM »
    I know that you are on a budget based on your previous post, but when i went down this road with the 383 I should have specified pistons that are either zero decked or darn close to zero deck.  I used the KB 162's I think and did not mill the block or heads.  The problem is that these pistons sit way down in the hole and with 906 heads it yields a very low compression around 8.3:1 or so. 

    It's taken me over a year of tuning and curving the distributor to finally get the car to run close to the way i wanted it.  I found out that despite the ability to run it on 87 octane it needs a ton of initial timing and a much leaner Demon than I trully want. 

    it is far easier to reduce compression through thicker gaskets than it is to try and gain compression after the short block is assembled so I think it's worth it to get good pistons that give you higher compression.   :2cents:

    BTW i tyhink KB has corrected this with a new set of pistons...I believe they are the KB 400's?
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    71 - 383 FC7 Super Bee

    Offline Chryco Psycho

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    Re: Piston Selection
    « Reply #5 on: December 18, 2005 - 01:14:37 AM »
    I will NOT use a Hyperutectic piston , go witrh the Speed Pro 2355 , the price is reaonable & the pistons are indestrucatble & wil take more punishment if you want more power later
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    Challenger - You`ll wish You Hadn`t

    Offline 70RAGTOPR/T

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    Re: Piston Selection
    « Reply #6 on: December 18, 2005 - 01:27:38 PM »
    Chryco and Bee thats for the inout the shop wants to keep the compression near 9:1.  I will present him with your suggestions.  Again thanks for the input.
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    Offline Chryco Psycho

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    Re: Piston Selection
    « Reply #7 on: December 18, 2005 - 01:50:21 PM »
    I would try to be in the high 9 to 1 compression , it will be fine on premium pump gas at 9.8:1 
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    Offline 70RAGTOPR/T

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    Re: Piston Selection
    « Reply #8 on: December 19, 2005 - 07:05:58 AM »
    Chryco, thanks for the information.  I will inform the shop.
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    Offline 70RAGTOPR/T

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    Re: Piston Selection
    « Reply #9 on: December 19, 2005 - 07:13:54 AM »
    I do have anotjer question to ask.  Since the crank has to be ground, should I go with new rods or see if the old ones are still good.  The shop wants to charge $90 to recondition the old ones, but they are over 30 years old.  I know there are lighter weight  rods out there.  If I go with new rods, who should I use.
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    daves70

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    Re: Piston Selection
    « Reply #10 on: December 19, 2005 - 05:44:39 PM »
    I would use the speedpro teflon coated pistons. More bang for the buck.
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    Offline matt63

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    Re: Piston Selection
    « Reply #11 on: December 19, 2005 - 06:38:19 PM »
    I thought the Eagle I beam rods were a good deal as compared to refurbishing old rods.  They are lighter and come with ARP bolts but I had to get the big ends resized and the bushings sized for the pins so its not as cheap as it seems.

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    Matt in Edmonton

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    '73 Cuda 340 4 speed (408) SOLD

    Offline Chryco Psycho

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    Re: Piston Selection
    « Reply #12 on: December 20, 2005 - 12:34:30 AM »
    the old rods will generally work well , you need to polish the beams & get them balanced , any after market rod will cost more
     I think Scat have the next cheapest new forged rods , Eagle are good too but I have heard they may not have the life cycles in them that the stock rods do but they will still have a ton less cycles than 30 year old rods do
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    Offline 70RAGTOPR/T

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    Re: Piston Selection
    « Reply #13 on: December 20, 2005 - 05:29:50 AM »
    Thanks everyone for yourinput.  I will pass this information along to the shop.
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