Can't pass emissions, Help!

[LynnJr]

Originally Posted by JellyBeanDriver

He already put in a new cat.

They work over a narrow range. He's pretty far out of range - not sure it is even contributing to taking care of the HC problem.

JellyBeanDriver
What do you mean they work over a narrow range? I ask because my wore out old motor was putting out 1300+ HC and the new cat brought it down to 13.

If you don't think a cat contributes to taking care of HC what do you think it does?

[INSIDIOUS '86]

Does the engine have an air pump? The air injected neer the exhaust valves helps treat hydrocarbons. This will help but can be done without.

What kind of carb do you have. It's possible that you have a leaky quadrajet this can make it run rich and throw the emmissions way off! There are pressed in plugs underneath that commonly leak.

Accelerator pump tunning can also help.

You can see rather quickly that a engine that doesn't have all equipment at 100% can start working against itself
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[JellyBeanDriver]

Originally Posted by LynnJr

If you don't think a cat contributes to taking care of HC what do you think it does?

You read my post wrong. I believe in HIS case it is not contributing to lowering the HC's because his motor is so far out of the operating conditions the cat needs to work properly.

[Desert1957]

If I read earlier in this thread, You DON't know where the timing is? High ignition timing can cause high HC readings, Use a timing light and set it to specs(lower the better) 4-6 max.

Another thing I have done with success is pull the PCV valve out of the valve cover and let it breath clean air. Any 160,000 mile small block is going to have a ton of "Blow BY" causing high HC readings.

Desert

[xrcr]

Have Historic tags on the 76 here in MO. No inspections required. It's not a DD but I drove it like one for years. They have to really want you, to mess with you on the mileage restriction

[LynnJr]

JellyBeanDriver
Got ya.
I wasn't trying to bust anyones chops as all these posts are valid.
Out here we have inspections every two years since 1975 and any vehicle with any miles on it is a tough pass.My buddy does the smog only tests at his shop meaning he is not allowed to touch the vehicles motor.He only tests them and can't add any parts even if you ask.
On several of my vehicles I spent well over $1000 a piece to get this or that fixed only to end up replacing the cat with a brand new one.I have never seen or heard of any vehicle with a BRAND NEW JUST INSTALLED cat failing and neither has he.
Air injection pumps simply add air so the exhaust can better burn anything left over the same as adding oxygen to a cutting torch allows it to get super hot and melt the metal.
A cat works the same way as it burns off everything not originally burned in the combustion chamber.It gets very hot and the passing exhaust gases get a second cooking if you will.
In a tired motor the cat is constantly cooking off and they will burn out very quickly.If you pull a cat off a passing vehicle and switch it to a failing vehicle chances are it won't work.You need a brand new cat installed and after it passes take it off or two months later it will no longer pass.
Out here I sawz-All my cat off as soon as I get home so its still good in 2 years.
The problem in my opinion is the OP's motor is a little long in the tooth and anything done to it won't last including putting on a new cat.My suggestion to add a brand new and not a new to this vehicle cat has never failed to work since 1975 out here on many many vehicles.
Out here your timing is checked by the computer on the diagnostic machine and is part of your print-out.If the timing is/was bad he should have that as a fail on his printout as your only allowed to be off 2 degrees.
I would wager a guess that the new cat was new to the vehicle but not new out of the box or that to much time passed between installing it and getting it checked.I am an old poster not a teenager and I've done all the tricks in the past.

[Jackie Mac]

UPDATE I passed emissions with a 7 on hydrocarbons( Down from the last 810) ended up finding a mechanic that does a lot of work on old trucks. The carb was way out of adjustment. It only took the guy about 30 minutes and the hydrocarbons dropped that much. I was amazed because the truck ran ok. He also adjusted the timing ahead to 4, but he said he has got a lot of these old trucks to pass and its almost always the carbs. Thanks for all the info from everyone. I hope this thread helps someone else with emissions. Joe

[JellyBeanDriver]

Originally Posted by Jackie Mac

UPDATE I passed emissions with a 7 on hydrocarbons( Down from the last 810) ended up finding a mechanic that does a lot of work on old trucks. The carb was way out of adjustment. It only took the guy about 30 minutes and the hydrocarbons dropped that much. I was amazed because the truck ran ok. He also adjusted the timing ahead to 4, but he said he has got a lot of these old trucks to pass and its almost always the carbs. Thanks for all the info from everyone. I hope this thread helps someone else with emissions. Joe

Yay! Congrats! Your engine will be happier too (as will your fuel bill).

[killthewabbit]

Double post?

[killthewabbit]

Triple post? WTF?

[killthewabbit]

Good job on the pass. I might need to get your hookup on the carb adjustment. Hard to find guys these days that know how to tune one. First year I had mine it got passed without even having a cat converter. I didn't even realize it was missing until the second time I went through MARTA and got nailed on the visual inspection.

Originally Posted by xrcr

Have Historic tags on the 76 here in MO. No inspections required. It's not a DD but I drove it like one for years. They have to really want you, to mess with you on the mileage restriction

So, your suggestion was for him to move to Missouri?

[motornut]

cool,yup that tuneup bill will pay for itself in fuel savings!

[Skunksmash]

Cheat.

[dieseldawg142]

^^^, yup, whatever is necessary! do our elected officials think air pollution will stop at our borders just because we have emission testing? unless the WHOLE world is in on it, it's kinda useless. it's just easier to pick on private vehicles then the real polluters (big trucks & industry)

[LynnJr]

A new cat did nothing and adjusting the idle screws brought it down 800 on the HC.I'd buy that guy a case of beer.

[muddnutz]

25 years or older doesnt need emmisions testing in Ga either most counties dont have any testing what so ever only in the metro atlanta area

[motornut]

Originally Posted by LynnJr

A new cat did nothing and adjusting the idle screws brought it down 800 on the HC.I'd buy that guy a case of beer.

good idea,and keep his phone number lol