Speaking of these: https://www.bigblockmopar.nl/wp-cont..._LA_Magnum.pdf

It states that it is designed to be used with a 1.97 intake valve, instead of a 1.92 intake valve (stock). I'm wondering how that will affect the porting. This is my first go at this kinda thing. Any advice is welcome.

 

5 hundredths of an inch? Probably not much difference. Also, I wonder if the "7" was a misprint.... don't recall ever seeing that valve size.

 

It claims that following the porting template should open up around 15% extra flow (nearly 40cfm). Who knows on valve size. It's possible.

 

I looked into this awhile back as well as it seemed too cool to be true....however I didn't want to move up in valve size, just increase flow on the stock ports, so that was a bit of an issue for me. There is little information about them. On one of the few threads someone mentioned a thin wall condition in proximity to the coolant channels with Magnum heads that is created when using these. I remember reading that someone punched through by accident. Have a look search for these and see.

 

That's the main reason to use them is NOT to remove to much material. There are a lot of variables here since the pdf file is for both big block and LA/magnum. There where different castings used(depending on motor) so you need to have the correct template for the head. The magnums i think only uses like 3-4 different castings for it's entire run. I have ported my share of heads and one in particular i went to far and removed to much material. The thin spot blew threw one time under a full throttle run. What i would suggest is to either get the correct template for the head or do this: First make some divots with the carbide bit in different places where you plan to remove material. Do not remove to much because you don't know how much is there to remove. The runners are the thinnest spot so pay more attention there. This will give you a guide line to keep so you don't take off to much in any one particular spot. Since you are a novice i would do some searching and look at before and after pics of ported heads. Usually around the valve and stem need the most attention.