Emissions Problems

[kdubaz]

Ok, let me regale you all with my saga and the Arizona MVD.

Got a truck - '81 Chevy shortbed in pretty fair shape, with a pre-78 305/350 transplanted by someone else. I took the truck through emissions, stock, and failed miserably.

Next test was oil change, plugs, filter changes, etc, did better, still failed. 150 on the hydrocarbons - too much gas.

Took it to a muffler shop, installed a new catalytic converter, blew high again and failed.

Took the 2 barrel rochester carb off, had it rebuilt, then took it through again. Much better, but still failing - 55 out of 40 on HC.

Had it tweaked by a shop, blew 66 out of 40.

Had it rejetted, dropped it off at same shop, had it reinstalled. Went to drive it to emissions, it started dumping too much gas, had to get it towed home.

At this point, I was pretty sick of the whole carb situation, and I had a Edelbrock 600 at the house, so I figured I'd start fresh as it were. Eventually, this truck is going to be a show winner, and I'd like to keep the same motor since at one point it was running pretty well. Even if I upgraded to a 350, I'd still have the manifold and carb and I'd be ok, so I figured it wasn't a bad idea. Besides that, the carb was the problem on so many occasions, and I just didn't need to deal with it anymore.

FYI - I didn't hook up the choke cable, I just let it happen. That was probably a mistake.

Went through emissions, blew 176 out of 40 hc.

At this point, I was told by mechanics at my work and by friends that a 500 might be a better option. I went down to Lopers - a local performance shop - and they sold me another 600, but this one had a hookup for the charcoal canister and an electric choke. The theory was that the gas fumes weren't recirculating, so adding that port would help me out a lot. There were no 500 cfm Edelbrocks - or any other brand - that they had that would have the port for the canister. Plus this 600 was supposed to be tuned for emissions out of the box, and if I hooked everything up I'd be fine.

I hooked it all up, now it's idling at 2500 rpm, and I can't figure out why. Yes, I adjusted the idle. In fact it's all the way out and it STILL idles that high. I know it's dumping fuel like crazy because I can smell it, and I'm frustrated to all hell. I need this thing for work tomorrow, and I don't know how it's going to happen.

So.

Any suggestions on the immediate problem and more overall problems? I'm down with trying the alcohol trick, but I need to have an idea of how much. I'm down to do whatever at this point, I just need a friggin plate.

[blink32]

Originally Posted by kdubaz

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Any suggestions on the immediate problem and more overall problems?

Having been down this same path (in regards to the high idle) it sounds like a Vaccuum leak to me. You didn't mention the brand or if its a reman of the new 600 your using but I know from my research that the Rochester/Edelbrocks have issues with warping @ the air horn and flanges when tightened too much. Thats what mine suffered from. If its a rebuild I don't believe the major rebuild operations would even bother to check the plane on the mating surfaces, probably just slap in new gaskets. It could also be something internally incorrect. Have you checked your timing and made sure that was correct/close yet also?

You used to have a bagged focus wagon a couple of years back didn't you?

[84 400]

Wow this is strang. check the vacume lines and the timing. also being a 78 it would not have a egr vlve right? This is strange i would of thought the new carb would fix it too unless it is a reman