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I did a tune-up and it failed the emissions test due to hi HC at idle. I'm thinking its vacuum leak because the idle is rough and it surges at a stop.
If you can help I would would be saved. I have to pass emissions ASAP.
Its on the RV I bought off here and its turning out well except the BS government hoops I have to jump through.
Did you change air filter, oil, oil filter and fresh gas before the test?
Yup, total tune-up. Plugs, wires, cap and rotor, air filter, oil and filter, gas treatment. And a fresh tank of gas. Adjusted the air fuel mixture screws down from 5 turns to 1.5 turns. Ran it for about 50 miles or so. Still failed the tailpipe test. I think its the vacuum lines that were screwed up.Quote:
Originally Posted by Ah Pook
Wish I could help.The oldest manuals we have back at the shop are late 80's
1977 460 vacumm diagram
https://images.search.yahoo.com/search/images;_ylt=A0SO8z31K4BTRAEA6w9XNyoA;_ylu=X3oDMTB0 bTh1YXVpBHNlYwNzYwRjb2xvA2dxMQR2dGlkA1ZJUDA0OF8x?_ adv_prop=image&fr=yfp-t-901&va=1977+460+vacuum+diagram
Did you change the PCV valve, air canister filter, and spray clean the egr valve? Is the EGR valve working? If you think it's a vacuum leak, whats the (IIRC 21") gauge telling you at idle? If it's a vacuum leak replace the vacuum lines. From the looks of it the ford has a sealed canister unlike a GM. So i'd splice the lines together by passing the canister.
That is something I havent tried yet.
Sometimes you can find where the leak is by spraying starting fluid or carb cleaner around suspected areas and listening for changes in idle. Something that old, if the vacuum lines felt dried out/brittle and I had the time and money, I would just buy a roll of new line and some assorted connectors/t's and set aside some time to go section by section and replace it all - but that might not even be your problem.
use something other than starting fluid. it's too light and has a tendency to be picked up by the intake and evaporates too fast. . As much as i despise WD40, it or something similar (oil based) works better since it doesn't burn off quick .Quote:
Originally Posted by GunsRBadMMMMKay
Surging at idle is almost definitely a vacuum leak.....on something that old I would use that diagram kazoo posted and just replace all the hoses vs trying to find the leak....vacuum hose is cheap
Anybody ever try a mixture of E-85 and gas at a 1:2 or 33% ratio to get these older (pre-80's) non-fuel injection engines to pass.
It used to be a fairly common practice to add high test alcohol to get vehicles to pass.
The lines will have issue with e-85. replacing the vac lines, checking the EGR valve and replacing the PCV valve should do it. The sympton showing is conducive with vac lines AND the often overlooked, EGR. Hooking a vac tester to the EGR will tell you if it is opening or not. Usually a removal (after soaking the bolts) in a good rust penetrater like CRC, etc makes it much easier. The guts of the valve clog up with carbon.Quote:
Originally Posted by Colorado Osprey
TWO other items often overlooked, the valve cover breather should be replaced AND one that fails a lot of vehicles, The Gas Cap.
I did something similar to get my 66' buick to pass. Damn near empty on gas, pour some 100% rubbing alcohol in the tank. BG 44k works wonders as well. And as a die hard bow tie man i must say......Quote:
Originally Posted by Colorado Osprey
Attachment 45207
Stop trying to pass, it's a waste of money... Co law says even if a car fails, if the owner can prove to the DMV you put "x%" money into the car trying to fix the problem they are require to still give you tags.
or you can drive to a small shop and pay the guy $65( I heard they are all over town and off federal)
Yep, tried it in my 1978 ford and it still failed. I used 80% e85 and 20% 91. It was an improvement but if an engine has a bad vacuum leak it won't help.Quote:
Originally Posted by Colorado Osprey
One thing i forgot regarding the 77 fords. IIRC 75-79? had issues with rough idle. There were a few fixes, temporary, it's one of those things. However making sure there are no vacuum leaks is one less thing contributing to overall performance and possible a lean burn / valve issue down the road.Quote:
Originally Posted by RonMexico
I had trouble once with the idle and carb on an old rv, it was related to vacuum lines but ended up being an issue with the vacuum advance and distributor timing (iirc someone had taken the check valve off one side and used it for a connector inline somewhere it wasn't supposed to be lol). IDK how that issue would affect emissions, there wasn't an etest there - but high hc would be running rich/unburnt fuel so could be a timing and/or carburetor issue too. Timing chains can stretch over time too, but that is more erratic in symptoms I think.
RonMexico is right, you get a waiver after so much money spent unless they changed it. I thought recreational and classic vehicles were exempt but just looked and apparently they changed that too? I hate emission test requirements.......
Ethanol in our fuel these days can do a number to the rubber in old carbs.
possibly rejet/adjust mixture (we are at altitude)
put a timing light on it
you dont know what the previous yahoo did under there unless you check.
I checked the EGR and made sure it was moving properly. I don't know if the vacuum was getting to it since it seemed that it wasn't. There was a few old lines that were just breaking apart when I moved them but I replaced those lines with new ones. I followed the diagrams as best I could to figure what went where. But I finally found the VECI sticker and looked at the gap setting. .42 - .46 is what it said and I set them all to .35. Do you think that could be the problem right there? I should regap them any way just because it calls for it but its a true PITA to get to the front 2 on both sides.
I sprayed some starting fluid on the choke and it seems to be leaking too. Most of the hoses have stopped though.
And I set the idle to 1000 rpm so it drops down to 800 when in gear. Do you know if that will be to high for the tester?
Thanks for all your help thus far. I think that old carb maybe the problem. The previous guy had a different one on there and switched it out before he sold. There is a hot wire that you stick on electric chokes still installed.
I can't do anything now since its raining. And maybe a tornado somewhere west of here.
ETA: I checked the timing too. With the vacuum off the distributor and all the other vacuum lines fixed as best I could tell I set the timing to 12 BTDC.
What sportbike said. 77 was a long time ago. Lots of chances for brother in laws and uncles to diddle with it. HC iis almost always an incomplete burn(miss). Are you sure the choke isn't sticking? A bottle of alcohol can help. if you can get it to smooth out it will likely pass. Truck emissions for that year are almost non-existant, if you can't get it to pass I'm telling Al Gore.
Using starting fluid on the carb was a mistake. You're getting a false response based on the SF / carb intake, USE PB blaster, or something similar. You need something that will adhere to the area in question, Not flash off fast. Not to say there isn't a base plate issue. However don't use s/fluid OR carb cleaner.Quote:
Originally Posted by DOC
I'd set them to spec, if your spark is to quick/short it can have trouble evenly igniting all the fuel in time for the cycle.Quote:
Originally Posted by DOC
As gunsRbad said, You're not creating enough spark @ 35 to ignite fuel / air mix. Not only are you not having proper ignition of fuel. Any unburnt fuel not fouling up the plugs, exhaust valves, is mixing with the oil. Incorrect gap can and will cause a series of other issues if not taken care of.
A few thou off the spark gap is not a issue. But it does beg the question of weather the ignition is up to the task. Get a spark checker. A timing light is your friend too. you may have a worn timing chain causing erratic timing, That was built in the age of nylon timing gears.
.10 difference will cause an issue. Consider the normal plug gap now shortened .10 unless he's inspected them since the initial install, i would say there's potential some of the ground electrodes have been pitted / compromised. If it was a tune up - emissions test, probably not. A Full tune up should include checking the timing. BUT some folks skip or overlook it. It's electronic ignition what could go wrong .Quote:
Originally Posted by ben4372
Timing chain is easy to check.