the 75 f250 i just got from a friend has been giving him trouble passing emissions since he got it. i am now the owner and i am working on restoring it.
i have been arguing with my dad about wheather it should have a cat on it or not. was the 75 originaly equiped with one? the engine was rebuilt before he got it. can anyone give me any advise as to why its not passing? but my biggest question is if it was originaly equiped with a cat.

 

I have an early 77 model year built in 76. F250 400 auto. I passed rigid CA with no cat. The BAR in Sacramento faxed me a Mitchells book page to show no cat in that year with that engine. Mine is a CA model. Fact is, some had it some didn't. To find out why yours won't pass, give us more info. engine?, GVW? The page I have shows no cat for over 6,000 GVW in 1975. Check your ignition tune/timing. Check your egr valve (engine should stall at idle when egr solenoid vacuum is temp. connected to full manifold vac. If the problem is nox, like mine was, I installed a homemade water injector system to spray water mist directly in the throat of the carb, NOX can only form at high temps. Water injection also decarbonizes the intake manifold.

 

its got a 360 bored to 390.

 

The odds are very high that your truck did not have cats, or EGR or a smog pump. To settle the argument with your dad, show him your gas gauge. If it says 'unleaded fuel only' it had a cat. If it only says 'fuel' with no warning, it was cat free from the factory. Now, your dad's argument might not be that it had a cat factory, but that to pass smog now it needs one to clean up the tail pipe enough to pass. That may be the case.

What are your test numbers and the pass/fail criteria of your test? You state that the truck was rebuilt. If that's the case and the compression was bumped up or a hotter cam installed, your emissions could be greatly changed from stock.

Make sure the engine is in good tune, fresh plugs, timing, oil change. Some people run the tank down low and then dump a couple of bottles of dry-gas in the tank.

 

I see you're in AZ. Was your test done only at idle, or was a dynonometer used? As above, post the test results! Did you fail on visual inspection (missing parts) or high emissions; if so which emissions, HC, CO, NOX? Tested as a 360 or 390? Does AZ have a referee? See if someone at MVD can help you with options before spending any money on repairs. Installing a cat on a vehicle not designed for one would not be advised in CA due to fire hazard, causing engine damage and it not being legal (or necessary). Your vehicle needs only to test to the specs it was designed for when it left the factory. Your state should give you the specs that apply for your year and GVW rating. There may be a cap on the amount you're required to spend on repairs, or a program to help with the repairs if needed.

Here's what the book shows as required devices for 75 w/360ci. and things to check:
PVC-check hose routing, clean or replace pvc valve.
ACL-thermostatic controlled air cleaner. Is acl orig and in good shape? vacuum motor hooked up? Any vacuum leaks?
Evap- prevents vapor from tank and carb bowl from entering atmosphere. Tested by visual inspection only.
AIS- Your truck should have Fords Thermactor system (smog pump). Check pump output and air dump valve. This system injects fresh air, under certain operating conditions, in to the exhaust manifold or through channels in the intake manifold leading to the exhaust ports.

No EGR was used on the 75 360 if vehicle was over 6001 GVW.

 

not all 360's had air pumps in 75 f250 didnot have cats usually just pcv ,and egr and not all had egragain what part are you failing hc,co, nox

 

i dont know what was to high on the test as i am not the one who tested it and i dont have the print out sheet. i plan to take it and have it tested as soon as i get the power steering working again. it doesnt have an air pump and i didnt see and egr on it. i had already thought of cleaning that out if it had one but i didnt see it. my cousin knows quit abit oubout fords and he told me to buy this stuff at autozone made by crc "guarenteed to pass our double your money back" and to close the mixture jets all the way and then open them 2 1/2 turns. ill try that. hopefully i get this worked out soon. i cant wait to be able to drive it when i want. thanks for all the help and info

 

as far as i know it has the stock cam.