PLASTIC

[Don Dulmage <big-d@xxxxxxxxxxxx>]

They did not perfom well on the flow bench compartively speaking, but they are better than no porting and an large improvement over stock. It would appear that they were not developed on a flow bench nor were the MP heads at least up to STG6s so the tech line told me but copied from the shops work that was contracted by MP to do their heads. 
A flow bench can be a real heart breaker at first as all the stuff one thinks would work gives only minmal results. After a while you begin to nderstand what the motor wants and what is important and also what is not. Often it isnt popular but neverless it produces real results. 
Still in the absense of any other reliable method the templates are a workable idea for producing repeatable porting shapes. 
Best thing is to read the guys who are the real expets. people like John Lingenfelter, Smokey Yunick (probably the best at it ) and David Vizard. These man understood airflow in a way many others never will and it is too bad they dont know wat brand todrive but thats life. .I know  that  pretty and nice looking doesnt mean squat , the air doesnt care . With our heads the trick is to keep the air flow stable  because as soon as it starts to tumble (or run into itself )the port goes into turbulance and flows go way down sometimes even -60%. I bought a set of Direct Connection ported heads once and tested them on the flow bench. They were beautfully done and smooth and looked wonderful. Even had  anodized screw in plugs instead of frost plugs. Very nice. BUT on the flow bench once lift reached about 500 they went into turbulance and began to actually howl. In fact my wife could hear it in the house and complained of the noise. That was quite a shock to me and i was mad at my flow bench for a couple of days but then i took a head (in facts several) and began woring step by step. I still have one of those heads with every port different. Once you grind in the wrong spot it is usuauly impossible to recover the lost flow. In our heads the short side radius is the danger spot and it is sometimes better not to touch it than risk ruining it. I never pass up the chance toloo in asetof good after market heads regardles f brands. There are principles of flow  at work here and they are not brand specific. Also my Dad an engineer gave me his books on the mechanical side of engineering. Even though he is an electrical engineer back then they studied all disciplines till the last year. One book in particular caught my interest. It was the study of fluid dynamics and I have often looked in it for info.  My favourte set of heads I have ever done are on the Lemans engine (400cubic inch  Olympic Charger practice car) I did . 
They were 452 motor home castings. I also did a very similar set for Steve Sheahan of the Discovery Channel which is the last engine to leave my shop.  Not everyone will agree with me i know and that is ok. I understand that. I stand by my work though and believe what i said. All really good heads have definate similarities in the valve bowls and that is where most of the horses are tied in our heads. The ports themselves arent a real huge factor.  The biggest obtsacle to overcome is to get the vavle pocket to have flow 100% around the head of the valve. most of the time it is not. (Watch a tea pot sout as it pours , in fact watch several . You will quickly understad this. ) At low lifts the valve causes a slight restriction and keeps things in check but as lifts creep up into the above 500 zone that is no longer the case and often the short side or floor side of the intake prt will stop flowing and that air no longer akes the turn downwards but just rushes across to the far side . Often it bumps into the  air already flowing over there and the two streams get fighting with each other and flow goes out the window. That is the NUMBER 1 problem to overcome. I try to combat that by getting the port to have a bit of swirl. Others have other methods. 
Results are all that count. I always say "if you want good heads you have to think like an "air." Some will get that ,some wont.  I sold my flow bench a couple of years ago along wth all the machine shop  equipment. i built it myself from plans in SuperStock magazine . I had a head checked against my bench to a Superflow. The difference was less than 5%. Actually the guy said that was the highest flowing iron head Mopar he had ever tested but he was primarly a chevy guy so it may not really mean anything.  ) if you are into porting  a simple testing device can be made from a shop vac or leave blower. The real trick and many exerts will always tell you the same. AWAYS test your work on THE SAME BENCH IN THE SAME CONDITIONS> Warren johnson once wrote that as well in one of his NHRA newspaper columns. I know he is a chevy guy and hates us mopar guys but besides that when it comes to making power he is no fool.  I always try to make sure i dont dismiss somethig just because te competition has it or fond it. With my personality and heritage tis hard sometimes but it pays off. 
Don

 
Author of
Return to Deutschland (True Adventure)
Old Reliable (Mopar)
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