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Sorry i feal i will have people stating dont post duplicate posts, have seen post on this and people are stating 2.55", 2.5 and 3".
So i have a 1993 Jap import RX7 FD3S, stock exhaust with a Blitz backbox. Its loud and found out my cat is smashed up by last owner. I have replacement OEM coming later this week, what size gaskets do the OEM cat system use please.
Contacted a few sellers on eBay stating 2.5" and when i ask, they state it wont fit.
Also the airpump gasket, what size is this... not that ill be able to find one online.
I am thinking plan B - make my own gasket, Plan C - instant gasket sealer, would like to run with plan A.
Hi, Thanks for the reply, so im in the UK and this site states End May, Start June for del. haha. Found this uk site, looks to be the correct one, https://www.autodoc.co.uk/hjs/1949867
I think if you go on their web page it will have the specs for the bolt spacing and hole size. If that same gasket isn't available in the UK you can use those specs to find one that is.
Some of the OEM gaskets are on the small side, worth having the larger hole size if you upgrade components. Also this gasket is very high quality and reasonably priced.
Contacted the seller and are unsure but OEM part numbers seem ok, worth a try. Ill purchase so gasket RTV also just in case so i can at least drive my car finally, will order the correct ones as when i get it off, can take measurements.
Do you have the dimensions now? I found a bunch of aftermarket suppliers for the two exhaust gaskets (RF36-40-305), but can't find anything to fit the air pump (N3A7-40-307). Or shouldn't it be that hot on the air pump connector? Then I could cut myself one out of paper or Burasil.
I've a new aftermarket catalytic converter, but this one comes without gaskets, only two screws...
Do you have the dimensions now? I found a bunch of aftermarket suppliers for the two exhaust gaskets (RF36-40-305), but can't find anything to fit the air pump (N3A7-40-307). Or shouldn't it be that hot on the air pump connector? Then I could cut myself one out of paper or Burasil.
I've a new aftermarket catalytic converter, but this one comes without gaskets, only two screws...
Not that hot, but I'd still make sure gasket material is rated for medium/high temps, just in case. I've a silicon hose directly connected to that tube, no problems so far.
Not that hot, but I'd still make sure gasket material is rated for medium/high temps, just in case. I've a silicon hose directly connected to that tube, no problems so far.
+1 sometimes air pump air goes in there, the rest of the time its just next to something hot.
In the meanwhile I changed it. I used this one, which is the only one to get in Europe: https://bmcats.com/de/catalogue/details/BM90188/
It's very cheap, not well welded and has a second connector, which is unnecessary and has to be sealed.
In the US you have this alternative with one air pump connector https://www.magnaflow.com/products/2...ytic-converter
Both come with a ceramic core, so let's see how long it will last!
The Magnaflow seems to come with two gaskets and my one from BM catalysts comes without them. It's no big deal to find gaskets for the exhaust and engine side, this is the OEM number for them: 2x N3F1-20-600C
You still need the gasket for the air pump and this one is not produced anymore by Mazda or any other manufacturer in my country.
So I ordered a plate to make my own gasket, drilled the holes first, then cutted it out with a disc grinder and a Dremel.
The unneeded second connector can be welded to close the hole or as I did, with another gasket and some metal part I found.
Seal the connector, then mount the catalytic converter. First I connected the exhaust side, then engine and afterwards the air pump, where I recognized, that the air pump connector doesn't fit in that angle.
So I bend it till it fitted and everything was okay without a tension.
Now I can say, the old one was really worn and now the car pushes and smells better.
Overall I can say, get your old catalytic converter to your local workshop, let them cut it out and weld a sports catalyst with a metal core in it, that meets your local emission regulations or let them make the full piping out of stainless steel.
I attached a DIN A4 PDF with the right dimensions, if you need to cut out the gasket for the air pump and the other one.
The gasket for the air pump needs a very small hole in the middle, I used a 2mm drill bit. Left one is the old original gasket and the right one is mine. This gasket is for the unnecessary second connector and the top one is a metal part I found and cutted in a similar shape. Seal the second connector. The air pump connector from the catalytic converter was heading more to the top, so I bend it down to fit it.
