Failed emissions testing

[gws34]

So I finally got my 1975 bronco on the road with a 3 day permit to go get it tested for emissions and it has failed horribly!

The previous owner had removed all of the emissions equipment so I have spent over 2 years to replace all of these parts and rebuild this system.

Here is what has been replaced

New carb from local auto store 2150 to replace 2100 that was on it
New smog pump and valves
all new hoses for smog pump
all new or NOS ported vacuum switches and vacuum lines
New exhaust from behind manifolds including cat
New EGR
Nos Vacuum valves for Smog setup
Replaced distributor (was points) now duraspark 2 with new ignition module
and many more parts replaced, it has been a long time working on this

The test results were as follows
HC- loaded reading 222 - loaded standard 250 - PASSED
HC - idle reading 429 - idle standard 250 - FAILED
CO - loaded reading 6.47 - loaded standard 1.50 - FAILED
CO - idle reading 6.46 - idle standard 2.00 FAILED

I do know that my carb is running rich because the idle mixture screws are out more than the recommended 2 turns. The passenger side is actually a few turns further out than the drivers side on. I have them set to get a steady vacuum of 18 and the engine runs smooth. When I turn them in the engine runs horribly and the vacuum needle bounces way up and down.

I have also checked the cylinder compression and here is what I have. Not in cylinder number but in location

Drivers side from front to back 120,142,135,110
passengers side front to back 130,140,132,120

So I know compression is not great and there is more than a 10% variation in cylinders.

So thoughts on what I need to do next??
Rebuild the Carb?
Rebuild the cylinder heads?
Rebuild the engine?

I need to get this on the road soon or it is becoming a sore subject with the wife. it has been sitting in the garage and not on the road with lots of money spent on parts and emissions and to have it fail it just hurts that much more.

The solution for me is to do this legally and not register it as a collectors vehicle, this is going to be a daily driver and it has to pass AZ emissions to even be registered.

Any suggestions?

 

[SteveL]

If any years are exempt there I would get this one going and sell it to purchase an earlier year. Who wants to deal with this every 2 years or whatever az requires.

 

[Broncobowsher]

What's the timing set to?

 

[spap]

What state are you in? As or Ca
Doesn’t ca have a waiver if you have spent more than 600/700 dollars.
And aren’t 1975 cars exempt
Sorry to hear you are going through the hassle

 

[nvrstuk]

Sorry to hear about all the time & money spent and still not meeting emissions. Wish ya the best and all the experts here from these States should get your Bronco in the winners (emissions) circle. I'm not an emissions guy but timing, idle circuit, jets, and getting the engine and keeping it up to t-stat temp during the testing should help...

I can't imagine what my Bronco #'s would be... lol

 

[Ovalis]

Yes, need to check your timing and also need to see what jets are in the carb you got. Check your spark plugs and if they're black instead of grey then you're too rich with your jets. The jet issue won't really help you at idle, but it will on your loaded test.

 

[jamesroney]

His original post says Arizona.

 

[Broncobowsher]

High CO mean rich
High HC is a misfire, or extreme rich.

Looks like you are on the extreme rich.

The choke was open?

It is generally a lucky guess if you can set an old carbed engine to pass emissions by feel. I remember in the old days it was a double tune up. First one was to get it through emissions, second one was to make it driveable. Took an exhaust sniffer to get the first one.

It could be that you just got a junk carb.

 

[73azbronco]

https://www.carburetorsunlimited.com/Take it to this guy, he will get it fixed and running better then new. He is the guy who rebuilds quadrajets for the offroad racers, he knows his stuff.

He can probably get it to pass with minor adjustments, but might need to return to get it driveable again if you know what I mean.

 

[EPB72]

Yes its running rich since being a auto parts carb you don"t Know float level,jet size and boost venturi size all can effect loaded co reading..Leaning out carb could drop HC a bit but you say starts running rough at this point I'd think the HC will start climbing alot.
also when leaned out confirmed no vacuum leaks?

So when you lean out the idle mixture screws the vacuum gauge bounces rapid and quick bounces or slow up and down flucuations? If rapid possible valve,valve seat issues,,and since #8 is contributing some the overly rich mixture is helping it more....
A cylinder leak down test would be next step to help confirm if valve job or go futher..

