JustAFooL

iTrader: (45)

Its finally came time to purchase a set of heads. Due to my budget, I'm definately trying to go with the "used" route.. So, now that I've been looking for about a week, I realize how lost I am on knowing what I am actually looking for.

I tried a search on casting numbers, but couldn't get any results. I'd like to know what casting numbers match with what motors. (ex. are 243's from a stock LS1??) I'd also like to find out about milling. What does it effect on the heads? Thanks in advance for the help..

redbird555

iTrader: (14)

806, 853, and 241 heads are from a stock ls1. Ls6 and ls2 mootors came stock with 243s which are worth about 20hp over stock ls1 heads.

Milling essentially removes material from the bottom of the heads this making the combustion chamber smaller and increasing compression. This will usually increase power but if you mill too much off and get too high of a compression ratio it can actually hurt you because the engine will not run on regular pump gas..

I'm not sure what the budget on you build is but if you are pretty limited a set of used 243s will run around 400 add a TEA port job and you'll be around a grand. With that and a decent cam you will be well over 420 at the wheels through a 6speed

JustAFooL

iTrader: (45)

I'm already running a 230/236 cam with full bolt ons and 4k stall. My converter went out on me about a month ago though so I figured while the car is down, it will be a good time to throw heads on there with atleast an ls6 intake.

Your answer to my question was in-depth and helped a ton. Now, I understand your saying they cut a small amount off to increase compression but what is a factory head cut to?? For ex., you constantly see milled to 62cc or what not. How much is usually cut off?

And as far as budget goes, I'd like to keep it under 1k for sure. You say though sending a set of 243's to TEA to be worked would be a good idea, what about buying a set of used 5.3's off ebay and sending them in?? I'm open to all suggestions and information. I'm in no hurry as its winter right now so I got plenty of time to make a good decision..

JustAFooL

iTrader: (45)

Nobody else??

fastazzls1

i have 5.3 stage 2.5 heads on a trans am and it bumped the compression up a couple of points also with increased compression you have more of a risk damaging vital engine parts with out proper timing and fuel stratgies also will help increase torque due to higher cylinder pressures generated on compression stroke, also you need to figure in max lift that springs will handle, head gaskets ,bolts or studs and any other thing you will be needing i would recommend new lifters and trays while you are in there if wasnt done with new camshaft also to answer you question about 62cc combustion chamber size is the volume of the combustion chamber, imagine you had the head flipped over and combustion chamber up it would hold aproxmiatly 62 cc of water also flow numbers are important

JustAFooL

iTrader: (45)

I understand about the cc's in the combustion chamber. What I'm asking is how do you know how much a head has been milled??

So I'm guessing that the smaller the combustion chamber's are in cc's, the more compression the motor will have, correct??

SweetS10V8

iTrader: (4)

No way to tell how much has been milled off, since it takes off so little. The best way to get a guess-ta-mate would be to buy a cc kit and measure. If they are smaller, they have most likely been milled. Like this... http://www.summitracing.com/parts/CCA-4975/

Correct, small combustion chamber = more compression

hfthe3rd

iTrader: (1)

I'm in the same boat trying to figure out buying a used set of heads too.

JustAFooL

iTrader: (45)

Ok, I may be slowly starting to figure a little bit of this out. At what point does it become a problem with pump gas? I know more compression makes more power, but when do most people draw the line?

SweetS10V8

iTrader: (4)

"It depends" there are many variables such as gas used, camshaft, dynamic compression tuning ability, etc.

OEM cars are coming out with 11:1, stay in that ballpark and you should be just fine.