I'm having the darndest time with this carter BBD 2 barrel I put on my nash met with a 1 to 2 barrel adapter. It immediately revs up to maximum RPMs when started (yes the linkage allows everything to close). The tips of both the idle mixture screws were broken off inside the carb when I took them out to check them. (the carb is brand new) Any help would be greatly appreciated!
First question I have is why did you change the carb?what was wrong with the original? As far as revving on startup sounds like you have a major air leak.
I second the post above by steinauge. And ALL of the testing we have done with either a 2->1 adapter or a 1->2 adapter have proved the conversion gives major issues! We finally got a 1->2 to come within maybe 75 percent of the original by using a carburetor that flowed almost twice the CFM of the original and an adapter with formed channels at least 6 inches long. Jon.
If your Metropolitan still has the 1200cc Austin motor, I would fit an SU carb on a "swan neck" adapter if I was going to change to anything else from the original carb.
I would think you changed the carb for more performance, right? The broken adjustment screws will need to be replaced, can you send the carb back? you said it was new. But air must be getting past the throttle butterflies some way, Look for vacuum leak.
Broken new parts. Send it back or get it repaired before trying again. I would not waste time trying to get a broken part to work unless stuck on the side of the road.
Major vacuum leak around throttle butterflies. Someone evidently tightened the idle screws in an effort to get to idle speed... Wonder if the carb mfr. had a 'flow bench' for Q.C. of carbs...and the 'new guy' was final prepping, "Aw, the buyer can sort this thing out..." Stranger things have happened...
update: fixed the revving issue and took it out for a spin. Drives better than it ever has and doesn't bog down. Much better response than the Zenith.
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