About a year ago I picked up the "Parts List" 626 (http://www.stanceworks.com/2012/05/the-parts-list-joseph-dales-mazda-626-2/,http://japanesenostalgiccar.com/forum/viewtopic.php?f=5&t=15681) from Joseph Dale. I really liked how stock and clean the car was, and the simple effect of lowering it and the great wheel choice Mr. Dale had made gave the quirky little sedan that something special. The engine however, was not in perfect health.



So when I brought the Mazda home she was burning oil, and leaking from the valve cover. The compression was within 10 psi across all four cylinders, no more than 6 between adjacent cylinders. It was between 138-148 in total, factory new calls for 170. This made me think that a small amount of it was attributed to blow by, but the pcv looked original, and mazda engines are known for having poor quality valve stem seals. I put on the new PCV and was getting ready to replace the valve stem seals with a handy on engine valve spring compressor. I figured while the valve cover was off I'd clean it up, polish a thick raised band on it, and wrinkle black the rest.


VC off and cleaned.



Coated in aircraft stripper.



Stripped



Raised front band polished



Wrinkling nicely (crappy cell phone pic doesn't do it justice)




So then I find myself looking at the valvetrain....


...when I realize that the head bolts also retain the rockers and cam on this engine. Once I realized that the head had to come off to do the bit of top end maintenance I had in mind, I considered the mileage and age of the engine, priced machine work and new pistons, rings, gaskets, head bolts, etc, and realized that it wasn't too bad. So in keeping with the by and large original condition of the vehicle, I decided to go that route. So my wife helped me pull off the hood.



Then we yanked all of the accessories, manifolds, fluids, the little bit of harness there is, unbolted the transmission, starter, and engine mounts.



That's how the engine is sitting now, loads of crud in the coolant passages, sludge in the oil galleries, and it appears that there was a bit of coolant finding its way into the oil. The pistons also have seen better days. The engine leveler is attached to the block with the old head bolts, and I plan on pulling her Friday for final disassembly. The head pieces and starter are all laid out in front of my bike right now.



Here is a less than great picture of the carbon buildup/scaling on the valves, this engine has a LOT of sludge in it as well.

Any luck getting the crank out?

Dude?

Sorry, haven't had a chance to work on her at all. Pipes burst under my house, been dealing with that for the last week.

Well, after a busy few months, I've finally got time to spend some more attention on the old girl. I picked up a complete, very well running 1979 RX7 today, the body and interior are trash, but mechanically she's rock solid, starts up on the first time every time with no hiccups, shifts smoothly, has a new clutch, header, alternator, starter, tires and water pump. The plan is to yank the engine, transmission, radiator, and oil cooler next weekend, then begin the transplant process.

I had been planning on doing a rebuild of the MA, buts parts availability is very low in the states, and I'd like her to have a little more swing in her step than the stock MA can provide. The plan is to try to make the 12A look like it came in the car from the factory, and if I've done things correctly I should be able to easily retain the factory A/C, though we may have to fabricate some brackets for it.

While I like the low low stance of the car, it is incredibly far from practical while driving. So I'll be making a nice air suspension setup for her, utilizing Universal Air Aero Sport bag-over-strut bags up front, and a traditional airspring/bag setup in the rear, with all of the air management hidden in the trunk. This way I can retain the nice stance while she's parked, but be able to make a right turn with her that doesn't require using both sides of the street. I'll be sure to take a lot of pictures of the whole process.

Best thing you could do is transplant the Rx7 running gear. Im trying not to sound rude here, but the na/vc/ma engines are a complete waste of time and money. They are smokey and noisy no matter what you do. The best mazda piston engines were the tc/uc and d5s from 1300s 808s and 323s. I once made the mistake of spending money on an ma 2L in my 626 coupe when i was 21. i thought it was fast (over sized pistons, cam, webber etc) , but i now know that a 10a running on one chamber with 2 broken apex seals would have left it for dead.

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^ what restoremaz said. If it wasn't for the fact that I can get VC/MA bits for next to nothing, I'd have gone the transplant route as well.

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At least if you rotarize it, a few of us on here know the pitfalls!
As long as you realise there are NO direct bolt in bits for this conversion,
you'll be OK.

It seems like there are a lot more of these cars in Australia and New Zealand than we ever got in the states. I know a few folks down there have done rotary swaps, and I'm using a few forum threads I've seen as a loose guide. Fortunately this swap seems fairly simple and straight forward. Though I'm toying around with the idea of separating the original 626 transmission, using the tail housing, mounts, shifter, and transmission internals with the forward case and input shaft from the S1 rx7 transmission. I'm hopeful that I can avoid having to have the driveshaft extended for the swap, as that is the only part of this whole operation I'd have to outsource to a shop. My main concern is that if I do that, it may place the engine block too far back against the firewall. I don't have to worry about steering box interference since the car is left hand drive, but I'm trying keep the air conditioning and heater using factory pieces if at all possible. Hopefully the MA a/c compressor will bolt up to the 12A, or at worst I'll have to make brackets for it.

Any advice on this path, or am I going to be better off just using the complete RX7 trans and lengthening the driveshaft?

So, no advice or experience with the transmission tail housing idea?

Good news, most of my suspension goodies are showing up today, and in a couple of weeks, the wife and kids are leaving town for a month. This should allow myself and a friend to get the engine swap done as well as the suspension work. Fortunately the style of front air springs I purchased and the factory 4 link rear means that our fabrication work should be relatively simple.

Also, a few pics of the Donor car before we rip out her heart

I've done a number of rotary conversions over the years and may be able to offer some advice. The early gen. 1 Rx7 transmissions have good and bad points, so make sure it's in good shape before going through the pain of making it fit. The short overall length of the early trans make for great swaps into short wheelbase cars, they also suffer from tailshaft bushing (no rollerbearings) failure. I probably wouldn't swap the 626 tranny parts. Careful consideration required for engine setback. Try and keep the engine back as far as possible as handling will be much better. Getting the driveshaft cut is no big deal...... a poor handling car will be. I would say you'll probably do well to get the rotary running gear removed and layed out in the shop for some careful measuring. Engine/tranny mounts installed as well as the driveshaft. I'd pay close attention to the transmission tunnel and shifter placement. Typically the rotary sits high in the engine bay and requires a lot of transmission tunnel modification. Remember that the unibody gets a great deal of its strength from the tunnel to firewall area and any mods should be done with this in mind. As a side note, let me know if you want to get rid of those Rx7 tail lights....

Thanks for the advice! A lot of these are things I've already considered, but it's still appreciated. My driveshaft concern is actually having to lengthen it about 70mm, as I've seen on several aussie conversions. The 7 drives and runs perfectly, shifts very smoothly (though I often forget how sloppy an older shifter design with 34 year old bushings can be). I will probably be parting out the 7 after I'm done with the swap in the 626 though. So make sure to remind me once the engine is in and she's mobile again, should be early-mid July time frame if my 1982 CB900 cafe/brat bike build maintains its current pace, you can have first dibs on the tails.