Single DCNF viable for the street

carl

True Classic
Another topic probably discussed for ever but what is the consensus on a single DCNF on a street driven motor? I thought there was an issue of off idle or mid range stumble? I currently have a 34 DATR and in a box a pair of 40 DCNFs/manifold. The motor is a 1500 that is stock except for a 40/80 cam and a header.
 
yes and no

Carl. The single DCNF will work fine on the street with the correct manifold. But, the 40-80 cam will create problems for the idle. It will need to idle around 1200 to 1300 RPM as it will be really rough and unreliable below that. Also the old FAZA sprint intake manifold is junk because the runners are too small in order to make room for the water jackets. It really kills the power and is pretty much a waste of time. You will need to take a stock intake manifold and cut out the top and weld in a top plate that will fit the DCNF. Make sure that the area below the carb that leads into the plenum is unobstructed.

As for the duel carbs they will idle like a baby with the 40-80 cam and deliver the best of both worlds. The reason for the great idle is the elimination of reversion from the other cylinders with a IR system. Also most people think that you just doubled the carburetion with the duel carbs when you actually cut it in half. Therefore you need larger carbs with duels to get the air flow back up. The jetting can be a little problematic and make sure you have a good ignition system.

Good luck
Charlie
 
FWIW BITD

My 74 had a single 40 dcnf, with a 35/75 cam, mechanical advance distributor, air pump eliminated, supersprint exhaust. I thought it was pretty great. Didn't realize the faza intake was bogus, as I'm sure that's what I had. No internet then, alas..
 
I have 2 x DCNF 36 Main 185 jet 125 idle 45 1300 cc engine, idles perfect at 1250 o/min. Regrinded cam and 40 mm inlet and 35 exhaust valves. Stumbles a bit before main jets are activated but no problem, a bit on the lean side.
 
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