To all Weber experts:

I've recently gotten my 78 B with newly acquired (used) Weber running. It starts great, idles fine, but excellerates very poorly. If I SLOWLY push on the accelerator, she revs great, but if I quickly blip the throttle, she bogs down, coughs, and backfires. Eventually it'll rev up. I don't think it's the secondary throttle, since it happens before that engages.

I've done simple cleaning, but no major overhaul (kit is on it's way). Are the jets a factor? I remember somone (Tom I think) saying make sure they're in the right order. How can I tell? One is obviously bigger than the other. Also, does the water heater make a big difference? A guy at WEBERCARBERATORS.COM said if the manifold didn't have water hoses running into it, it'll cause bad performance in cold weather. I didn't have it on because it didn't fit with the exhaust, but a few minutes at a grinder solved that. I'm also in Dallas, which right now it's more like late spring.

Any help would more than be appreciated!

p.s. it's a manual choke

Well I am no expert but I will trhow in my 2 cents. As far as the Water heater thing I dont know (I was going to ask the same question on the board). As far as having the jets in the right order they should be numbered. A small number will appear on the side of the jet (only visible when the jet is removed). Mine are a 10 and a 14. The higher number should be on the secondary throttle side (giving more gas at high throttle). Best advice is to buy the Weber Carb book. I got mine at a local retailer for 16.99 and it has been worth all that plus some. I am currently rebuilding 2 Weber downdrafts and almost all my questions have been addressed in the book. The poor performance could be caused by a bad float/float valve assembly. If the float chamber is not filling properly it will cause the problem you have described.

The heater that runs under the manifold shouldn't be needed in your area. I am in Memphis and do not use them. Check to make sure your accelerator pump is squirting a good stream into the primery.

I copied the following discussion from http://www.mgbmga.com/tech/index.html

I ran into the same problem when I installed a WEBER DGV kit but with the manual choke. I had to play with the ignition timing, the idle mixture and idle speed to get it right.
WEBER 32/36 DGV (all MGB's 1963-1980)
While a very reliable carb/manifold set up, a disadvantage with this carburetor is the fact that the primary venturi accounts for two thirds of the throttle open position (no CFM* figures are given for this position) with the secondary venturi becoming active in the final one third of throttle movement. This carburetor requires excessive initial ignition timing advance to avoid stumble on take off (if the ignition timing was retarded, we would have to open the primary throttle plate to obtain the necessary idle; this would expose the progression bleed holes which in turn would require that the idle mixture be leaned to compensate for this richer mixture condition. The end result being very little progressive richening upon further throttle opening, especially at snap throttle and so the stumble). Carburetor can be modified to allow the primary & secondary throttle plates to open simultaneously plus modifications to the progression circuit and accelerator pump at a reasonable cost. Unfortunately, the company that had provided this service no longer does so.

I have experienced the same thing in the past. The culpret is a weak accellerator pump stream, caused by a clogged fuel circuit or weak pump diaphram. I finnally rebuilt my Weber, which seemed to be running great, yet when I installed the kit, I did find, what I believe to be the float enrichment jet, or whatever the component is that is attached to the top of the carb with a plunger that runs between the floats and lifts to open/close the float bowl valve. Anyways the diaphram that actuates this plunger to be bad, it would actuate but the diaphram would slowly leak and lose its position. Anxious to see how it runs. Sorry for the remedial description, but I don't have my Weber book handy for the technical names.

I've heard accelerator pump now twice, so I'm hoping when the repair kit arrives and installed it should do the trick.
I looked for the numbers on the side of the jets. They are very difficult to read. I assume larger number means larger hole?
Don: Which book do you have? I've purchased the Haynes 3 in 1 manual on Webers, Zeniths and SU's. I couldn't find any reference to jets, other than to just make sure you keep them in the right order.
I've got the timing set to about 30 (thanks Tom for previous post).

Thanks to all the suggestions!!!!!!