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My 85 S-10 LB PU w/2.8L is overdue for smog here in Ca. When I got it back from long term loan to my daughter, it "bucks" like a bronko in 1st 2nd and 3rd. Runs good while warming up with choke on. I'm looking for a used carb, but in the meantime I would like to troubleshoot to make sure it is not something else. Fuel pump, vac lines etc.
 

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Every 2.8L I have ever had (all 2 lol) has had intake mani leaks. I was told by a smog guy that the intake leaks are a common prob and since the runner seams are under the valve cover it is almost imposable to detect!! I would start with that, both of my trucks (one was carb the other was TBI) ran better after replacing the intake gskts.
 

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What's in a name?....
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I've replaced my intake gaskets twice so far, still hasn't helped that problem. Wouldn't be a bad idea to change those though.
The next thing I did was check my timing, as I found it to be quite a bit advanced. I retarded it and it reduced the bucking quite a bit, though still does it when I least expect it. Vacuum leak is what everyone has been telling me to check next. Eliminating the intake manifold (just because I can't bring myself to pull the SOB a third time), I figure I have vacuum hose routing problems. still don't know where it went wrong, but dB Zac is right about it being a vacuum leak. How's it idle?
 

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What's in a name?....
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Have you sprayed carb cleaner at the intake manifold to see if the idle changes to help identify a vacuum leak for sure?

I need to recheck my timing as well. I did a body lift on the truck and may have "adjusted" the distributor using the body as a tool:)

dB Zac, didn't know that about the cowl and distributor. Very good to know about! Thanks for posting that.
 

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Typo King
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free carb

I bought a 1984 s-10 with a 2.8 for parts (I needed a front end) so I have a carb that I will not use or need. Pay shipping you can have it, but I have to tell you I got the truck for 100 bucks becasue the motor was blown, so I don't know how well the carb worked.
 

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What would be the result of an intake manifold leaK. Would it cause a high idle (1500-2000 rpm) when the vehicle is warm only and not when it's cold - cause that's my :censor: problem
 
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