What is involved in J-Bridging? I talked to a guy a mazdatrix and he said that its just a bigbridge port but you cut in the coolant seal groove and just cut the seal at each end and put hylomar down around the rest.Wouldent this cause a big coolant leak? could some of you give me some help, maybe a pic?



David

so that j-port isnt all that great then if it cause coolant leakin an all that other stuff

im not sure that it does, but i cant see how it wont

you silicon the ends of the water seal. it will be ok like that for about 9-12months and then it will usually start leaking water

The "monster" port and the "J" bridge port are not the same thing.



The "J" bridge port is cut through the iron to the front wall of the water "O" ring groove. So if the rotor housing is not filled with Devcon Plastic Aluminum, there will be only the width of the front wall of the "O" ring groove to seal out any coolant. Just a bead of silicone or whatever to hold back the water. It generally lasts a racing season and even when it does leak, so little water can get through the mechanical joint that it is just not a factor.



No power below 6,000 RPM. Max power above 9,000 RPM



This is used where the rules do not permit the addition of any material to the engines.



The monster port involves cutting the port runner well passed the the "O" ring groove. The only way this can work is to fill the adjoining section of the rotor housing with Plastic Aluminum. Otherwise the coolant would just run into the engine. So where there is no coolant, there is no leakage. The Epoxy material forms one wall of the runner, and the opening into the chamber is extended into the face of the rotor housing.



It will have similar port timing as a periphery port. Useless on the street. Very high idle speeds. No power below 6,500 RPM. Max power above 9,000 RPM.



Both require a very free flowing muffler. Very loud, just under 103 DB.



Lynn E. Hanover

yeah todds car would have trouble cold starting but other wise ran great.



103 is quiet! our its car is 122, its insanely loud, we need a new exhaust

I cannot, in words, do this justice. So I took some pictures of a "J" ported piece of iron with some arrows to held show some features. This port runs well but I made a mistake in extending the closing point and made the transition from the top end of the bridge to the cutoff line. I made it a bit too gradual and as a result, the trailing end of the side seal runs into the edge of the bridge and has rolled up a burr on it. It also rounded off the corner of the side seal and caused it to leak a bit.



Notice that the curve across the top of the port is not correct. The outer part of the closing line should be a bit taller (later closing) than the inner. This so that the side seal gradually is pulled back onto the flat surface, with the very tip end arriving last onto the flat.



The side seal runs off of the bridge at the half way point, and remains unsupported until the rotor is closing the port. Notice the inner track (the path of the trailing end of the side seal) just runs off into the port at the top of the picture.



Notice that the leading end of the side seal is supported by the bridge. This track line demarkates the inside limit of the additional port. Stay about 1/16" from that track line. The outer limit of the additional (bridge port) is the 1/8" of iron left in place to seal out the coolant. See the two triangles. This is a 12A iron and may not be exactly the same as a 13B.



The track of the outer oil scraper is used to demarkate the inner limit of the enlarged stock port. Leave a 1/16" so that you may radius all along that wall.



You should leave the bridge face about 1/4" wide (or more). And leave the thickness close to "as cast". Very thin faces tend to wear quickly and a missed shift can crack a thin bridge. The underside of the bridge will be sharp, with the edge facing into the inlet flow. This is fine for power, but sharp edges invite cracks. So I break that sharp edge with some fine wet and dry paper. There is no place for a sharp edge anywhere in the engine.



So that leaves only the closing point line to be copied from a template, or pattern you have made from a piece of iron from a good running engine. Or you can rig up a big degree wheel and lay it out yourself.



I hope that this helps out a bit.



Lynn E. Hanover

Thats good **** right there https://www.nopistons.com/forums/pub...IR#>/bigok.gif

this is good for racign clasees, when the class doesnt permit the peripheral port,if you are doign this on teh street a pport would be more reliable. just somethign to think about if you are not already aware of.