Find yourself someone with a gas analyzer. Find out what the specs are
for your year engine in that state and tune your car to pass.
Hints:
Obviously, give it new plugs, air cleaner etc.
Raise your idle to about 1,200 to 1,500 rpm. your engine will burn fuel
more efficiently at this speed. Remember, it is the ratios of the HC O2
and CO that theys are concerned about not necessarily the quantity.
Retard your spark a bit. A retarded spark burnes more of the gasses in
the headers. I know, your saying that advancing gives you more power and
should be the way to go, but trust me, it is efficiency we are looking for.
Lean out your mixture a lot.
By adjusting these three components with a gas analyser, you can pass any
car that's not spewing oil or other big chunks.
My '80 has a weber, cam, no cat or any other form of smog stuff and I got
it to pass with flying colors. Realize that the car will be barely
driveable when it is tuned to pass. Take it easy on the way to the
testing center. When you get home with your passing grade, retune...
About the backfire... Are you sure that you mean backfire and not run-on.
If it is indeed backfire, do you back fire while driving? Could be a burned
exhaust valve or cracked seat. If it continues to run-on, you need to
lower your idle speed a little so that your weber is only pulling from
the idle circuit and not the transitionary. Purchase a $20 idle cutoff
solenoid for the idle circuit and wire it up to your ignition. This of
course is assuming that the Weber is a DGV down-draft and not a DCOE.
Pierce Manifolds has the solenoids
Good Luck,
Chris
On 21 Aug 1995, John Famolaro wrote:
> Hello
>
> I have a 77 MGB and with a webber 2 barrel carb and header. It constantly
> backfires when I turn the engine off. What should be done to stop my
> backfire problem.
>
> I also am trying to get it to pass smog in Arizona, is there a (legal)
> catalytic converter that will attach to my header. I have a smog pump for
> the car but am not sure how to hook it up with the weber carb and intake
> manifold. Is it just totally impossible or illegal to pass smog with
> replacing original carb, intake and exhaust manifolds?
>
> Please Help me!!
>
> Thanks
> John Famolaro
>
>
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