WTT Weber 48s for Weber (EMPI) 58s

[Ron R.]

I have a set of Weber 48s (thats 4 each) that I'd like to trade for some 58s. The motor I'm having built would be pushing the upper limits of what the 48s can flow. Mine are in great condition (only 500 mile on them, essentially as new), and I'm looking for some 58s in good working condition.

I have my own manifold, so that is not needed. I would be willing to add some cash for the right deal.

Contact me by PM or email.

 

[Cliff Beer]

Ron, you sure you need 58s? I know there's been lots of good debate on here about just what size motor webers will feed adequately but my experience has been that 48's will serve up great hp/tq on any Ford engine as big as you can build it (500+ ci).

You must have tried the larger choke sizes available, right? You can tune it to the right AFR through the rev range or no?

If a Lincoln 460ci can breath through the below carb (not saying it's optimal, but it is stock) then four big 48's should feed just about any Ford V8.

With a smaller choke v. displacement then one gets really good (ie. fast) flow and great atomization.

 

[Ron Earp]

Ron, you sure you need 58s? I know there's been lots of good debate on here about just what size motor webers will feed adequately but my experience has been that 48's will serve up great hp/tq on any Ford engine as big as you can build it (500+ ci).

Weber 48s do run out of steam though. Using the Weber sizing calculations the 48mm choke will only feed a 427 up to about 6500 RPM. A 500 or 600 inch motor will be limited with a 48mm choke.

 

[Johan]

What kind of manifold do you have ? I assume for a Ford of some description. I would like a SBC manifold as a backup as mine corrodes if I leave water in the engine.
I have the 58mm webers and they stumble when cornering unless the float level is dropped a bit from optimum dyno level.
They are very rare. The SBC setup was only fitted to Grand Sport Corvetttes and Lola T70s as far as I can tell. Mine were original to the car but I have never seen a complete setup for sale.

 

[Brian Kissel]

There is, (or was) a fellow down by Detroit, that bought some McKay stuff from me a few years ago. He told me he bought all the remaining 58mm Grand Sport stuff from GM years ago. I'll see if I can find his card.

Regards Brian

 

[Ron R.]

Guys,

This is where I am. I'm putting together (well, not me, my builder) a full roller, windsor based 393 able to spin up to 7200-7400 rpm, running something like 11-11.25:1 CR, AFR 205 Heads with some porting, a weber intake, and as aggressive a cam as I can get away with and still be sort of streetable (I don't know the exact specs, but I'm willing to put up with a lot, and will track the car).

As you probably know, flow in 48mm webers is limited by the venturi (choke), which comes stock at 44mm. You can put in 45 mm venturis without any machine work, and can put in 51.5 mm venturis with some work and parts at a cost of about $800 each (in addition to the cost of the carb). At that point, you're getting close to the cost of new aftermarket weber copies (EMPI) which can be produced in 58-60mm versions. The VW bug drag racers use these frequently.

If you look at the graph (Ron) provided, standard 48mm Webers won't really flow enough to make the most out of my engine's potential at the top end. The intake isn't the issue, and will flow plenty and fit right up to the 58mm versions. From what I've found, the general consensus is that 48s can only flow enough to make 550-600 bhp (depending on who you believe), and my motor could potentially do a bit better than that.

I'm certainly open to everyone's input, as my personal motor-building experience is not with american V8s.

Thanks for your input!

 

[Ron R.]

Oh, and just to be clear, I'm looking for IDAs, not IDFs, DCOEs etc.

 

[Ron R.]

Ron, you sure you need 58s? I know there's been lots of good debate on here about just what size motor webers will feed adequately but my experience has been that 48's will serve up great hp/tq on any Ford engine as big as you can build it (500+ ci).

You must have tried the larger choke sizes available, right? You can tune it to the right AFR through the rev range or no?

If a Lincoln 460ci can breath through the below carb (not saying it's optimal, but it is stock) then four big 48's should feed just about any Ford V8.

With a smaller choke v. displacement then one gets really good (ie. fast) flow and great atomization.

Cliff,

I bet that Lincoln got really great gas mileage.:lol: