j9fd3s

from https://www.nopistons.com/forums/Big-Bridge...p;hl=water+seal



Q: Big Bridge Coolant help, Bridge goes into coolant seal, what now?



A: First, drill a bunch of holes through this area in a junk iron, to get an idea of how deep the port can be without striking water. Near the closing line the port must be very shallow.



The seal groove is blocked with a roll pin or a piece of the drill pit shank used to drill the hole. A shallow hole held back from the port about 3/8". Look at your junk iron and use it as a depth tool to set you drill press stop. Lay in the seal. put a drop of silicone on the end of the seal. From that drop of silicone, seal along the outside of the seal groove on the iron on up to the other roll pin or shank piece.



So now you should have a bead of silicone from seal end to seal end along the outer seal groove wall.



Go easy on the silicone, as 98% of it will squish out when the stack is torqued up. The pins in the groove keep the seal ends from extruding into the port. So choose a pin diameter that fills the groove. Make the pin flush with the surface, and the housing will hold it in place. I can make drawings if you want them.



Turn the assembled engine over backwards a few times and rake the excess silicone out through the exhaust port.



Make the bridge wide enough to support the corner piece of the apex seal, if the center iron is not ported, assemble the engine with the corner pieces against the center iron.



Lynn E. Hanover

j9fd3s

from https://www.nopistons.com/forums/Review-Rot...p;hl=water+seal



A: (we don't need q!)



I decided that since I was cutting out a section of the inner "O" ring when building a "J" bridgeport, that the sealing was not that critical because there is only the contact between the rotor housing outboard of the now missing "O" ring and the cast iron. Only a layer of 100% GE silicone tub and tile caulk helps do the sealing.



I came across a supply of aircraft wire with a Teflon insulator and silver tinned stranded copper wire. Very nice wire.



I gave that a try in a 12A engine and used just the wire and a very small bead of silicone in the groove before pressing in the wire. I reused the black outer "O" ring by removing a small piece of the ring by cutting it through with a razor at a steep angle, and placing the joint at the top of the engine, so any leak

would then be visible. With a spot of silicone at the joint, I never had a leak. It ran a whole season. I redid the engine and ran the very same piece of wire another year. A friend of mine did the same thing but with regular Beldon 18 gage hookup wire (maybe Chinese)



He had no problems.



I had never had a problem with the stock seal, but sometimes I didn't have one when I needed to build an engine.



This is not some hop up trick. It just happens to work. If available, I would use the stock "O" ring seals.



This applies to NA 12As and early 13Bs. Inner seal only.





Lynn E. Hanover

j9fd3s

from: https://www.nopistons.com/forums/Pinning-se...p;hl=water+seal



q: so ive got a few questions, when ya talk about putting togeather a Jport engine ive heard people talk about pinning the seals(water seals) what exactly is done here?



also when porting a bp plate, (old style) how close can you take it towards the inner water seals and still retain good structual intergity of the water seal groove?



A:



For early stuff with the grooves in the rotor housing:



All of the groove is removed. Only the outer wall of the groove remains on the rotor housing to seal water out of the port. The port in the iron matches this exactly. So, if you saw the assembly into two pieces right through the port to get a top view, the port looks like a fat "J".



Since the groove is now open to the port, some method must be employed to keep the compression "O" ring from extruding into the port, when the stack is torqued up. The pros, like Drummond and others drill into the bottom of that groove just short of the port, and press in a short roll pin, to block the groove. A drop of silicone on the end of the cut down "O" ring right at the pin, and a thin coating along the outer edge of the groove wall, is all that keeps the coolant out of the port.



The monster port is the same layout, except that the whole water jacket in the rotor housing, next to the runner is filled with a good mechanical epoxy, and the runner and turn into the engine is then formed in the epoxy, where water would have been. Devcon aluminum filled epoxy works the best. Scuff up any surface you plan to epoxy. This is for near Pport performance, at high RPM.

If the seal groove is in the irons, the roll pin must be held back from the port a bit further as the iron may be quite thin. Still no problems.



In the rotor housing grooves, I just use a narrow chisel, to stand up a barb that has the sharp end point away from the runner. I then cut the end of the "O" ring at that same angle so it fits into the wedge shape of the barb when it expands.

RX200013B

this applies to 12a and early 13b's any alternatives for the 86-93 w/the seals in the plates?

Lynn E. Hanover

Just drill and tap for a 10-32 socket head screw about 3/8" back from the end of the groove where it opens into the new port.



Or a roll pin, if you like those things. Or, a piece of drill bit shank. It can be a bit smaller than the groove or a bit larger.



For drilling into tight places where the bit will hang up and break. Select one of those broken bits from the can and sharpen it right where the flutes start. So its still a bit but as short as is possible.



Then choke it up deep in the drill press chuck. Test drill a ruined iron in this same place to see how much meat you have to work with first. Then for the first or second time in your life, actually clamp the work down like you are supposed to every time. And drill the hole on a medium high speed. Oil the bit and go slow. It need not be perfect, but try for perfect every time.



Tap the hole or just tap in a roll pin. Then grind the pin down to just below flush with the iron surface.



There you are. The "O" ring groove is blocked. Assemble as normal with a bit of silicone around the pins and along the iron lip under the housing mating surface.



Here is the drawing again. Just pretend the groove is in the iron, if that is your situation.



Lynn E. Hanover

heretic

Belden wire works just fine in the '86-up engines as well.

RX200013B

can you explain what "belden wire" is exactly?

thanks

heretic

See post #2 in this thread.



http://www.napaonline.com/MasterPages/NOLM...=Wire+-+Primary



No it's not ideal, and it is finicky to work with, but if you take your engines apart frequently anyway it is a lot easier than buying seals mail-order or dealing with surly dealer parts guys who don't like having to look up boring low-profit items.



Plus it is a lot cheaper.



I have done a few engines this way after reading about it here on nopistons. The latest one has gone many, many thousands of miles with no issue. One thing I found to make it easier to work with is to assemble a "dry case" at low torque (about 5 ft-lb) to set the wire to its shape. Otherwise it is a total nightmare to get everything to stay together when stacking, even if you superglue the seals into place.



Borrowing an old trick that we use to make cylinder head O-rings, I took two lengths of standard 3/16" brake line and cut them to two lengths. Slip the wire in until it comes to the other end, and then cut. Perfect size every time.

JefeSpeed

Hey I'm planning on rebuilding my 1972 rx2 12a. I've been looking for water seal kits and I notice in general that there are almost no parts available for the engine. I was wondering why the 74-85 water seal kits won't work on the pre 74 engines. I know the grooves were on the rotor housing pre 74 but I thought they would be the same size. Is a twin distributor 12a even worth rebuilding? There is a fb with a 12a in it at the junkyard I'm thinking about just pulling instead.