243's vs 317's
 

I'm still pretty green with a lot of the LS stuff. Can some of you guy's with a bit more background care to school me in the pros and cons of a 317 vs. a 243 head? I know the 243's are a pretty nice head and are rather desired. But I know next to nothing about the 317's.

Reason I ask is i picked up a LQ9 6.0 for a S10 LS\T56 swap. my friend has some nice clean 243's off a tbss that he's no longer using. what are the pros and cons of the different heads on an Iron Block 6.0? this build is going to be a cam and bolt on truck at this point in time with tubo added later down the road. do the 317 flow about the same as the 243? im not wanting to raise the c.r with the mind of a turbo sometime down the rd, would i be safe running a thicker head gasket with the 243' and turbo? or just say forget it and run the 317's

Pretty sure they are the same head. But the 317's are better for boost.

They are the same exact head, except the 317s come with a bigger combustion chamber so they will provide a lower compression ration.

It all depends on what your build is and what sort of compression you want. For N/A, definitely go with the 243s. For boost, depending on the rest of your bottom end you might want to go with the 317s for lower compression.

243/317/799 heads share same intake/exhaust port design and valve size.
243/799 share similar chamber.
317 has significantly larger and different shaped chamber

thank you for the responses! other than the rods being resized for arp rod bolts, the short block will be stock. from what i gather from you guys, i will keep the 317 to keep the lower c.r. if there were a benifit to go to 243 with dished pistons i would but i just dont see that in the posts. thanks for your insite. i cant remember correctly but the top ring gap needs to be opened for boost to .023? is that the correct #? the middle ring is already gaped at iirc .023

stock rods are not resized like traditional rods. due to cracked cap design.
usually honed oversize and use thicker bearings

If you arent going to be running FI I would consider using the 243 heads, they should get you to around 11-1 compression, which with the aluminum heads should be fine on hi octane pump gas IE 93

i was under the impression that its a good idea to resize the rods if installing arp rod bolts due to the extra clamping force and diflection in the rod.... stear me in the correct direction on this one.

As he said oversize hone with thicker bearings. Problem is you can't get those bearings in a performance H type just p for the most part.

By the time you buy the bolts and pay for the machine work you might be better off getting some cheap scat i beams, etc. as they have larger arp bolts in them. You can get them in full floating pins for aftermarket pistons or press fit stock type. Not sure how far you want to take this thing though.