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Anonymous
Guest
how big of a cam can I put in my 76 250 and still pas smog ?
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Anonymous
Guest
as big as you want if you move to Florida.....
what are the smog restirctions where you live? hey, would a cam affect smog in the first place?
what are the smog restirctions where you live? hey, would a cam affect smog in the first place?
It will depend on the rules in your area. Do you have to pass a sniffer, just a visual, a dyno, or what?
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Anonymous
Guest
the visual and sniffer
They still inspect a 76? That's 28 years old! Most states have a 25 year limit on emissions testing, figuring that the handful of cars that old are collector pieces not daily drivers.
66Monterey
Well-known member
NC currently has plug-in OBD II testing for '96+ cars,
tailpipe and visual testing for '75-'95,
visual + parts must work for '73-'74 (but no sniffer),
visual only for '68-'72.
And this is only for certain counties. Most get only safety inspections.
Confusing? NC DMV thought so, too...here's the new plan:
All counties will have plug-in OBD II testing and safety testing, but tailpipe testing will be discontinued.
tailpipe and visual testing for '75-'95,
visual + parts must work for '73-'74 (but no sniffer),
visual only for '68-'72.
And this is only for certain counties. Most get only safety inspections.
Confusing? NC DMV thought so, too...here's the new plan:
All counties will have plug-in OBD II testing and safety testing, but tailpipe testing will be discontinued.
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Anonymous
Guest
it isn`t just idle they make you run it up to 2500 rpm for a cuple of min. 
To the letter of the Clean Air Act of the late 60's, unless it has CARB or EO status, your dead. Down with legalistic hammer, and take the man out to the stocks for stoning. Thank goodness most states have there own ideas!
Cam
The general concensous (sp) is 270 degrees and about 0.26 * the maximum valve size in lift.Thats about 455 thou at the valve for a 1.75 intake. The critical part is the amount of degrees both valves are 30 thou open at the same time. This allows for quite savage opening rates that the get blunted off as the cam rises. Quite often , the 50 thou duration figures aren't very big on these cams.
Any standard 270 or so grind will most likely be set up with autos in mind, and these cams are good for emissions engines.
The plus is these cams make excellent torque, and thats what rules n the streets.
Work has been done with custom billets on differnt lobe centres for emmisions engines.
Visual and Sniffer Tests-what Iv've read
We all know the smog dawgs can bite hard if your 25 year old EGR, air-pump or PCV or thermostatic air valve isn't there, but these items really do improve cold starting. Most pollution is on start-up, and after that its just a matter of engine tunning. Many drivablity problems happen when items placed on the car as a development requirement from engineers in testing labs at Ford get thrown away, or loose servicablity. Often, a spike of alcohol or retarding the cam or ignition will help give you room if this is the case, but the real issue is its often impossible to get the exact replacement parts.
The advances over the last 25 years have been in cold start warming of the engine, and in using better fuel systems. These don't need as much heat as the 144-250 engines put into the intake manifold. I think Mark P related that the heat stove is a power waster after warm up, but that the EGR is not a problem. Fuel has gotten lighter since the heavy metal days of hi-test Sunoco or even the old regular gas.The oxygenates, extra alcohol and aromatics cause hot fuel handling problems these days with it.
They do, however, further lean-out the mixture. So the idle Co and Nox and HC standards in 1976 should be easily met.
There is lots of freedom to raise the compression by decking the block, using later larger chamber heads with HSC Tempo pistons, and using the Clifford port divider. The chamber and Fords gaskets were most likely designed around a blueprinted engine, but Ford had crazy wide production tollerances with respect to pistons, rods and deck height. All this doesn't change emissions if you are moderate in your mods. The exhast could be changed for a later type too, as long as the visual inspection is covered off. I think a better emissions area 2-bbl Holley Weber may be used if it has been benchmarked with a known combo. As long as its all tamper-proof and jetted right.
