Well I finally, got started on porting the heads. Its pretty addicting for a first timer, even though I've had very little free time lately. I also got my comp cams valve springs (981-16) through work for $58.
I haven't done that much to them and I'm not sure exactly what else to remove. I spend the longest time working the short-side radius on the exhaust.

Should I spend about the same amount of time/ effort on the intake short-side radius?
What about the valve guide on the intake side along with shaping around the swirl?

 

Concentrate on smoothing the long-side wall opposite the short side and blending the bowl along the long-side into the roof. Do this on both the intake and exhaust because this is a high-flow area on both. On both sides you can raise the roof a little from the long-side bowl area all the way out to the gasket. Taper the valve guides down so that they are as unobtrusive as possible (but leave a little material around the valve stem for strength).

In both intake and exhaust runners concentrate on the wall that runs along on the outside wall of the cylinder (the opposite side to the swirl ramp on the intake). Smooth the transition from the roof to the walls. Taper the combustion chamber walls on an angle down to the valve seats.

 

With a 305 you want to promote as much swirl on the intake as possible because doing so directs the flow away from coming out along the cylinder wall (where the valve is shrouded) and out to the center of the cylinder ...so port along the cylinder wall side of the intake runner in the bowl area.

On the exhaust side most of the flow also flows along the outside wall/roof area, so this is where you want to concentrate your attention. You can raise the roof (but not the floor) to the gasket line at the port exit.

These general rules apply to all small blocks making power under ~6000 RPM, but for a 305 it seems to become more crucial because of potential shrouding issues. It also seems that properly prepared 305 heads are not significantly adversely affected by valve shrouding as many people have thought for some time.

 

The short-side is not a high flow area. As lift and flow velocity increases flow along the short-side radius decreases and most flow is along the roof and outside walls of both ports. Intake flow "jumps" over the short-side radius and across the back of the valve like a ski jump. On the exhaust the short-side should have as large and smooth a radius as possible because flow will not be able to follow a sharp turn at the port floor and flow throughout the port will be decreased.

If the short-side radius is rough and sharp, on either port, turbulance will be created in the bowl. This will decrease flow both at low and high lifts. Smoothing the short-side radius, therefore, promotes better flow at low, mid and high lifts, even though the short-side is not actually a region of high flow itself, and flow along the short-side radius decreases as flow velocity increases.

 

Following Casey's excellent guide, I have finished one heads exhaust side and am nearly finished with the intake on that head as well. Last night, I start cleaning the valves using a razor blade and steel wool. That work was pretty intense as carbon build up on the intake valve was up to an 1/8” thick.
Right now, I just need to figure the easiest way to clean up the roofs of the intake ports.
Hopefully I will have some more pictures later this evening.

 

Get some input from Fast355 (aka Chris). He's got the best flow #s from them, especially on the intake side.

 

I should also add that removing material from the combustion chambers decreases compression. So, unless you account for this by using pistons with less relief volume, mill the decks, or (most easily) use a thinner head gasket, then you should try to limit the amount of metal that you take out of the combustion chambers -- only grind away the minimum amount necessary for relieving valve shrouding and promoting swirl.

 

I didn't plan on taking much out of the chambers, basically just removing any sharp edges and probably polish with 120 grit. I am also going to be using a .015 thick head gasket in attempt to boost compression just a little bit.

 

The stock L03 gaskets aren't much bigger than 0.015" themselves (and have a 3.85" bore diameter), so you could actually lose a very slight amount of compression if use 0.015" gaskets with a larger than 3.85" bore diameter ...you'll probably break about even. On the other hand, the 187 heads are fairly "open" around the spark plug boss, so there really isn't much that has to be removed in the chambers. Looks like you're on the right track.

I think the 187s can actually be made into decent street performance heads for a warm 305 ...when they're done right. I'd say up to 300 hp they're probably even one of the better choices. Above that and the swirl ramp will probably hinder the flow necessary to get past 5000 rpm and 300 hp, but below that they have excellent qualities. But who knows what's ultimately possible until someone really tries to push the envelop with them. Fast355 has had some good results with swirly heads.

 

I planned on using fel pro 1094 gaskets, but are there some .015 thick gaskets with smaller bores?
My current goal is 230 hp with stock cam, exhaust, u-tbi, cleaned up intake, and ebl. Trying to push that incredibly weak link cam to the end, when it'll get swapped in the winter.
I will get some pictures up tomorrow, when I should almost be done with both heads.

 

Not that I know of. You can get custom gaskets made, but the cost will be higher. The Fel-Pro 1094 gasket should drop your compression about 5 hundreths of a point (from 9.3 down to 9.25) ...not a big deal. That loss in compression shouldn't "cost" more that a horsepower or two on a stockish L03. If you remove 2 cc of iron from the combustion chambers you'll drop your compression down to 9.0:1. Again, on a stock L03 that should cost less than 5 hp, but it's best to avoid it if possible.

Are you using the stock exhaust??? I really don't think you'll get 230 hp as long as the stock exhaust is in place ...it'll hold back almost anything you do. DIY ported heads will probably be limited to under a 20 hp gain with the stock exhaust system ...probably closer to 10 hp. At this point your exhaust is the major restriction. It doesn't matter how well your intake and heads can flow if the exhaust won't allow a proportional amount of gases to be expelled. It's simply a case of "you can't flow in more than you can flow out".

But, on the bright side, when you do change your exhaust you'll notice a huge performance increase ...then you'll see your head work, intake and exhaust all work together and really wake your motor up. You could get 230 hp then (if you did a good port job), but that would be the limit with the stock cam.

 

I didn't word that wisely last night. What I meant was with stock cam, crappy flowtech headers and y-pipe into 3" pipe, slp dual/ dual muffler, u-tbi, and ebl. I was just trying to figure what the limit would be with the stock cam.

 

Well, I think your goal is a good one ...ambitious, but not unrealistic. If you get good flow from your heads, and you have a good ECM tune, you should see about 230 hp.

Are you doing anything with your valves or seats? Valve and seat work is primarily responsible for low-lift flow gains. And since the L03 cam is perpertually low-lift your best gains would probably come from back-cutting or radiusing your valves and having a good 3-angle valve job done. The L03 cam lifts the valves slowly and not very much ...low-lift flow numbers are crucial with a cam like that. Even with a much more aggressive cam low-lift numbers contribute considerably to torque and lower-end responsiveness.

I'd definitely invest in a good valve job and back-cut valves (or DIY radiused) ...regardless of what heads you're using. I know everyone has a budget, and I don't mean to throw extra expenses at you, but this is one of those things that should take priority. I don't know what a valve job runs in your neck of the woods, but if you have the cash, and you plan on sticking with the 187 heads, now would be a good time ...and it would be a definite improvement to your head flow.