Guys,
I've torn down the 13B engine that was in my Fiat and my aim is to rebuild it. The engine came from a neighbour's 86 RX-7 that was totalled. I also installed the transmission. As far as I'm able to find out, the engine had never been opened since the car came from the factory and I found that some of the water passages had been repaired with some kind of epoxy. I have attached some pics for you to see what I'm talking about.
Now, the engine has not, in the past, given me any reason to be concerned about that, but since I've now seen the patch, I'm turning to your expertise to see if anyone else has seen this type of patch and maybe I should look at getting a different engine. What do you think?
The patch looks very professional and IF it did come from the factory that way, I think I'll put it back together the way it is.
All advice would be appreciated.
Don

 

You can't use those irons, they are totalled. At some point they cracked in a very common spot and were epoxied. Not a long term solution.

Unless the epoxy was applied as a preventative measure when the engine was assembled. Scrape it off and see what's underneath.

If you do need new irons, they are easy to come by in the Classifieds.

 

OK, since no one else replied with any different advice, I will take that to mean that everyone agrees with your assessment.
I will say, however, that the only thing the epoxy is doing is backing up the square shaped large "O" ring that keeps out coolant.
I did go through the "classifieds" and couldn't find any "irons" for sale.
I did send emails to a couple of people that had engines for sale, but they were fairly old posts and since I didn't get a reply, I imagine that they've been sold.
If anyone can help out here, it would be appreciated.
Don

 

PM sent....Help is here

 

You can post a wanted to buy and people will probably come out of the woodwork. 6 port irons are very common and almost worthless. I'd have some for your cheaply but I just sent them all to scrap.

Buying a complete engine might not be a bad idea either because it's always nice having spare parts.

 

gah aaron, i would have gladly taken a few of those irons, start collecting parts for a first engine!

 

That engine looks to have been previously tinkered with, the irons have black spray-paint on them and in 1986 I'm fairly certain Mazda was not painting them. I don't think Mazda ever painted any production car irons but don't quote me on that.

 

Nah, the paint was me cleaning things up.

 

Just remember that the repairs you see are in the highest pressure area of the rotor housing, where combustion occurs. If it was on the intake port side of the iron I would say don't worry too much about it, but being how cheap the irons are, and the added expense of gaskets if you have to tear it down again, I would just replace them now.

 

OK, I bought another engine and will tear it down to see what shape it's in. If nothing else, I will change the irons and make one good engine out of the 2.
This "new" engine has been hot rodded somewhat. Most of the emission stuff has been eliminated and if possible I would like to leave it that way. All of the "rats nest" vacuum tubing is gone and the "upper oiling system" is gone. I don't like the idea of adding stuff to my gas to provide oiling so I will probably put that back on, however I would like some comments from the guru's here on the forum about that.
I would like to end up with a dependable, smooth running engine in a small convertible that had 85 HP with the stock engine. As you can guess, I already have quite a HP increase with the rotary and so hot rodding it, while it can never have too much HP, is probably unnecessary.
As always, any help would be appreciated.
Don

 

Carbureted or EFI?

 

It's an EFI.

 

In that case, follow the emissions removal instructions for whatever series of RX-7 the engine came out of. Should be able to find them via the 2nd gen FAQ. Whatever you do, don't delete the BAC valve and cold start thermowax on the throttle body. Removing them has no benefit and just makes the engine harder to live with.