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Emissions SUCKS !!! (updated)

Well, here's the deal, it has literally been so long since i have messed with a carb'd motor,,,,maybe i am forgetting something,,,

Just got in from messin with this thing again, here's what i did...

retarded the timing back down, but the further i went, the more vacuum i lost, by the time i got it back down to stock area of timing,about 8 degrees (no vacuum advance) the vacuum gauge was reading like 10in/hg, tried adjusting the carb alittle here and there, pulled off a vacuum cap to create a vacuum leak,,,nothing really did anything significant.

so, now, the best vacuum i can get out of this,,,if i am reading this correctly is nearly 20 degrees advanced (no vacuum advance hooked up) and with a fulltime vac port unplugged,,got it at about 17in/hg.

i plugged the vacuum leak/port and the vac dropped to 10in/hg again...

the whole time, the vacuum gauge does not bounce more than MAYBE 1in/hg,,IF that,

it will run smooth, nice throttle response for the settings, but still smells abit rich from the pipes. ON EITHER WAY.

maybe i should just convert to TBI or something:p:

I am extremely frustrated, but suprisingly not pissed, maybe just not the right setup for this application or something,,,MAYBE i do need the A.I.R. injection on this thing..


ONE OTHER THING,,how far back from the header collectors is usually optimal for the proper heating of the cats? Mine are approximately 3.5, MAYBE 4feet back from the collector :eek1: (i didn't do this):crazy:

and again, i thank you all for any tips/tricks/advice on this thing:D
 
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Could be a mismatched timing cover/balancer giving you an inaccurate timing reading.

I'd reset timing to best vac (then back off a hair) and see if you get any pinging or hard cranking. if you don't then the timing is correct regardless of what the marks say. I'd also consider a new carb.

Rene
 
When you unpluged the vacum cap did the idle speed increase? If so, it's a sure indicator that your idle mixture is rich.

Kelvin
 
" i plugged the vacuum leak/port and the vac dropped to 10in/hg again..."
Now that just aint right, there HAS to be a problem if you plug a leak and your vacuum goes DOWN. It would have to be running so rich that it bogs down when you plug the leak, but you said its running good?
How did you adjust the idle mixture screws? Lean drop method, or just ballpark it out a couple turns?
 
I'm looking at yout last picture; the one under the truck showing the cat.

I could be way off here, but I think the cat looks too far back from the engine - this would cause the cat to not get hot enough... maybe not even "light off" at all. If you'd like, I'll measure as best I can off my '87 K5's TBI305 exhaust (single cat). I figure I'll measure from the bellhousing-to-block interface, to the cat, to eliminate the variables between our drivetrains.
 
88-383 said:
When you unpluged the vacum cap did the idle speed increase? If so, it's a sure indicator that your idle mixture is rich.

Kelvin
Click to expand...

yes, the idle speed increases, and the vacuum gauge goes up about 4-5 in/hg.

I have the timing set at about 6 degrees (base) hooked to a throttle controlled vacuum port (only vacuum when throttle is applied) a vacuum port opened up (uncapped ) about half way up the carb. It has about 16 in/hg of vacuum.
Adjusted the idle mixture screws to where the vacuum is at a happy medium, meaning turn slightly one way, the vacuum drops, turn the other way, the vacuum drops, it starts and runs fine, doesn't smell AS rich, but still doesn't smell like it will pass,,could be wrong though, but not likely:crazy: ,being that i have no way of testing it without the emissions equipment, i won't know until then.
 
jarheadk5 said:
I'm looking at yout last picture; the one under the truck showing the cat.

I could be way off here, but I think the cat looks too far back from the engine - this would cause the cat to not get hot enough... maybe not even "light off" at all. If you'd like, I'll measure as best I can off my '87 K5's TBI305 exhaust (single cat). I figure I'll measure from the bellhousing-to-block interface, to the cat, to eliminate the variables between our drivetrains.
Click to expand...

this is something i was wondering about too, as mentioned, it is a true dual, and both cats are about that far back, i am wondering if this isn't helping at all with the higher emissions,,
 
Ain't my fault my old carbed chit passes every two years . I even let it go without adjustment this year , failed , and got it to pass with the APT turndown , all with my own hands :thumb:
 
hope you get it smogged, i would hate to dump money into a rig that cant get registration to drive on the street. smog= spending money on garbage!!!!!
 
pauly383k10 said:
Ain't my fault my old carbed chit passes every two years . I even let it go without adjustment this year , failed , and got it to pass with the APT turndown , all with my own hands :thumb:
Click to expand...

andTEN tries later, i am only workin on my 3rd now, i'll get it, either way, even if i DO have to convert to TBi, which i would like anyways :p:
 
Your not going to afford fuel injection right now anyways . You need to lower the off idle gas flow , and move your cats closer .

And it was 3 tries . Each time just lowering my APT until I passed . It was a bolted on carb after my last emissions test anyway . I had never adjusted it internally until the next test .
 
4xcrazy said:
this is something i was wondering about too, as mentioned, it is a true dual, and both cats are about that far back, i am wondering if this isn't helping at all with the higher emissions,,
Click to expand...

This is one reason why it's federally illegal to change the number of cats the vehicle has, plus or minus, from stock.

In any case, I'd agree, those are probably too far back. Been awhile since I had a truck with a cat on it, but from your picture, I believe the heat shield just forward of the crossmember is where the stock cat was located.

As mentioned, they need to get up to "operating temp" to work correctly, and yours may not be.
 
I failed emmissions.... the guy tested it 3 times at the tester... as you get 3 tries.... I also failed for loose front ubolts (just put the truck on the road) and a loose pitman arm nut (2wd shaft for xover... seems the nut was stripped out.. so I used a front d60 pinion nut.. double the thickness thus more threads to grab.... CRANKED THAT SUCKER DOWN)

went to autozone... bought Guaranteed to Pass... followed instructions.. think it is fill tank, pour in, drive for 3/4 tank.... go take test.... passed first shot.....


so I am due for inspection this december... im not even gonna mess... $6 for that bottle... will use it everytime.... :bow:


*****
Edited:
Oh yeah... also when I passed.. later I realized the floats on my holley were too high and it was literally dumping fuel down the intake..... so I may have had passed if I noticed that but that bottle did something to even make that rich running sum biatch pass!!!!:haha:
 
As much as people hate emissions, it's rather obvious that many of the failures are exactly why emissions testing is in place.

I don't agree with anything more than the sniffer tests (visuals do nothing) though, don't get me wrong. :)
 
When using a vacuum gauge to adjust timing, you need to make sure the gauge is connected to a "Manifold" vacuum source, and not a "Port" vacuum source for this to work correctly. Any vacuum connection in the intake manifold or in the base plate of the carburetor is a "manifold" vacuum source. When you adjust your timing, leave the vacuum advance connnected. Then advance the timing until you reach maximum vacuum, then back off 1/2 to 1 inch (a hair) of vacuum. This will be the most efficient timing. If you had a stock GM camshaft you could time it with a timing light, but with an aftermarket camshaft that is not degreed in with a degree wheel, you have to use the vacuum gauge method to set the timing.
 
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