dabuzz

Why is it chicks hate these so much, I'd love one too, but mine cant stand them Anyway, I Vote LSA conversion next on the list!

Yup twin dizzy only, although, the US market had bigger single hole exhausts on their twin dizzy's much like the early single dizzy rx3 motors etc

Thanks man, yea has been good doing it over the past week or so, unfortunately I'm pretty much caught up so apart from a few smaller bits, ill have to wait until the panel is underway again before I can do some proper updates again. I'm actually inspired again, got a bit over it especially after the panel setback, but doing this log has reminded me of how far I've come with it from where it started.

And here she is in all her glory!

So to recap - here are the specs- Mazda 12a Twin dizzy bridgeported, and exhaust ported. Plates skimmed and Nitrided Rx7 6 port rotors, with 3mm carbon apex seals Cross drilled E-shaft for more oil flow Fully balanced rotating assembly High volume 12a rx7 oil pump, and FD Rx7 110psi oil regulator. All new bearings (incl torrington) seals springs gaskets, - everything possible. 48mm IDA Weber carburetor Electronic ignition conversion Modified front stack to accept oil pump and also machined later model twin pulley hub so can run twin belts

Motor assembly. All went together nicely, A couple of mods needed, I fitted a late 12a rx7 oil pump which is a higher volume unit than the twin dizzy one, the body heights are different so I had to have a custom spacer made to push the oil pump chain cog in line with the pump itself, and them machine down the cog so that the dizzy drive stayed in the same position. I also discovered that I had an oddball E-shaft in it after it was already assembled, annoying as I had a normal one on the shelf too. Turned out to be an auto shaft that was used in a few of them. The difference was the rear end of the shaft where the spigot bearing goes is a lot shallower and a different diameter to normal, this meant I had to shorten the gearbox input shaft, and instead of running a roller spigot bearing, I got a custom bronze bush made to suit, a bit of messing about, but it all worked out in the end.

Hows this, was looking through old pics and this pops up....

Onto the motor itself now. Engine plates were bridge-ported by a mate, and then I had them skimmed flat. after that I sent them off to be Nitrided (hardened) as the twin dizzy plates are notoriously soft and can wear prematurely with newer style springs and seals fitted. Part of the Nitriding process involves high heat cycling, which makes the frost plugs and bungs loose so afterwards I had to replace the frost plugs, and drill and tap in new oil gallery bungs to avoid leaking at a later stage. after that the plates need to be lapped in to remove any of the roughness left to the surface after treatment, pic of baby monitor shows males are actually capable of multi tasking after all . Housings were notched to suit the bridge, and honed by hand for a new flat surface. The factory 3 hole exhaust outlets were also opened out to make one big hole for more flow. Rotors are 12a 6 port single dizzy type, these are the lightest high compression factory rotors available, i didn't want to fully lighten the assembly, as its a street cruiser not a race car, and will aid in drivability around town. The complete rotating assembly rotors, shaft. counterweights clutch and flywheel have been fully balanced to suit Flywheel has bee custom made at 12 pounds with offset ring gear to suit the twin dizzy's unique starter position, and I am using a sprung puck clutch and heavy duty pressure plate for clamping duties.

I know this car, was in wellington with a 10a nosecone plates were 1LOWHO, a mate of mine bought it up to Auckland (Darren) and fitted the flares and BBS blacked out etc Very tidy bodywise, guard hacking aside, good score!

Not bad, often I might run a tap into a nut/bolt hole etc to be sure as some of them can get tight, no worse than a rusty scummy 40+ year old bolt anyway.

Cheers, normally 4-5 days depending on their work load, I use Terei Bros in Kelston West Auckland

Phil's rotaries in aus

Thanks, I wouldn't know if its possible to do at home, but I usually just take a small bucket load of stuff down to our local platers and it comes back nice. I love the stuff, just send in your dirty scummy rusty parts and they come back mint, zero labour and maximum effect! Also pretty cost effective really, i would estimate if you sent a whole cars worth of nuts bolts and brackets in, you'd have change out of $1000. @MRWEST agree, def hurts the wallet, but the mental thing of being so close and taking big steps back was hard to deal with. Ive always had trust issues with people working on my stuff, and this was one of the few times I've let someone take the car and it bit me, oh well lesson learned.

