Backfiring and Stalling?

[Kiloengineer]

As an update, I am waiting for parts to fix up the manifolds - the exhaust manifold was cracked and the intake may have had a gasket leak. Then I will try a new condensor. I have also checked the fuel pick-up and adjusted the tappets. If none of that works I guess I start shopping for a new carb.

[Kiloengineer]

So this weekend I replaced the condensor (again), installed a good coil out of my Jaguar, replaced the exhaust manifold and the intake manifold gaskets, adjusted the tappets, checked the timing, checked the fuel pick up line, replaced the fuel line from the pump to the Zenith carb, replaced the wiring to the coil. It still idles great but has now power and spits and backfies under power. I am using plain clear hose for the vacuum line to the distributor, could that be an issue? I ordered a new line but it didn't arrive. Unless anybody has a good idea I will take printjunky's and terriann's advice and find a new carb. After spending so much time on the Zenith and using a Genuine rebuilt kit I thought I could save it....

[73series88]

get rid of te zenith and throwon a new weber.
had an old solex. rebuilt of but was still an issue
new weber fixed all that right up.
aaron

[bmohan55]

I vote Rochester....

TerriAnn has a great writeup on the various options

[Kiloengineer]

Here I am again, sorry if you are getting tired of hearing this. Today I bought a new weber, installed it and still have the same issue. Zero power up any kind of a uphill grade. Idles fine. So to summarize, I have a new Genuine Lucas 45D distributor (I found that the (new) points were not contacting so I thoroughly filed, cleaned and gapped them). I replaced the new condensor with another new one. New plugs and wires. New carb, replaced the vacuum advance hose twice. New exhaust manifold and intake gaskets. Checked the fuel pickup line for any clogs. Adjusted the valves. Ran a compression test - all ok. The only thing left is the fuel pump - there is always fuel in the filter but only about half full (this filter is new with the Weber). Or I worry about the gas hese days with 10% ethanol, but then I suspect I would hear about that issue elsewhere. Any other ideas beside a new fuel pump? My checkbook is running on empty. Thanks.

[jonnyc]

Tried everything, no change. My last resort was to try and fix the stripped air horn/top cover that I swapped out. A little JBWeld and 2 days later, it is now on and the idle has smoothed out. Weatherman says it will be over 60 tomorrow, so I'll spend the afternoon trying to get it all dialed-in and solve the old original problem I wanted to fix in the first place. First though, I'll have to fix the vac. gauge connection I broke today.
It's always something in Rover World!

[jonnyc]

Everything is sealed up tight, old airhorn is fixed and back on, mix and standing idle are good. Back to driving it, but the backfiring when decelerating is still there, and the idle sometimes drops right out and I stall when coming to a stop, or it stays high and won't drop down to driving idle. I have ordered new carb return springs (the straight one and the bell-crank), hoping that will steady the linkage and allow me to set the idle right.
What have I overlooked?
What should I revisit?

To add; vac. holds steady around 19-20.

[SafeAirOne]

Backfiring during deceleration suggests a leak at the exhaust manifold or downpipe that introduces fresh oxygen to the still-combustable, very hot exhaust gasses.

[jonnyc]

Actually went to order the exhaust system today, but was told to try adjusting the valves first. I'll try the valves and springs first. Hopefully those will seal the deal.

[SafeAirOne]

Actually went to order the exhaust system today.

Why? Is yours bad?