1fastz

iTrader: (16)

A buddy of mine has the hook up at a machine shop and tells me that he can get my ls1 heads to become 2.02-1.57 valve heads for very cheap, about 200 bucks. I wanna know if it is even worth porting my heads, they are i belive 853 castings (98 z28). And what kind of power will i be looking at, and what cam specs would help this heads? A bigger lift cam?

orangeapeel

iTrader: (18)

There is nothing wrong with the cam that you have. I think that a set of ported 853's (If done correctly) should yield the same power that a set of ported 241's would, and possibly close to the 243's. I would imagine like 10-20rwhp could be had. Just depends on the time spent and quality of the work. Hand port + CNC is always the better choice. Mill them too if you plan on getting them ported. You will want to have them clayed and make sure that you are not going to have a conflict with the cam you have and possibly flycut the pistons for a bigger cam in the future. Plus, you will be factoring in the new bigger valves. I am moving this to the internal section for further notes.

1fastz

iTrader: (16)

anybody else have their stock heads ported with the similiar specs?

bshell

iTrader: (24)

I have a set of stage II ported 853s (2.02 int, 1.57 exh). I had them flowed locally before I installed them and they pulled just over 300 cfm on the intake and 200 cfm on the exhaust at .600" lift. The midlift #s aren't that great when compared to other small chamber, stock valve size heads though. You also end up trading ptv clearance for the peak lift #s. This leads to problems when you try running thinner gaskets and / or having the heads milled for better compression.

If I were to do things over, I would probably go with smaller valves, mill the heads, and run a thinner gasket for better quench and compression. Hope this helps.