BB quench Q & A

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    Author Topic: BB quench Q & A  (Read 1967 times)

    Offline BB73Challenger

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    BB quench Q & A
    « on: December 31, 2012 - 06:07:42 PM »
    So I'm at a crossroads.
    After many searches, googleing and pondering, I still need a little help.

    440 iron block with a 500 stroker internals
    Would like to use aluminum heads ( and maybe this is my big stumbling point )
    Street/strip
    Would push 10.85 to 10.9:1 static comp ratio
    Still out on cam selection / dynamic comp ratio

    Block has been machined recently, so I wanted to work around existing block & rotating assembly.

    So here is where the quench comes into play...

    The pistons at Top are .020" in the hole, and the thinnest MLS gasket I can get is .027".
    I would ideally like a .020" gasket for a .040" quench, but not going to happen without using a steel shim gasket.
    Is .047" to even .050" too thick beyond "good" quench?

    I've read even .045" is beyond good quench and anything beyond .040 falls off very quickly.
    I've then read .050" is the large end of good and .060-.070 is the fall off.
    My concern would be octane stability for premium pump gas with the higher comp ratio.

    Any help or thoughts would help!
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    Jeff from Cleveland, Ohio


    Offline 72cudamaan

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    Re: BB quench Q & A
    « Reply #1 on: December 31, 2012 - 11:49:17 PM »
    I would think you would be better off zero decking the block and using a good cam to bleed off some cylinder
    pressure. Sounds like you haven't picked the heads yet, so how can you have determined the c.r.?
    You may be able to use the eddy 84? cc heads to lower your compression.
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    Andy  (phukker whither)

    Offline 72cudamaan

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    Re: BB quench Q & A
    « Reply #2 on: December 31, 2012 - 11:51:03 PM »
    And yes, .040" is the desired quench. A zero deck with a standard gasket will usually yield a .039" quench.
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    Andy  (phukker whither)

    Offline BB73Challenger

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    Re: BB quench Q & A
    « Reply #3 on: January 01, 2013 - 04:10:09 PM »
    Quote from: 72cudamaan on December 31, 2012 - 11:51:03 PM
    And yes, .040" is the desired quench. A zero deck with a standard gasket will usually yield a .039" quench.

    That's what I would have done - if anything .010" in the hole, but not my combo. That's really the easy way to go.

    Correct on no head selection yet, I'm running Eddy's on another 400 based 500 and I do like the higher cc chamber's than some of the others out there.
    The ballpark static comp ratio I have is due in part to the swept cylinder volume with the particular flat top piston in it now (bench-top building with some other on-line calculators) AND looking to use the 84 cc heads.
    I'm tinkering with a build of a street/strip car with this potential power plant that I can get the short block for, but I've got a 440 stock specs I might as well just have machined the way I want.

    Thanks for your input & everyone have a good & prosperous new year  :wave:
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    Jeff from Cleveland, Ohio

    Offline TROUBLE987

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    BB quench Q & A
    « Reply #4 on: January 03, 2013 - 01:00:46 AM »
    If you decking the block,make sure you fix the intake..
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    Offline Chryco Psycho

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    Re: BB quench Q & A
    « Reply #5 on: January 03, 2013 - 05:39:38 AM »
    I tend to believe the quench will be good up to about .060 , the highest I have gone is 10.6 compression & 3500 ' altitude & got away with it on 92 octane Pump premium , it would ping at about 36* timing but was fine at 35* , results would differ at sea level though . , this was with a 245/ 252 * solid cam with .22 lash so relatively small cam .
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    Challenger - You`ll wish You Hadn`t

    Offline 73restomod

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    Re: BB quench Q & A
    « Reply #6 on: February 26, 2013 - 01:56:59 AM »
    You could have the piston tops milled to give a small dish, if you are running flat tops. This sounds odd I know, but when I was a wee tike my father raced a 327 chevy 2 nova. He bought 13.5 to 1 Mickey Thompson pop-up pistons. He eventually wanted it to be more street-able so he took out the pistons, had them machined at a local shop, and stuffed them back in. Car ran perfect till he sold it 6 or 7 years later. You will have to get it re-balanced, but they will only have to remove material, not add it, so cost will be low. My point is you may not be as restricted as you think using an existing platform.

    Sent from my DROID RAZR using Tapatalk 2
    « Last Edit: February 26, 2013 - 02:03:59 AM by 73restomod »
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    Offline cudabob496

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    Re: BB quench Q & A
    « Reply #7 on: February 26, 2013 - 03:16:29 AM »
    On my 496 I had it put together to have zero deck height with dished JE pistons. Supposed
    to make for an efficient combustion chamber/power maker. Ported Stage VI alum heads and 10.5 CR.
    At least back in 2000 it was the way to go.
    « Last Edit: February 26, 2013 - 04:07:37 AM by cudabob496 »
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    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline 73restomod

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    Re: BB quench Q & A
    « Reply #8 on: February 26, 2013 - 03:47:23 AM »
    The other cool thing about milling a the piston, is that it allows you to match the dish to the chamber's shape. Making the combustion cleaner and more complete with optimization of quench.

    Sent from my DROID RAZR using Tapatalk 2
    « Last Edit: February 26, 2013 - 03:49:20 AM by 73restomod »
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    Offline moper

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    Re: BB quench Q & A
    « Reply #9 on: February 26, 2013 - 12:53:02 PM »
    512 (440+.030 w/4.25 stroke): 10.8:1 static. Dished (12cc) pistons at .004" proud of deck. 84cc RPM heads were "stage 1" hand ported by me. runs the .039 gasket for .035 quench. Port matched 6bbl induction. Engle Solid flat tappet. Makes around 550hp, 600tq on pump fuel.
    The key to quench is closeness. The closer they get to each other ,the more effective it is. I don't consider it a quench build if there's more than .045" there. It simply has less affect as the distance gets wider. As my golf buddy says "Closer's better!"
    In this case - if you you have the shortblock done - I would ignore quench totally and run the gasket that Edelbrock suggests and run a cam that is larger than 250° @ .050. That will keep you out of trouble with pump premium.
    If you want to "do it right" at least by my thinking then get dished pistons to zero deck (must square deck the block - not just "deck it"), and run the .039 gasket which is what Edelbrock recommends.
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