According to a Hot Rod article way back in 88, as long as the visual and sniffer test comply, then its okay to bechmark a stock 1-bbl car with the modification as long as theres no difference in any tailpipe emissions. What the Smog Dawgs get snarky over is the attitude that she'll be right. If you have gone some way to getting parts that have smog certification on other cars, retro fitting can't be a bad thing. There's lots of Pintos, Fairmont 2.3's and Fox stangs and Capri 2.6/2.8's to snatch Holley Webers or Motorcraft emmissions era carbs off. The ignition set-ups are another area. The vaccum advance units are not always compatiable, but if you use later emmissions spec ignitions, then you must win browny points.
Cam
The general concensous (sp) is 270 degrees and about 0.26 * the maximum valve size in lift.Thats about 455 thou at the valve for a 1.75 intake. The critical part is the amount of degrees both valves are 30 thou open at the same time. This allows for quite savage opening rates that the get blunted off as the cam rises. Quite often , the 50 thou duration figures aren't very big on these cams.
Any standard 270 or so grind will most likely be set up with autos in mind, and these cams are good for emissions engines.
The plus is these cams make excellent torque, and thats what rules n the streets.
Work has been done with custom billets on differnt lobe centres for emmisions engines.
Visual and Sniffer Tests-what Iv've read
We all know the smog dawgs can bite hard if your 25 year old EGR, air-pump or PCV or thermostatic air valve isn't there, but these items really do improve cold starting. Most pollution is on start-up, and after that its just a matter of engine tunning. Many drivablity problems happen when items placed on the car as a development requirement from engineers in testing labs at Ford get thrown away, or loose servicablity. Often, a spike of alcohol or retarding the cam or ignition will help give you room if this is the case, but the real issue is its often impossible to get the exact replacement parts.
The advances over the last 25 years have been in cold start warming of the engine, and in using better fuel systems. These don't need as much heat as the 144-250 engines put into the intake manifold. I think Mark P related that the heat stove is a power waster after warm up, but that the EGR is not a problem. Fuel has gotten lighter since the heavy metal days of hi-test Sunoco or even the old regular gas.The oxygenates, extra alcohol and aromatics cause hot fuel handling problems these days with it.
They do, however, further lean-out the mixture. So the idle Co and Nox and HC standards in 1976 should be easily met.
There is lots of freedom to raise the compression by decking the block, using later larger chamber heads with HSC Tempo pistons, and using the Clifford port divider. The chamber and Fords gaskets were most likely designed around a blueprinted engine, but Ford had crazy wide production tollerances with respect to pistons, rods and deck height. All this doesn't change emissions if you are moderate in your mods. The exhast could be changed for a later type too, as long as the visual inspection is covered off. I think a better emissions area 2-bbl Holley Weber may be used if it has been benchmarked with a known combo. As long as its all tamper-proof and jetted right.
According to a Hot Rod article way back in 88, as long as the visual and sniffer test comply, then its okay to bechmark a stock 1-bbl car with the modification as long as theres no difference in any tailpipe emissions. What the Smog Dawgs get snarky over is the attitude that she'll be right. If you have gone some way to getting parts that have smog certification on other cars, retro fitting can't be a bad thing. There's lots of Pintos, Fairmont 2.3's and Fox stangs and Capri 2.6/2.8's to snatch Holley Webers or Motorcraft emmissions era carbs off. The ignition set-ups are another area. The vaccum advance units are not always compatiable, but if you use later emmissions spec ignitions, then you must win browny points.
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Anonymous
Guest
I do still have all the smog stuff the old egr valve kicked the bucket but I think I have a nother that will work if not then thats a nother $55.oo that bit me in the but :roll: .
I have a gole of about 270 hp at the wheels going through a T5 and 4.11:1 gears in a 8 inch . If I got a bigger cam than a 270 would I be able to retard it enuf to make it work ?
I have a gole of about 270 hp at the wheels going through a T5 and 4.11:1 gears in a 8 inch . If I got a bigger cam than a 270 would I be able to retard it enuf to make it work ?