This would probably be my favourite part of the build, the plan was always to look mostly original, so when opening the bonnet i didn't want a shiny K&N filter sitting on the Weber IDA The solution was to modify an original air-cleaner to suit, it sits at exactly the same position as it would with a 4 barrel, so now when opening the bonnet at first glance you would think its unmodified.

Got the booster rebuilt, bought all new brake and clutch components, made up new hard-lines and had them plated, new reservoirs etc. Not pictured, basically all components have been sourced new for the bay, all that's really left to do is modify lower radiator hose 1 heater hose, and make up a wiring loom. Found an original rx2 radiator and had it re-cored and up-rated to 3 core system, have 2x electric thermo fans instead of the clutch type fan for extra cooling

bridgeport or nothing

Next was to decide how to get the best out of the motor, and really if I want the bridgeport to rev I needed a 48mm Weber IDA carb Found a rare twin dizzy IDA manifold, and a carb, then refurbished them, stripped the IDA completely, and while I was there did the internal extended fuel bowl modification, and jetted as close as possible for a 12a, will need to be adjusted once on road. Also rebuilt the alternator, adding a twin belt pulley, which is more reliable than the singles at high revs, and found a brand new starter motor, but stripped anyway to detail the same as everything else. With the twin distributors, there is nothing available to upgrade these, and some guys convert the twins to single dizzy so they can utilise the rx7 electronic distributor, but I still wanted it looking semi original. so that wasn't going to work for me.. Luckily I was able to score a custom electronic set off an old race car that uses an optical sensor, this will greatly improve high RPM performance without having to worry about points breaking down now.

In keeping with the 'factory improved' theme I'm running with, I located an old 12a twin dizzy rotary engine to rebuild. It was near complete which was a big bonus. I also pieced together a dummy block to mount into the car after sourcing the correct engine crossmember, so I could start sorting all the ancillaries etc. Stripped the motor down, cleaned up and bead blasted the alloy parts ready for modification. The last pic shows what factory improved means, more on that later, but you can see already what Ive had to deal with, its not a survivor "OG" car, i do like to see original looking cars, but rotaries to me have to sound a certain way, therefore it had to brap! so the call was made - 12a Twin dizzy bridgeport!

Gearbox! Located a factory Rx2 4 speed, and have completely stripped and replaced all bearings, synchro's, seals etc. Bead blasted the casings, clear coated them and re-plated the rest.

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Ah yea, should have mentioned that, they are off the shelf super low cobra springs, and KYB shocks, once the car is on its feet and getting close to completion I'll get the shocks shortened to suit, at the mo I already know the nose will sit too high

Couple of random pics, Front steering reco'd. Front guards and valance dipped ready for repair. Some repro badges, (beats trying to restore old parts). Restored the grille, even scored a NOS AA badge for it! Purchased a reproduction tail light valance, the guy in Aus who makes them has done a fantastic job on them, almost better than original.

Thanks, I've always dreamt of doing a nut and bolt resto, I tried many years ago on another car but I got over my head and sold it. I wont do it again either too time consuming, but I'm determined to make this build the best I possibly can.

Got sent this pic a while back from a previous owner, would be around 1996 in CHCH The guy who bought it got it off an old lady who had at some point blown up the 12a and had a 2 litre 626 piston motor fitted! there were signs of this as there are poor mods done under the floor/chassis to mount gearbox, and the wiring loom hacked to make it work. under floor work has been repaired now. Anyway, the car will be going back factory white and I like the old school feel, so I had the 'racing' stripes reproduced to be fitted at a later stage.

Re-chromed bumpers, door handles, some badges, and tail light rings etc, and also purchased a few quality repro badges, I'm not one of these guys that get hung up on everything has to be genuine, i would rather a mint re-pro than an average 40 year old part, or some hoarders Mazda taxed NOS part. imported some US spec full red tail light assemblies, and have polished them up, rear 1/4 US spec reflectors which light up as opposed to NZ type which dont. Also scored brand new lenses for the front indicator/park lights, and NOS headlights.