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whats the better vortec head casting # for flow 12556140 or 12557113

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Old 01-03-2006, 04:48 PM   #1
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whats the better vortec head casting # for flow 12556140 or 12557113

Anyone out there have any info on these casting #s ? The 12556140 casting came as a stock head in my 1998 vortec 4.3l engine with std rockers . The 12557113 casting i just got from a wrecking yard out of a 2000 s10 pu with the oem roller fulcrom rockers.Other than the slight hp increase going from std rockers to oem rockers are these castings ( 12557113) flow or are better in anyway than my current setup.( 1998 4.3l stock eng, k&n filter, cat delete,2.5" single exhaust, hand held flash program by street & performance). Btw i did a search on the 1257113 & found some info that it was a better casting, but no reason why, & no info found on the 12556140.Thanks. toyrocs
Old 01-03-2006, 06:02 PM   #2
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Re: whats the better vortec head casting # for flow 12556140 or 12557113

The only reason I can think that they are a better head is because they are a full roller head. That can be the only reason why. I mean they are both Vortec heads just yours are the older non-roller heads.
Old 01-04-2006, 10:01 AM   #3
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Re: whats the better vortec head casting # for flow 12556140 or 12557113

Flow numbers should be exactly the same for both heads, like Dan said the only difference is the roller fulcrum rockers in the 2000 set.
Old 01-04-2006, 05:42 PM   #4
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Re: whats the better vortec head casting # for flow 12556140 or 12557113

Wonder why the engine with roller fulcrums dont make more power,
or they're not rated for a little more power. Still reduces alot of friction.
I know its still the stock 1.5:1 ratio... but am I missing something?
Old 01-05-2006, 12:36 PM   #5
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Re: whats the better vortec head casting # for flow 12556140 or 12557113

Quote: Originally Posted by j894
Wonder why the engine with roller fulcrums dont make more power,
or they're not rated for a little more power. Still reduces alot of friction.
I know its still the stock 1.5:1 ratio... but am I missing something?
There's maybe a slight difference in power, I wouldn't say anymore than 1 or 2hp at most though so it's not worth re-rating the engine to 182hp.
Old 01-05-2006, 01:15 PM   #6
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Re: whats the better vortec head casting # for flow 12556140 or 12557113

Exactly. Running a full roller rocker is going to free up a very little hp. Nothing that you would notice.
Old 01-05-2006, 03:19 PM   #7
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Re: whats the better vortec head casting # for flow 12556140 or 12557113

Just wondering, cause it hasnt really been mentioned before.
I figured with the reduced fiction, it had to do something.
just curious.
Old 07-09-2009, 09:02 PM   #8
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Re: whats the better vortec head casting # for flow 12556140 or 12557113

Quote: Originally Posted by j894
Just wondering, cause it hasnt really been mentioned before.
I figured with the reduced fiction, it had to do something.
just curious.
Yes the reduced friction thing with the rollers was what I was thinking also. Maybe reduced emmisions/ higher gas milage/ lower noise/ longer engine life( less wear on valve guide/ seal ) less oil comsumption ?

Toyrocs
Old 07-09-2009, 09:07 PM   #9
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Re: whats the better vortec head casting # for flow 12556140 or 12557113

What would GM be doing with this change ( add rollers) if it didn't improve something? There is a reason for the rollers because every penny in production costs add up with the high production volume . They wouldn't have done it for "fun" or more power in this class of engine --- it's not a "sports" engine .
Toyrocs
Old 07-09-2009, 09:50 PM   #10
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Re: whats the better vortec head casting # for flow 12556140 or 12557113

A good possiability is they wanted to be able to change the ramp speed for the new cam that eliminated the need for the EGR, which was a cost savings
Old 07-10-2009, 07:55 AM   #11
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Re: whats the better vortec head casting # for flow 12556140 or 12557113

Quote: Originally Posted by toyrocs
What would GM be doing with this change ( add rollers) if it didn't improve something? There is a reason for the rollers because every penny in production costs add up with the high production volume . They wouldn't have done it for "fun" or more power in this class of engine --- it's not a "sports" engine .
Toyrocs
not sure if fuel economy played a role or not, the economy
gains would have been only a fraction of a mpg.

IMO, the switch to oils with lower levels of ZDDP
probably was a bigger factor.
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