Conversion to CNG or LPG

I've got a smog test coming up on my 91 740 Wagon/Regina engine, here in
California, and I'm wondering whether I'll pass. It was just marginal
last time.

Are there CNG or LPG conversion out there that won't break the bank, and
will be reliable?

 

Thanks. I was also looking for a way to go "greener", but your response
makes sense. And I don't even know if there will be a problem. Put a
new cat converter in 4 years ago. Just put new cap and rotor in.

I'll see. Thanks again.

 

converting to CNG or LPG seems like a rather expensive way to get around
emissions testing!... would probably be much cheaper to do the usual things:

new air filter
new spark plugs
maybe new plug wires, distributor cap, rotor
oxygen sensor
catalytic converter

If you or a friend can do the work, the parts are quite inexpensive.

 

Just do a tuneup and hope for the best. With everything set up right these
cars should pass with no problem.

 

Well, California is more stringent. And its a Regina system. And, I
have little data to work with and am prone to worry. I just want to
milk as much as I can out of that car. I bought it for the long haul.
Got 260k on it now. I think its good for that much more. Hate to see
it sidelined for something not its fault. I'm getting positively,
sentimentally anthropomorphic, ain't I?

 

It shouldn't really deteriorate though, if the compression is decent, the
injectors are clean, timing is correct (don't think you can adjust that) and
you don't have vacuum or exhaust leaks, the emissions should be as clean as
new.

 

I'm more worried about the guidelines getting more stringent.

 

Aren't older cars grandfathered in? At least here in WA, if you take it to a
certified shop and spend a certain amount of money and still can't make it
pass, you can get an exemption.

 

Pre-1975 are grandfathered as antiques. Here you get a $500 assistance
to make it work, but not sure what happens after that. Probably get an
exemption then.