how do these ports look i havent scribed them or anything just drew out what i was thinking about what do you guys think

 

I would get a templat but you can go a slim bit higher on the port opening.

 

sorry if i sound really noobish right now but i am when it comes to porting, is there a link that discribes areas of the port i have looked at alot of Ito's pictures and read alot of posts about sizes i decided i wanted a street and possibly leave room for a bridge on a later rebuild. what i am wondering is what do you think about beveling the edges after you arrive at your final size ive seen pictures of it both ways and dont know if their is a advantage to it or not can some please school me on this i have not done anything to the irons and wont start untill i am certain of what im doing i have some junk ones to try out first. as far as tools i have a air pencil die grinder with adjustable speed and a set or carbide bits am i missing anything?

 

Just grinding the port bigger without a plan or a template from a known builder is like opening a Crane Cam catalogue in the closet with no lights and selecting a cam at random. It is unlikely you will enjoy the result.



The port shape is just like a cam profile. The line along the outside of the engine is the opening point line. The line across the top is the closing point line. The total area of the port opening is the same as cam lift at the valve. So if you are up on your piston engine hop ups, this will not be much of a mystery to you.



So, as in the piston engine you first decide what you want from this engine, and second, how much grief will you be willing to suffer to get that particular amount of performance. There are several thousand permutations of outcome based on supporting equipment. So for starters let us say you want this in a street car, or daily driver, and just once in a while make a fool of yourself on a closed course, out of the public view and with rescue equipment and personell standing by.



Now buy the biggest degree wheel you can find. Then find actual TDC (Top Dead Center) and varify that the wire pointer is actually pointing at TDC on the pulley. Find a chart for your engine to find the open and close events for the primary ports (the little ones in the center iron) and the secondary ports (the big ones in the end irons). Read through all of the posts on port timing. Its always in degrees (On the degree wheel) before and after the nearest TDC or BDC. Note that there are two TDCs (minimum volume) and two BDCs (maximum volume). Once you have this stuck in your mind you begine to see the 4 Otto cycles of the 4 stroke rotary engine. It is just like a piston engine. The rotor performs the function of the valves in a piston engine, but it looks like a piston port 2 cycle in port shaping and tuning. In that intake runner size, shape and length, as well as exhaust runner size, shape and length have a very big affect on performance.



So if your stock closing line on the primaries is 45 degrees ABDC you might just go up to 50 degrees or a hair more to keep the prmaries close to stock. That way you can come off the standstill with close to stock performance and still get some fuel mileage. Then move the secondaries up to 60 degrees to get some more top end. For more torque all through the range, move the open line just a bit on the primaries, and a bit more on the secondaries. The car runs out most of its life on the primaries, and the vacuum system opens the secondaries when manifold pressure gets high enough. (higher RPM and full throttle). You start off doing just a bit of porting and add more as you see what the outcome is.



Read all of the inputs on this web page and find your port events in degrees and study those. Put the die grinder down until this is all clear in your mind. Good luck.



Lynn E. Hanover