need advice on emissions test

Posted By: apairof66s

need advice on emissions test - 12/05/08 02:37 PM

I recently got my 68 Coronet running and now I need to pass emissions here in Arizona.
The motor is a 318,(probably original) with X heads,Offy dual plane intake,Edelbrock 1406 carb,and headers.
The vaccum advance is disconnected at the distributor and all vaccum ports on the carb are plugged.
Except for the new carb this is the setup that the car had when I bought it.
It has a automatic trans.
What I don't know is if the motor has 68 stock internals, ie; pistons, cam etc.
In this county you must pass emissions to register the car.
Any advice would be greatly appreciated........

Posted By: GoodysGotaCuda

Re: need advice on emissions test - 12/05/08 02:41 PM

If I remember in Vegas was the max idle rpm was 1,200. It'd be best to try and idle it up as close as you can to help clean it up. Also leaning out the mixture some as well. Is it just a sniffer? dyno?

Posted By: Rug_Trucker

Re: need advice on emissions test - 12/05/08 03:25 PM

Smogging a '68 is asinine!

Let's spend that money on illegal immigration.

Posted By: apairof66s

Re: need advice on emissions test - 12/05/08 03:26 PM

Thanks for the reply.
They use the probes in the tail pipe and run it on the dyno.
How should i lean out the mixture?

Posted By: GoodysGotaCuda

Re: need advice on emissions test - 12/05/08 03:34 PM

Quote:

Thanks for the reply.
They use the probes in the tail pipe and run it on the dyno.
How should i lean out the mixture?

Do you suspect the cam is still stock? How wild is it? That's the biggest cause of higher emissions. If it is fairly mild, you may be suprised to pass the test since you only have to pass '68 standards (I'd imagine). My stock 318 passed with no problems in nevada. After I swapped the cam, intake and headers, I couldn't pass it.

You would lean out the mixture on the edelbrock carb by turning the idle mixture screws clockwise, as well as changing the metering rods to a thicker rod.

My best suggestion is to hook the vacuum advance back up, and running it on the test. Get a copy of the readings IF you don't pass..and we can look at those and see what the engine is doing. (too rich, lean, etc).

Posted By: Pacnorthcuda

Re: need advice on emissions test - 12/05/08 03:53 PM

1)Pray you have something close to a stock cam.
2)As Goody stated, raise your idle to something in the 1000-1100 range (you may want to check on max allowable first, I think states vary)
3) Retard your timing! You want something in the 2-6 BTDC at idle--this can help big time
4) Lean the carb a bit but be careful--too much and you'll increase CO emmisions
5) Clean air filter--or NO air filter
6) Fresh oil change (it helps a bit)
7) An alcohol fuel mixture (at least 10%, you can increase it with gas line antifreeze in a nearly empty tank)
8) Make sure engine is warm, coolant temp should be at least 190

I agree smogging a 68 is insane

Posted By: apairof66s

Re: need advice on emissions test - 12/05/08 03:59 PM

Here's the max allowable hydrocarbons (hc) in ppm : 260 (loaded)
Carbon monoxide (co) in % : 3.89

Posted By: apairof66s

Re: need advice on emissions test - 12/05/08 04:26 PM

When I retard the timing a couple of degrees the idle drops (as to be expected).
The vaccum reads 10 in. hc.
the more retarded the timing the less vaccum, correct ????

Posted By: Pacnorthcuda

Re: need advice on emissions test - 12/05/08 04:50 PM

Quote:

When I retard the timing a couple of degrees the idle drops (as to be expected).
The vaccum reads 10 in. hc.
the more retarded the timing the less vaccum, correct ????

Yes you will have to increase your idle setting to compensate.
If your starting at 10 btdc I would probably drop it to 5.
Yes, less vacuum. How much vacuum do you have at 10btdc and 'normal' idle? Hopefully at least 15-16? Much less would indicate a higher duration than stock cam (in all probability, could be other things of course)

Posted By: Dakota_Don

Re: need advice on emissions test - 12/05/08 05:05 PM

run the tank down to about 1/4 and add 1 to 2 gal of methanol, if you add to much it run like crap, if that happens add about another gal of gas..

and it will pass the sniffer test.. then go fill the tank up asap.

