Do Webers "like" higher or lower compression engines? Part 2 of the question is what constitutes hign and low compression as it relates to Webers?
The K code engine I had the. Webers on had a measured CR of 10.0:1. Detuning a car by lowering the CR would be shooting yourself the foot. The Webers do more than just provide eye candy. Properly set up you will see improvements in torque and horsepower. Lowering the CR will only serve to minimize or negate those gains?
The following chart may interest you, it was copied from the 1965 Ford High Performance Catalog (for ordering thru Ford dealers)
Quote from the catalog:
"Horsepower Figures were obtained from actual dynometer test programs by Shelby-American Inc."
Stock 289 w/ one 4V 232 @ 5,500 rpm (A code I'm supposing)
289 Performance 4v kit 286 @ 6,500 rpm (I think the carb is a Holley 715 w/ the Cobra Hi Rise manifold.
289 w/ two 4V carbs kit. 276 @ 6,000 rpm
289 w/ three 2V carbs kit 314 @. 6,500 rpm
289 w/ four 2V carbs (Weber 48 IDA carbs) kit 345 @ 6,500 rpm
The only thing that bothers me with running Webers is the lack of a filter. Sucking crap in the engine is troublesome and risky IMO.
I ran my 48 IDA set for 2 1/2 years, and over 20,000 miles. Most of time I used some screens that Jim Inglese sells. They are not just the just plain mesh, they filter down to 10 microns or some ridiculously small number. I tried running without them on occasion and really couldn't tell a difference in performance. I was using two AEM a/f meters, and their readings didn't change whether the screens were in or not. So I'd question Jim and try those same filters. I had occasion to drop the oil pan to fix a leak, and also changed a head gasket.. After 20,000+ miles, no measurable wear. I took that car a few long-ish trips of 1,000 miles round trip. It performed great on the highway with the Webers. The torque improvement made passing slower cars a real treat.
For cars requiring vacuum for things like brakes, will plumbing the cobra weber intake provide enough vacuum for the brakes?
You can either get an electric vacuum, or use a Weber manifold that has a sealed off plenum, in which all 8 cylinders are connected to via a small drilled hole in the runner. I used that type of manifold so I could run a PCV valve. I wasn't too keen on all the cylinders having a connective plenum, as it seemed that was negating the benefits of a IR manifold. So I did experiment with plugging up the connecting holes and shutting off the plenum, and just having an open breather w/o a PCV valve. I couldn't really feel any performance difference, and the a/f meters displays were unchanged one way or the other, I so unplugged the holes and went back to using the plenum acting as a vacuum source for the PCV system.
I don't think you can get a plenum manifold in the dual waterneck style, not sure about that.
Z
PS. BTW, I had a permanently installed vacuum gauge, and had 10" vacuum with my Webers.