And yes Base Timing ??and timing curve total timing since distributor was replaced ,more often then not there not set up right need to be checked

But compression 142 down to 110 red flag .and since this is a keeper for you WELL...

?? Do you have a Catalyst or non Catalyst...

 

[73azbronco]

Or buy a place in Payson, Gila county, no vehicle checks up here.

 

[gws34]

Thank you for all the responses so far..

SteveL- 69 and up has to pass emissions here and it is every year. Yes if I had known would not have purchased a 75, but trying to stick with it since I have it

Broncobowser- Timing is 6 degrees btdc

spap- I am in AZ, yes if you spend over 600 you can get a waiver for 1 year only and you are not allowed to get it again. But the 600 has to be after the test, I spent lots of money before the test


Ovalis- Spark plugs look good so far. I guess it is time to pull apart the carb, I guess that is what i get for buying an autoparts store carb.


EPB72- Yes I guess I have to pull apart the carb and see what I can figure out.

I will have to confirm what my total timing curve is- do not have that number right now

Do you have a catalyst?- yes I have a Catalytic converter on it.

Thank you all. Will start pulling apart carb and see what I can figure out

Since having problem with store purchased carb would it be avisable to stay away from auto store rebuilt cylinder heads? Thought that might be a quick turnaround to replace and see if that helps compared to the wait time for a shop to rebuild my heads now.

 

[gws34]

Where do you buy jets from? These are 52's in the bronco now, sounds like I should get down to a 48 or 46.

 

[Timmy390]

Where do you buy jets from? These are 52's in the bronco now, sounds like I should get down to a 48 or 46.

Not saying this is the best place but gives you a starting point
https://quadrajetparts.com/2100-2150-jets-c-410_413_429.html

Tim

 

[gws34]

can you get jets locally or are they only order from a carb place?

 

[Timmy390]

Last ones I bought (not for a ford) I got online. Got a kit with a full range of jets.

Tim

 

[Rustytruck]

Put in a 190 thermostat and use Chevron gas. Taking it to Corroborators unlimited would save you allot of time and hassles. you saved enough doing the work yourself unless you have an exhaust analyzer your just going to have to anti up. I would do a proper compression test and a leak-down test before you start spending money on engine jobs. Make sure your oil is not fuel contaminated. Swapping out a true Bronco carb is never a good deal. pull the top off the carb and check the jet sizes. what is the size of the carb you have. its stamped on the side of the carb looks like a clock with large center number like 1.8 is the choke setting and opening up properly? first thing in the morning push the gas peddle all the way to the floor and let off pull the air cleaner, is the choke butterfly almost completely closed? now start the truck and let it warm up then blip the gas peddle. the choke should be wide open.
next time you go into smog test make sure the engine is fully warmed up and hot do not shut off the engine once you get to the smog station. if Broncos are operating normally and set to factory specs they are not noted for being hard to pass their smog tests, the tolerances are not too narrow like new cars. once they are not stock they become much harder to pass.
detail pictures of your carb at all sides wouldn't hurt.

 

[Rustytruck]

here is some help.

https://www.therangerstation.com/tech_library/pdf_documents/motorcraft_2150_carb.pdf

 

[gws34]

Rustytruck-

It is a 1.8 The jets are 52 so i just ordered 46 and 48 size jets.

Unfortunatly the previous owner had put a 2100 carb on this and the stock should be a 2150 in the research I have found. So I was not able to spend the money and find a true motorcraft 2150 at that time. So i went with what I could get.

yes the butterfly does what it should I believe I have all of that set up correctly.
Yes the bronco was fully warmed up and was never shut off until the inspector shut it off after the test.

I am trying to get it back to "stock" but as I mentioned the previous owner ripped it all out and some of these parts are not manufactured any more. 1975 is the only year with and electrical connection on the PVS. Took my many months to figure this out as others bronco owners that have not had a 75 did not even know this. So it has been a long and slow discovery and I just tackle the next problem as I get to it. I will start with the Carb and see how I can get that to help and I will continue to play with timing.
Some people seem to think it is easy for a bronco to pass others have stories of going in 2- 3 times to get it done.

 

[Broncobowsher]

Don't worry about jets until the idle is taken care of. Fix the idle and it very likely will fix the cruise as well.