NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   Rotary Engine Building, Porting & Swaps (https://www.nopistons.com/rotary-engine-building-porting-swaps-55/)
-   -   Jb Welb Holding Up In Motor? (https://www.nopistons.com/rotary-engine-building-porting-swaps-55/jb-welb-holding-up-motor-33832/)

Silver Ninety Three 02-14-2004 10:12 PM

Well after spending like 5 hours on my 2ndary ports, SOMEONE decided that they needed to be cleaned up further and broke into the water jacket. The port is a monstrous street port and the pinhole is about 1/4" from where it closes towards the center of the rotor housing. I couldn't find any devcon at the autoparts store, just some other liquid steel stuff that wasn't recomended for coolant. I used some jb weld to fill in the pinhole. This was the front iron, so I was also able to put jb welb on the inside through the hole for the water pump gasket. I plan to let it cure for a coupkle days then sand it down smooth to the rest of the port. I considered welding it. I could probably get to the back through the hole from the water pump and put a spot weld in there. Think I should do that, or will the jb hold up? I don't have the time to report another housing.

ArmyOfOne 02-14-2004 10:36 PM

From what I hear if you clean it up real good before putting it on it will hold up very well.

kahren 02-14-2004 10:41 PM

what exactly broke ?

Silver Ninety Three 02-14-2004 10:52 PM

I'll post pics later. I extended the port up and in alot to give longer duration. The problem is you need to gradualy make it shallower or you will break into the coolant passage underneath. I was doing the final sanding and a tiny pinhole showed up where I went too far. I cleaned it with carb cleaner and dried it before putting the jb on.

Drago86 02-14-2004 11:38 PM

Welding it would probably be best, but ive had JB weld in my intake ( in the form of ghetto style pineapple inserts) for about a year with no problems. Some people do have problems though, one guy blew his motor doing the exact same ghetto pineapple thing i did when it broke off into the chamber. I think its how you mix/apply it.

Jeff20B 02-14-2004 11:48 PM

I'd say to weld it, but I don't know if the heat would mess up the crystal structure within the cast iron and possibly cause it to fatigue and leak some day. Hmm...

Judge Ito 02-15-2004 08:03 AM

I'm not going to go into JB weld details. But I could tell you Ihor if you do your homework JB weld works with out any problems what so ever and it will last for many years. I have used it with great results. They sell one that holds up to 600 degrees fahrenheit. It's called JB industro. Mazdatrix sells it. Do not weld it. Cast iron needs to be heated properly before you weld and that will cause your side housing to warp.

Judge Ito 02-15-2004 08:05 AM

I also have tips and tricks for this problem. I think I should write a "if you ported into the water jacket fix it mod"

amp 02-15-2004 08:40 AM

the standard jb has a resistance of 500..

ito.. what temps are the intake housings seeing....

banzaitoyota 02-15-2004 09:35 AM

You can order the proper DEVCON from Macmaster-Carr

Silver Ninety Three 02-15-2004 10:16 AM

I think Vosko mentioned that he had to use Devcon in his motor, and it broke. JB weld held better.

SomeGuy_sg 02-15-2004 10:43 AM


Originally Posted by Judge Ito' date='Feb 15 2004, 06:05 AM
I also have tips and tricks for this problem. I think I should write a "if you ported into the water jacket fix it mod"

Mm...that would be great for us newbies that **** **** up when we so our own porting , Judge Ito.

Silver Ninety Three 02-16-2004 09:28 PM

Its pretty hard to go too far if you are doing just a regular street port. The one I made is VERY aggressive.

Lynn E. Hanover 02-17-2004 06:27 PM


Originally Posted by Silver Ninety Three' date='Feb 14 2004, 08:12 PM
Well after spending like 5 hours on my 2ndary ports, SOMEONE decided that they needed to be cleaned up further and broke into the water jacket. The port is a monstrous street port and the pinhole is about 1/4" from where it closes towards the center of the rotor housing. I couldn't find any devcon at the autoparts store, just some other liquid steel stuff that wasn't recomended for coolant. I used some jb weld to fill in the pinhole. This was the front iron, so I was also able to put jb welb on the inside through the hole for the water pump gasket. I plan to let it cure for a coupkle days then sand it down smooth to the rest of the port. I considered welding it. I could probably get to the back through the hole from the water pump and put a spot weld in there. Think I should do that, or will the jb hold up? I don't have the time to report another housing.

I would clean the back side of the damaged area to bare metal. Use a corse sanding drum on a dremel.



Tape over the hole on the port side and lay in about 1/4 of epoxy material inside the water jacket. Make a big spot of it. Pile it on. If it was down to bare metal. If it was rough, and if it was clean. it will never leak. Just not a problem. It only ever gets hot after shut down when the engine normalizes (heat soaks). While running, the intake side is cold on a NA engine.

Silver Ninety Three 02-18-2004 10:16 PM

Here's a pic. Its not great. The jb is the grayish stuff where the port begins to close. I sanded it smooth to the rest of the port.

Silver Ninety Three 02-18-2004 10:20 PM

1 Attachment(s)
Shot ofthe backside. Coudln't really get in there with the camera but the jb weld can be seen right along the bottomline of the hole for the water pump.

Silver Ninety Three 02-18-2004 10:46 PM

port

FrostRacing 02-21-2004 06:25 PM

just happened to me today trying to get my ports to match in my int. i was just thinking just a little more then i see that little black bitch of a hole and that was it i was so pissed https://www.nopistons.com/forums/pub...1047683358.gif anyways any one have any tips for port matching?

RETed 02-22-2004 04:47 AM

This is one of the reasons why I refuse to offer porting templates.

Porting is a 3D process which goes beyond the 2D porting template.

Experienced rotary engine porting experts know what the limits of the irons are, and do their best not to induce damage or dangerous porting techniques that can compromise the engine (i.e. water jacket).







-Ted


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