Theoretically, the smog pump is supposed to add additional oxygen, so unburnt
fuel will burn (with the added O2) in the cat. So I'm told. I always thought
the same way as you until told this, and it makes sense both ways...
1980 Triumph TR7 Convertible: 30th Anniversary Edition
Member, Central Pennsylvania Triumph Club
-- Hosting the 1997 VTR Regionals!
From: Tony Robinson[SMTP:firstname.lastname@example.org.Edu]
Sent: Fri, Jun 14, 96 4:50 AM
Subject: Re: Sports exhaust on Calif. TR6
>>> My question is: I see so many older and even new cars with obviously
>>> modified exhaust systems. Whats the catch here? How can *they*
>>> get away with it? Can I change to a *sportier* exhaust system and
>>> still pass the smog exam?
>I have headers and a SuperTrapp muffler on my TR-6. My secret is to pick
>a sympathetic smog mechanic who just puts me on the machine and I pass.
>Since there's not catalytic converter and no EGR on '72s,
>the exhaust system is pretty much irrelevant, smog-wise.
The solution is really quite simple.
If your vehicle is equipped with a smog pump and EGR system, and you
want to add headers, it is not difficult to put a cat.conv. just below
Second step is to drill a hole in the collector for welding a fitting
for the EGR tube.
Although, in my opinion, a smog pump, which actually just pumps fresh
air into the exhaust is a cruel hoax by auto manufacturers. It reduces
the % of CO and hydrocarbons by merely pumping in additional quantities of
raw air. Thus, fooling test equipment into thinking that solid emissions
comprize a smaller % of the total exhaust gases.
And of course, we all think that the expensive smog pump does us some good.