quickWS6

Okay, so we started porting my heads tonight. All we've done so far is the exhaust. Just opening up the port to match the gasket (keeping the lower part straight across), grinding down the little bump that is in there right before the stem for the valve. We're going to polish the exhaust side and I might go to bigger exhaust valves (1.60"). I plan on keeping the stock intake valves, and just polishing the intake, opening up the sides a little, and grinding down another bump that is back in the port. Any suggestions or comments on this tactic? We might polish the combustion chamber some too, but the heads were milled and they are already pretty smooth.

2000RATA

Free advise from someone with a flow bench. Since you are not going to go with larger intake valves, and a 1.60 exhaust valve won't fit on the stock seats, use you stock exhaust valve as well. You are going to pick up some flow on the intake with what you are talking about. The exhaust is going to flow way better than before if you do it right. You can achieve more than enough exhaust flow to support what your intake will flow. A good valve job will gain you alot!

mulot30th

I did this on my stock heads.... And did not sensed any significative gain from this alone... Maybe 5 hp???

I did match the exhaust gasket too (round hole) but when I received my stage II heads the exhaust port was D-Shaped, and this stage II exhaust port flows a whole lot better than my rounded exhaust port... So my advice would be rounding the upper part as well as grinding down that ridge before the valve stem and not touch the bottom part so you will end up with a D Shaped exhaust port...

quickWS6

Okay, I will stay with stock valves for now. I had a local machine shop do a valve job on it, they build monster Pro-Mod motors, so I have faith in it.

I am keeping the exhaust port D-shaped, I'm leaving the bottom part straight across and opening up the rest to the gasket.

Thanks for the tips, keep them coming!

Vents

iTrader: (9)

yeah, but pro-mod motors break alot too.. j/k man.

i've done this in my garage as well. my biggest thing with these heads as always, you do not have to open up the exhaust to match the port. simple bowl work on these heads is sufficent to support what most people want to do. anything more than that, and you start to loose torque. the exhausts sides of these heads flow very well, (consider 40+ cfm better than a mustangs e-7 intake port) and you know what HP they make on stock heads.

the intake is a diffrent story all together. i leave the valves alone, blend the casting flash around the valve seat area, work the bowl and blend it, and match the high side turn to the bowl. aside from that, smoothing the casting 80% (not 100% polished it dosent allow the air to tumble) and removing the rocker boss in the manifold side, and matching the runner to the port wall. easy as pie, just time consuming. good luck!

Red12secZ28

iTrader: (2)

I've ported a set of stock ls1 heads. It was my first time. But, I had a guy at a local shop with a flow bench help me out. Heads flowed about 290ish intake and 215 exhaust with stock valves. With the exhaust side you need to keep the bottom of the ported untouch except for blending the valve seat into the runner better. Everthing else everyone said was corrected about the exhaust port. On the intake side you do not want to take out the swirl ramp that you see when you look straight down the right side next to the valve guide. Ls1 heads are not ls6 heads!!!!! The valve angles are 1 degree different. Thats why you can take the intake the intake runner all the way to the bowl. Leave the swirl ramp. I took almost 5/16-1/2in. of material out of the roof of the intake runner. My heads literally went from 260cfm to 290cfm doing that. Remove the rocker boss and blend that real well. Do not touch the floor of the intake side,just smooth. Finally make sure you blend the valve seats into the bowl.