At crane they had an emmisions dyno and they tested a lot of cams. sorry part was the only engines tested were sbc and sbf (5.0 efi)
But one would be surprized to see how much cam can be used and still pass a sniffer test. Regular catalog cams that got carb EO #s were as big as 216' intake and 228' on 112cl these used to be refered to as hmv-272
cams I think they might have a new name but I bet money profile is the same. Of course the smaller hmv-260 and hmv-248 got carbnumbers as well. up about 2500rpm a 260 cam might really help some with emmisions
as long as you don't turn up the ignition timing too much.
Jim
But one would be surprized to see how much cam can be used and still pass a sniffer test. Regular catalog cams that got carb EO #s were as big as 216' intake and 228' on 112cl these used to be refered to as hmv-272
cams I think they might have a new name but I bet money profile is the same. Of course the smaller hmv-260 and hmv-248 got carbnumbers as well. up about 2500rpm a 260 cam might really help some with emmisions
as long as you don't turn up the ignition timing too much.
Jim
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Anonymous
Guest
The hot-air stove is only used when the engine is cold or the outside air is very cold (like 10 degrees or less). It does lower the air density, but the warmer air keeps the carb throat from icing when accelerating. Normally, the vacuum piston in the air cleaner nozzle redirects to cold air after the engine warms up.
In stock trim, EGR will actually increase hydrocarbon emissions UNLESS the air pump (or air 'snorkle', as Ford calls it on the '70s models) is actually moving air into the exhaust manifold. Then it will lower the hydrocarbons in the catalytic converter, using the extra oxygen to burn them off. EGR 'interrupts' the burn cycle in the cylinder because it displaces the oxygen that would normally be there with burned exhaust gases. This leaves a little fuel left over, which them gets burned in the cat. This is why most engines lose HP with EGR systems.
The best way to get through tough emissions situations is:
1. Back off the timing a few degrees. This lowers hydrocarbons.
2. Turn the carb idle mix screw in until the engine is stumbling, then slowly back it out until the engine can just idle. This isn't optimum, but it's lean, so the CO emissions will be lower. Be sure to do this with a fully warmed-up engine.
3. Run at least a 180 thermostat. A 195 is even better. Hotter engines burn off more hydrocarbons and eat up the extra fuel, reducing the CO.
4. If you're rebuilding, keep the compression ratio below 9.1:1. Going higher can cause high hydrocarbons, and there is little you can do about it, short of reshaping the combustion chamber for better burn rates.
Hope this helps.
MarkP
In stock trim, EGR will actually increase hydrocarbon emissions UNLESS the air pump (or air 'snorkle', as Ford calls it on the '70s models) is actually moving air into the exhaust manifold. Then it will lower the hydrocarbons in the catalytic converter, using the extra oxygen to burn them off. EGR 'interrupts' the burn cycle in the cylinder because it displaces the oxygen that would normally be there with burned exhaust gases. This leaves a little fuel left over, which them gets burned in the cat. This is why most engines lose HP with EGR systems.
The best way to get through tough emissions situations is:
1. Back off the timing a few degrees. This lowers hydrocarbons.
2. Turn the carb idle mix screw in until the engine is stumbling, then slowly back it out until the engine can just idle. This isn't optimum, but it's lean, so the CO emissions will be lower. Be sure to do this with a fully warmed-up engine.
3. Run at least a 180 thermostat. A 195 is even better. Hotter engines burn off more hydrocarbons and eat up the extra fuel, reducing the CO.
4. If you're rebuilding, keep the compression ratio below 9.1:1. Going higher can cause high hydrocarbons, and there is little you can do about it, short of reshaping the combustion chamber for better burn rates.
Hope this helps.
MarkP
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Anonymous
Guest
I'm alittle suprised to see that your '76 has to run through hoops to pass the Missouri emissions test. When I took my '79 in all they did was a visual and idle test. No acceleration was done.
I wonder what the differences are between cars and trucks for the same decade? Hmmm
I wonder what the differences are between cars and trucks for the same decade? Hmmm
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