Steve, I called Dave and asked him to get a hold of Henry to get your head sections back, sorry I had them so long. On a good note though, I don't think they are lost. :TU: Derek
Steve, sorry its taking so long but rest assured that I am still working on getting them back. It would seem that now that Henry is half way healthy he is back to being MIA during hunting season! Not sure if he's into black powder hunting so he may be back on the grid very soon? No more "tree stands" for him, now he is using a ladder stand! I heard that and just had to shake my head and tell Dave that doesn't matter because it was the gravity that hurt him last time, not necessarily the tree stand! He really needs to be in a ground level blind but hopefully he finishes out hunting season unharmed so we can get a hold of him! Don't worry won't text you, I'll be a man and give you a call when I know something for sure.LOL Derek
Can you guys please post some pictures of the head sections? I know I'd like to see them, I'm sure there are others that would too.
I have some pictures if no one else has. I'll post them later if time permits and/or no one else gets to it first.
I will post pics. I have more pics somewhere and can take more pics of needed as I have sections here as well as the ones I shipped to Chris Skaling. He is going to be doing some iron head porting as well as the alum head porting... I can't find my pics if the exhaust cut section right now will look.
I had forgot about this thread for a minute, thanks for the bump and the reminder. I have those pics Sean, plus these. I want to say I got them from Steve Caruso, but can't remember exactly.
Yeah, something like that. All of the sections are now back at Dave's shop, I already called Steve and told him that. He doesn't need them right this moment, but he will have them within the next couple of weeks.(my X-mas present to him, lol) Maybe Steve can take some pics of them after he takes back possession? Derek
They were all yours originally Steve, from that head you passed around for slicing & dicing! :laugh::laugh::laugh:
The Intake port cut a ways show good meat on the short turn and roof! one thing I would keep in mind when porting for anything less than all out racing would be this. 1) in regards to raising the roof around the short turn however much you raise it on the common wall side only do half that much on the push rod side wall. 2)95% of the port width increase should be done on the common wall unless the push rod buldge is fully ground out and sleeved with 1/2" tubing, be it Brass or Aluminum!
First off, yes I have a flow bench and have been porting heads for over 35 years,all different make heads also! My comment on raising the port roof mostly on the common wall side ( from the mid width point of the runner on over ) is in regards to keeping the needed port velocity high for a small block street strip type motor while getting a good chunk off added air flow to take place! if you raise the full roof all the way thru the runner and on out thru the blow you will drop of velocity big time. On a race motor where the new power band is coming in above 5500 rpm that's fine, but not for anything less when we are taking motors under 365 CID. one good rule of Thumb is that your air flow increase seen percentage wise in the .200" and up lift range of your Cam should always equal or exceed your port size percentage increase, IE picking up 20 cfm for a 5% increase in port volume CC wise.
Thanks for the explanation. That makes it easier for non flow bench porters to understand. Is the velocity reduction due to a CSA increase? Care to share any #'s with the forum?
On a paired Intake port head of which the Buick is one of many, giving the air flow on the common wall a straight shot from the head flange into to the bowl in very important once you get the throat of the valve bowl percentage wise ( minimum ID) up to the needed size for your target CFM, but I am getting ahead of things here! For any given valve size if your looking for maxing out the air flow for that size valve the minimum valve to throat percentage should needs to be atleast 85%, but also port area wise you neeed to know where the minimum port area is in the head thru out the whole lenght of the Intake tract, indeed if your head gets reworked to flow more air then the chosen Manifold can flow then all you would reap would be a bit more HP, but a much smaller power band! On a head who's throat ID is about 1.75" and assuming that the throat is the minimum port area / pinch point and the chamber is not making for a shrouded condition, then that head should be flowing at least 265 cfm@28"H2O. A 1.850" throat should get minimum peak air flow numbers into the 285 cfm range, but this flow rate needs carefull shaping of the short turn when reworking iron heads to get the flow through the bowl and not go into sheer. In getting back to your question some let's look at things from the persective of a chunk of air mass entering the runner of your head. The first thing we see is the push rod buldge which at low flow rates is not a restriction , as the speed of the air mass allows it to shuffle over and tuck in behind the push rod buldge and make its way over the short turn and out through the bowl,but as we Crank open the valve more and in turn pick up the air flow rate and the port velocity things begin to change! The high speed air trying to get around the buldge now compresses to make its way around it and does not expand back out to make its way over the push rod side of the port until much latter down the lenght of the runner , so in effect a velocity increase has made the port area before the short turn act smaller . to better use the port area we do have the port needs to be as wide as can safely be done by means of moving over the common wall and to raise the roof only from the outlet side of the push rod buldge on a straight shot to the crown / apex of the short turn . The best thing to do of course is to reduce the pinch in of the push rod buldge provided that the motors targe HP needs that much port area. One thing is cut in stone here, that being nothing will slow down how fast a motor revs and comes into the Cams power band than too little port velocity due to you much port area! I gotta go for now!
Another good basic primer for the pocket port guys. Good explanation. I was hoping to probe deeper into the limitations of the casting so that the guys who have iron heads and time might be able to push things to a more serious capability, maybe for a sleeper or expendable build. I appreciate the reasons you offer the opinion on powerband and caution folks on the dangers of too much port area...but I'm still asking the same questions. There's been some conjecture about the validity of #'s when it comes to the sbb head getting near the 265cfm range, so I was curious on your opinion to that, SteveM. I know that on other makes heads for example, I can pretty much look at it and have a good idea of it's potential before I flow it, and some velocity probing quickly tells the tale. The first thing I see when looking at the head section is the potential to cut out the roof to raise it (and the VC rail), and consider shortening of the head bolt boss to use a SHCS and 'port intruder' to fill the area on top of it...we are talking dreamland here of course because you know as well as I how quickly one gives away their labor time working with these iron heads. Some heads lend themselves well to this using the common wall layout, Pontiac and sbc come to mind. The so called weak Pontiac head easily has potential for 320+ with raised ports. Know of anyone that's taken one this far with a 350 Buick ? [For clarity...port intruder mainly a benefit on sbc heads, not so much others. Obviously, port epoxy used where needed]
