how much are my carbs worth?

911tmaster · 03-13-2002, 07:31 PM

how much are a good set of zenith 40 carbs worth? and how much is a good set of webers?

911tmaster · 03-13-2002, 09:39 PM

bump

Joeaksa · 03-13-2002, 09:41 PM

For someone doing a restoration of a car that was to be shown, the carbs might be worth something. I threw my Zeniths away when I found a set of Webers. The Zeniths were a pain in the neck compared to the Webers IMHO...

Joe

partyparty · 03-14-2002, 12:13 AM

I traded my zeniths for 4 brand new rotors and new brakes all around. Someone wanted them that bad, who am I to say no. I posted the same question a while back most people say 100 USD for each one. and those who have big money just throw them away. just do a search for "zenith" and the forum should pop up

Britwrench · 03-14-2002, 01:32 AM

Well, interestingly enough, I have a pair of brand-new Weber 40Idtp for $1500..........

911tmaster · 03-14-2002, 04:15 PM

ok is there any hop up parts for zenith carbs to make them almost as good as webers or do i have to buy webers? my car will probably never go on a track so can i make zeniths alittle better?

LR993TT · 03-14-2002, 04:21 PM

What do Webers go for today? Back in 1986 I paid $550 for a new set for a 1970 911T. The Zeniths hung on the garage wall til I threw them away.

Les

Raymond · 03-14-2002, 08:37 PM

for the record, i have zeniths on my '70T and with them atop my motor, it runs absolutely perfectly. no missing, no backfire, no stutter, no flat spots, no smoke, perfect idle... there are a ton of snobs out there that think zeniths are better for boat anchors, but i'd invite any of them to drive my car. remember these were put on by the factory, so they must work... if you don't want 'em, i'll take 'em.

jluetjen · jluetjen's Garage

Zeniths can be great -- as long as you are running them on an unmodified "T". If my memory is correct, they have 30mm venturi's permenantly installed. As soon as you start increasing the HP, you'll find that 30 mm chokes off the top end of the rev range. According to the Weber's data and formulae that I've seen, in an application such as Porsche's (1 choke/cylinder on an individual runner manifold) 30mm venturi's are good for about about 350 cc's per cylinder (or a Porsche 2.1 liter motor) with a 6000 RPM rev limit for a "racing" motor. If you want to be able to rev it to 8000 RPM (think 906 camshaft) your limited to a 210 cc cylinder or a 1.2 liter six cylinder. BA uses the formula: Venturi size (mm) = 20 * sqrt((Cylinder volume in cc's/1000) * (Peak HP RPM/1000)). So if you wanted to put carb's on a 2.4E (165HP @6200 RPM), it would need sqrt(.4 * 6200/1000) = 31.5 mm venturi. A Zenith with it's 30 mm ventury would choke the motor down to producing peak HP at around 5600 RPM. That would take a lot of the fun out of that motor!

I've been told that there is also only a limited veriety of jets etc available for Zeniths. If you fit one of the existing set-up's with 30mm chokes, great! You just saved a lot of money over Webers for the same performance. But as soon as you need to start making changes, you run out of options with the Zeniths and then you have no choice except Webers or (Gasp

$$$$) PMO's.

john walker's workshop · 03-15-2002, 09:05 AM

weber venturis do slip into the zeniths. there is just a bit of up and down movement and no set screw to keep it from moving, but they don't move upwards anyway.

911tmaster · 03-17-2002, 08:57 PM

ok thanks guys