Would dual side draft Weber 40mm DCOM's be too much for an 85s... with a 12a stock port and the full RB street exhaust?

 

If you use the correct venturi sizes you should be ok.

 

Would you know those venturi sizes?

 

No sorry, not real hip on the weber carbs. Do a search for "lake cities" on here. They make the side draft manifold for that setup from what I remember. Thats might yield more info for you.

 

Another alternative: I built a mildly ported 12A for my 84GSL. I then installed an RX4/Cosmo/REPU carb. I used two of the RX4 manifold spacers(plastic) and a piece of aluminum plate to fabricate a simple adapter, then blended the bores with a die grinder. Racing Beat header, stock muffler, no cats. Measured 130hp at the wheels. Loud, but runs like a stock one until I put the hammer down.

Everybody wants to spend money on Webers, Holleys, or Dellortos. I like the stock carbs because they start and run well, hot or cold. If yours is for everyday driving, I would consider this. Mazda actually built a few RX3s with this carb, but they are pretty rare.

 

If by too much you mean too much money then I have to say yes. I wouldn't get a weber just for the fact that they are so freaking expensive.

But they are proabably perfect for you car, if cost is of no issue. Webers supposedly work very well with rotaries.