I think Lynn described it best by saying you want the seal to run over the closing edge of the port like a pair of scissors (inside of the closing line to the outside). As far as how far to go up in my opinion very little is gained by going up extremely far because the angle that you grind it at has to be very shallow to avoid hitting a water passage.

 

For a street port I would stay below 60 degrees ABDC. How far up that is I have no idea. Depends on the year of the irons and primaries or secondaries. 60 degrees is what Racing Beat gives you in their street port.



So, we build a TDC finder rig. That is done in order to mark an accurate TDC on a really big degree wheel mounted on an old flywheel nut.



Then you mount a front iron in the engine stand. slip in a stationary gear, crank and rotor. Find true TDC. Mount a temporary pointer to the iron and move it to the TDC mark on the degree wheel. Move the crank and and degree wheel in the running direction to the 60 degree ABDC point and scribe a line along the rotor in your Majic marker field.



There is your closing line. I then raise the outer end of the line up a bit, and lower the inner end of the line a bit. To get a more defined closing for the side seal. The bowl is extended only to the first line, The part of the outer line that is raised is just a slight depression so the seal cannot touch there before the inner end is well onto the iron.



Read the stuff at the top of the page about porting. Fill in your profile. If you live close to Hebron Ohio, stop in and I will walk you through the whole thing.



Lynn E. Hanover

 

nah mate,im aussie.



im going to port my 13b re cosmo plates from stock to either large e/p or secondary bp with e/p primaries.i have a 500rwhp+ capable setup as is,just re doing the engine for more airflow b4 i get it back together.



i will search around and see if i can find out some how to stuff on setting up a degree wheel.

 

ITO, you should have just sold the man a template........

 

Finally decided on a new shape after mapping out seal travel. I built the motor and finally got it fired up.



Thanks again for everyones help!!!



http://www.youtube.com/watch?v=_OqpVQN_eJo&feature=user