the heads. I am porting a set for my self and it really bothers me about how thick the wall is surounding the pushrod section.(theplace were is bulges out in the head and makes it curve) well I was wonder how thin I can make these walls because I know for a fact that shizzz is killing my air flow.

 

Are you gasket matching them or just tearing into them?

 

i gasket matched but it just looks like there could be more done. even if it requires to trim the gasket

 

Oh, I consider 30-40 thou to be a same min. Killing air flow? I take it, you have done extensive, and effective bowl, chamber, throat work, and work in the port post of the pushrod restriction area, to cause that area to be a restriction.

 

Exactly what I was thinking. You have to have damn effective bowls, seats, valves, cc's before the pushrod section of the intake port beomes a restriction! That part of the of the port is hardly the least effecient or smallest cross section.

If you do break through, and many do, you can also have it welded back up. I know some people may disagree with me but I wouldn't fret too much over it. The roofside nearest the adjacent port, overall shape, and transitions are more important things to sweat over, IMO. Bowls and seats come first, you can spend less and less time as you move your way back towards the intake manifold.

 

yes I have done very good bowl work, and chamber I just want the max out of these lt1 heads i want to hit somewhere in the 270ish and up cfm. tring to accomplish this would have been easier if i would have bought lt4s. but I know its possible.

 

Well then, in lieu of the resident porting pros responding, I'll state the following. The better way to patch up an area that you break thru porting, is to not break thru. Ya, I'm talking smart here, cuz I use a height gage to check what I have for stock to remove, and determine what is available to remove. So, worrying about how to repair, is not an issue. So, you are back to my original post, regarding min. The alternative is to use offset solid lifters that will allow resetting the wall closer to the push rod.

 

yea this is my 3rd set of heads the first two flowed terrible but I was learning I got a few tips from some pros and now i think I can max this puppys out. as for you comnet on the gauges I have been using a micrometer(I think i spelt that wrong) see I am kinda cocenerned about flow but the thing that bothers me is that I dont want to cut it down to much to the point that it will heat crack due to being to thin. but any ways thanks for the replys and if you have any more tips you would mind sharing I would love to hear them. knowledge on how to make heads flow are very valuable.

 

Ya, you spelled 'mic' correctly, however, a mic will not work to check port thickness. For someone without a height gage, (about 99.9% of people) you'll need a hermathrodite calipers, or use of a special thickness checking gauge to get into that area. Electronic thickness checking equipment is not practical/overkill for most everyday porting use.

As for thickness and cracking concern, recall those that port, that end up too thin in some areas, the areas that break thru and get welded up. Now, how thin are those areas that do NOT break thru? It takes less than a 1/32" to NOT show signs of being too thin. Do these areas end up cracking? Another area of concern for thickness, is the area tangent/adjacent to the head bolt hole. FFT.