Reply to "351c Weber"

To Gorans reply, I'll add a few personal experiences with Webers:
the exact jetting on any engine will vary wildly depending on the engine parameters, the area you drive in and what carbs you have. Weber built many variations of each type and by now, most have been thoroughly molested. I once sold a set for a Pantera (off a Cobra) that had one carb with a model # even Weber-Italy couldn't trace! Note 1- all the idle, main, hi-speed and acceleration circuits in a Weber carb interact to an extent, and there are 5 jets and two air-bleeds per cylinder. The cheapest replacement jet is about $5, so fumbling around in there can get very expensive. If you've never done these before, be prepared for a steep, frustrating $$$ learning curve. I'd go to a Weber specialist. Being poor, I did a full-power plug-chop in 3rd gear, uphill, on my way to work each day, then pulled one jet from each carb during lunch hour, soldered it up and re-drilled to a different size using a set of pin-drills I carried with me. Then I'd do another plug-chop on the way home. Once I had a size for that jet that worked well, I'd order a new jet of the size my drilling indicated was OK. It took me 6 months to get the things working right. Typical bolt-on Webers either run great but give 8 mpg, or run lousey & give decent gas mileage. Second note- do NOT let anyone talk you into running foam air cleaners on Weber carbs. Webers are always on I.R intakes & there are severe pulsation effects with IR intakes. The pulses also carry fuel OUT of the carb horns so gas saturates the foam. Webers always pop and backfire at low engine speeds especially when cold. This will often catch the gas-soaked foam on fire. I burned off two sets of foam cleaners before I wised up to using big paper air cleners, and worst or all, the aux venturies are zinc castings and will melt in a carb fire. Molten zinc runs down the intakes and with closed-chamber heads, there's not a lot of room inside if a valve happens to be open. The molten zinc quickly hardens & when I re-started the engine, it cracked a piston.... Third- Always carry a freon-type fire extinguisher when running Webers. A powder extinguisher caused almost as much damage to the car as the 1st fire did. Freon extinguishers are available from Pegasus Racing in WI. They aren't cheap but the powder clean-up & corrosion damage took me 3 days to overcome. Finally, be aware that the commonly-used 48 IDA carbs are undersized for a 351C, even with 4 of them. Each carb barrel flows about 220 cubic ft per minute of air to a single cylinder, while a Holley 4bbl on an open plenum intake flows 600-750 cfm to each cylinder. So typically, a dyno run will show a drop-off of power above 5500 with well-tuned Weber 48IDA-s, just like with a small Holley. Whats actually needed are 55 IDA-s, not very available even when Weber was still making carbs. You will likely need ignition changes too since its almost impossible to run vacuum advance with Weberr carbs- the pulses mess that up. A set of well-tuned Webers look & sound terrific on a V-8, but its like living with an exotic dancer IMHO....