ported heads

[Rootie524]

just some ported head questions. if i get ported heads would i need the 3500 valves or would stockers work? i already have springs so im good there. but idk if the bore will require the 3500 valves? and would i need a ported UIM and LIM for me to notice gains? or would i get good gains from just the heads?

based on what most of you know about my setup so far..what would be a good bore to apply? like how big and what not.

[SappySE107]

3500 valves are lighter and flow a little better than 3400, but you could use 3400 valves no problem. Ported heads alone could be a nice increase, if ported well. Manifolds aren't necessary, but compliment the heads for the best performance increase.

For bore, just as much as you need to clean up the cylinder walls IMO.

[Rootie524]

what are the size port you think would work well with my cam and a 65mm throttle body with 28lb injectors and S&S headers?

[SappySE107]

what do you mean the size port?

[Rootie524]

i used the wrong word. milling wise..how big do you think i should go?

[SappySE107]

How big? I still don't understand. What are you milling?

[Rootie524]

then i dont understand your listing for heads. whats the milling option about?

http://wot-tech.com/shop/all/sportsman-ported-3100-cylinder-heads/prod_148.html

[bszopi]

Milling is for the surface of the head, usually to ensure it is flat against the block.

[ForcedFirebird]

Milling is for the surface of the head, usually to ensure it is flat against the block.

Or to raise compression....

[SappySE107]

You can't gain much compression from milling the aluminum heads though.

[robertisaar]

You can't gain much compression from milling the aluminum heads though.

yeah, this ain't the 60s with iron heads that have a massive amount of material just sitting there and lowering compression. i think the BBCs were all bad for that actually, with like 150+cc chambers...

[geoffinbc]

Yea open chamber big block heads were 118CC and you could mill them down to 100 and even a little less sometimes.

[mfuller]

Isn't the larger combustion chamber of the 3500 heads part of why they make more HP? I figured a larger CC is better, as lond as you have high-compression pistons to squish the A/F mixture. In theory, a larger quantity of air and fuel makes a bigger boom, right?
Just as an aside, milling my 3400 heads .020" got me maybe .3 increase in static compression.

[robertisaar]

quantity of fuel is determined by displacement, not CC size/style(though there are exceptions to this rule)...

and the 3500 makes massive power above other 3x00s due to the massively improved flow. the bigger chamber offsets it a bit by lowering compression, but you would still come out ahead if you put 3500 heads on a 3400 block.

[Superdave]

the 3500 chamber is bigger because it was just re-shaped a little, it's still very similar to the 3400. 32cc vs 28cc.