12a engine in a 929 coupe

[stroker250]

Hello All,
       just bought a donor rx7 (1983) with a standard 12a engine to use for parts on my 1974 929 coupe. I\'ve had the engine running, and it all seems healthy. No scary noises and no smoke, so I\'m just going to put it in and use it. It\'s on 85000m, which I understand is nothing much for a rotary .... Now, once I\'m satisfied it\'s not going to explode, I\'d like to make it a bit fitter still. Can anyone recommend a carb for it ? It\'s got a fair sized bore exhaust in stainless that came with the car, but it\'s the standard Nikki carb ... I understand the 12a responds well to a bigger carb (something like 10-15% increase in bhp and torque) but which one ? Also what about the manifold ? Do I use the std one with an adaptor plate, or are aftermarket ones available ? I can\'t find anything but contradiction on the internurd ....

Also, from the donor rx7, I\'ll have a load of spares that I won\'t be using on the 929, like doors, bonnet, wings, rear glass, wheels, seats, interior trim etc .... If anyone has an 1983 car in need of spares, let me know what you want, and I\'ll go look on the car to see if what I have is any use to you .....

cheers all

stroker250

[travellinbob]

hey, sounds like a cool project. If the 12a is standard then you might have more luck modifying it to have mechanical secondaries instead of vacuum secondaries.  But I guess if you wanted to go down the usual route and fit a 48mm down draft weber to it, but might be a tad overkill on standard engine.
 Watcha doing with the differential out of the 7. Not too suer on widths but it might fit under your 929,  after changing over the spring mounts etc.
 Other things your engine would benifit from would be an elcectronic ignition if it doesnt already have one.
  good luck and keep us posted.

[travellinbob]

oh yeah also if you choose to go weber then you can get a manifold to suit but if you choose to modify the standard carby then the stabdard manifold could also do with port matching.
 cheers.

[MikeLMR]

plenty of options with the carb

Uprated Nikki - A couple of people on the US forums have set up building hopped up Nikki\'s + some guys in Aus. Probably not that hard to do it yourself if you feel like experimenting.

Weber DCOE or Dellorto DHLA  - Racing beat do a kit and a couple of places do manifolds

Weber IDA - probably the most popular carb for big power output carb\'ed rotaries, yet again a few places make manifolds.

Holley 4 barrel - Racing beat do a kit ... probably because its american and very cheap over there. + it retains the standard 4 choke/secondary setup

Twin DCOE\'s - TWM did make a manifold but no longer in production

Twin SU\'s - Hurley used to make a manifold

or you could go for EFI and use a megasquirt (the way i\'m going)  or other ECU, again loads of choices.

[stroker250]

Many thanks for the replies . I know what to scour e-bay for over the coming months (the chassis is still under repair, one hole at a time .... this could be the world\'s first chassis made entirely out of weld !!)) so I\'ve plenty of time to get sorted for a carb. Sounds like the Weber or Dellorto (basically the same) will be odds-on favourites ... I can get rebuild parts & jets for them by opening my garage door (used a set of Dellorto\'s before on a Ford, but they were twin 40\'s ...still got the bits somewhere ....)
I\'m going to try and convert the axle to leaf spring if I can. It should be a case of welding a couple of spring saddles to the beam off the 929\'s axle.  I want to use the axle because the brakes are bigger on the 7\'s hubs. Maybe once I get it all to bits I can mix & match parts .. The axles look very similar, and the diff cover is identical, so here\'s hoping .....

I\'ll keep you updated as to progress, disasters and eaxctly when I lose patience and set fire to the whole lot .......

thanks for the help. I\'m sure I\'ll be asking more dumb-ass questions before this mutt is ready for it\'s MOT ....:rolleyes: