1jfuddle

iTrader: (7)

I am considering a set of aluminum truck heads. Casting 317 using the LS6 design. I've heard conflicting ideas on using these heads. What are your thoughts? If I don't do any work to them, what valve size do I want?
Also, will they work on a 98 block?

INVISIBLEZ

iTrader: (45)

They're not worth it if you don't port them. You'd do better to go with a 241 casting head. 317's are for bigger 6.0 engines, unless milled and ported for a 346 c.i. engine. You would'nt have any compression, so you'd hurt yourself instead of help yourself.

BrentB@TEA

they also do not flow as well on the smaller 3.9 bore. Your best bet is a set of "TRUE" ported LS6 heads followed by ported 5.3 truck heads.

Zedzag

iTrader: (7)

Brent, how well do 317 heads flow on the larger 4.0 bore ? Would a 6.0 see the same gains with a cam as a 5.7 does?

1jfuddle

iTrader: (7)

As far as the flow, I was under the impression that they had the basic LS6 design as far as intake and exhaust with just a bigger combustion chamber. Is that wrong? If I had them milled, would that make it more worth it? I can get a STEAL on a set of these heads ($300), am I just dreaming that these would be worth it? Should I just spend my money on ported ls6 heads, or is the price good enough on these that I should do it?
BTW, it is a nitrous car and I plan on spraying a 200 shot.

98Raptor

Go with ported 5.3 heads.

ktmrider

Only real advantage to using them on your LS1 is to lower the compression for FI. Otherwise spend the money elsewhere. BTW, tho, awesome price on those #317's!