Originally Posted by Annaliese:
but i have a 1915 engine with one carb. =(
Originally Posted by beetown:
so I have a dual carb 1915. Annaliese has a single carb 1915? what am I missing? Can we have the same engine as advertised with 2 different carb systems?
A motor with one single throat carburetor will run best with a stock or very mild (Engle W100 or anything similar) cam, as too much duration will upset the carb's operation (it can't meter the fuel/air mixture properly) at lower rpm's. That said, even a 1600 is undercarbed with a single 34-3 Solex carburetor; it's small venturi (26mm?) acts as a bit of a rev limiter (very important when you're a factory trying to make a motor somewhat bulletproof) but the long intake runners aren't the best for fuel distribution. This is why dual carbs even on a stock 1600 produce more power and better throttle response.
Kaddieshack http://www.shop.kaddieshack.com/main.sc dynoed a completely stock 1600; power peaked at 50hp at 4000rpm and dropped to 48 at 4500 and 40hp at 5000rpm. With the addition of a Kadron dual carb kit and an Empi quiet pack exhaust power was now 60 at 4000rpm, 58.5 at 4500 and 55hp at 5000rpm. Adding 1.4 rockers added .070-.080" valve lift and increased the duration at 0.050" lift figure (keeping the valves open longer so the cylinders fill better) some 8 or 10 degrees and the motor now ran the same to 4000rpm, but kept on making more hp to 5400 rpm (63hp) and still registering 60 hp at 5000. IIrc, the average torque gain over the stock 1600 was about 5 ft.lbs. throughout the rpm range.
Beetown- Yes, you could have almost exactly the same engine, the only difference being the carb systems (and air conditioning compressor).
Annaliese- I know you don't want to hear this, but I really think your motor needs to be a bit bigger (the addition of a 78mm crankshaft would make it a 2165) to handle the compressor.