Posted By: Neil

Re: need advice on emissions test - 12/05/08 05:07 PM

An msd box will help a buch with the lower rpm portion of the test if you have any sort of cam in it.

The air screws on the carburetor make a big difference. Finding the sweet spot can be tricky if you have an engine that is borderline on passing. You can always take it to a service station and have them set it up for you with their equipment and then take it back and get it tested.

If all else fails buy some catalytic convertors without the air tube and splice them in as far forward as you can.

Testing old cars is a money grab if you ask me. Sure they pollute more than new ones, but the amount of time they spend on the road is very small. Most people drive them a few times a month in the summer to go to car shows and thats about it.

Posted By: apairof66s

Re: need advice on emissions test - 12/05/08 05:09 PM

I checked the timing before changing anything and it read 16 to 17 degrees btdc. I retarded it to about 12 and turned up the idle a little. It seems to have a rougher idle at this point.
The vaccum is reading 9..........

Posted By: Neil

Re: need advice on emissions test - 12/05/08 05:17 PM

If you have not had it tested yet do that first, but get the engine tuned up and running smooth. Get some base numbers to start with first before you start chasing a problem that may or may not exist yet.

https://board.moparts.org/ubbthreads/show...e=1#Post4446839

Posted By: apairof66s

Re: need advice on emissions test - 12/05/08 05:20 PM

Thanks for all the replies.
I was hoping to pass on the first test !
Are my settings close enough to go try it ?

Posted By: Neil

Re: need advice on emissions test - 12/05/08 05:23 PM

I would set the timing to stock and make sure it has new plugs, plug wires, pvc, oil, air filter etc. and then test it.

Posted By: apairof66s

Re: need advice on emissions test - 12/05/08 05:26 PM

Thanks.
I'll post the results later today........

Posted By: Prodart440

Re: need advice on emissions test - 12/05/08 06:45 PM

Put classic car insurance on it and you don't have to pass emissions anymore!!

Posted By: dmerc

Re: need advice on emissions test - 12/05/08 06:59 PM

I thought only cars after 74 had to be sniffed. That's the way it is in NM.

Posted By: Prodart440

Re: need advice on emissions test - 12/05/08 07:31 PM

In AZ it is 67 and newer unless it is on a classic car insurance and NOT a daily driver.

Posted By: Pacnorthcuda

Re: need advice on emissions test - 12/05/08 08:20 PM

Quote:

I checked the timing before changing anything and it read 16 to 17 degrees btdc. I retarded it to about 12 and turned up the idle a little. It seems to have a rougher idle at this point.
The vaccum is reading 9..........

Your vacuum is only 9" ???? At what RPM?

Thats really low for anything expecting to pass emissions. You might try setting the timing a little higher just to get some vacuum back. But again, What is the idle speed?

Posted By: apairof66s

Re: need advice on emissions test - 12/06/08 05:57 AM

Quote:

Thanks.
I'll post the results later today........

They turned me away because I don't have tail pipes.
Over the weekend I'm going to fix that.......

Posted By: apairof66s

Re: need advice on emissions test - 12/06/08 06:08 AM

Quote:

Quote:

I checked the timing before changing anything and it read 16 to 17 degrees btdc. I retarded it to about 12 and turned up the idle a little. It seems to have a rougher idle at this point.
The vaccum is reading 9..........

Your vacuum is only 9" ???? At what RPM?

Thats really low for anything expecting to pass emissions. You might try setting the timing a little higher just to get some vacuum back. But again, What is the idle speed?

I don't have a tach on this car (maybe xmas !)
It feels like 950 to 1100 rpm with the timing at 12 degrees and 9 in. of vaccum.
A long time ago I was told to set the timing to maximum vaccum and then put the timing light on it for reference. That may not be the trick for passing emissions though.
I'll find out if the vaccum will increase above 10.
I'll post more results over the weekend.