my carb is dead

[txchainsawgogi]

the truck is hard to start and when it does, it doesn't sound normal anymore...and if I take my foot off the gas it dies. A look under the hood shows that the carbs butterflies will only move by hand...and seem to have a flimsy movement...as if someone retarded rebuilt it and wasn't paying attention when putting it back together. Shouldn't one open when the throttle is engaged?


Keep in mind I haven't been driving this vehicle, last week it ran fine(the best it has) after changing the radiator, thermostat and plugs.  Plugs are gapped, boots are tight.


Edit* it magically started just fine, idled just fine and is currently running smoothly. All I did was switch air cleaners...makes zero sense. Carbs are def next to replace after distributor and wires.
Help!

78 C10 350ci

[Layne]

Sure you're not looking at the choke butterflys?

[eventhorizon66]

Don't replace it, rebuild it.  We are talking about a Q-jet, right?  Your choke probably needs adjustment, also check your choke pulloff.

http://forum.73-87chevytrucks.com/smforum/index.php?topic=17001.0

You as far as the butterfly not moving, you were probably playing with the air valve.  It is not supposed to move until the engine vacuum draws it open under high throttle/high load situations.

http://www.youtube.com/watch?v=nRK9n4NQvOA

[Layne]

That vid is awesome! QUIT THAT!

[txchainsawgogi]

Cool...I may need help rebuilding it. Is there a kit I should be looking for?

[eventhorizon66]

Here's a quality rebuilt kit: http://www.cliffshighperformance.com/carbkits.html

And here is an excellent reference: http://www.amazon.com/Rebuild-Modify-Rochester-Quadrajet-Carburetors/dp/1932494189/ref=sr_1_1?ie=UTF8&s=books&qid=1281933763&sr=8-1

[txchainsawgogi]

Oh...I guess my choke pull is loose, those are the parts that feel like they can't be on there right.

[txchainsawgogi]

This looks decent...for around the same price as a rebuild kit that is...

What's the round part under the choke?

http://cgi.ebay.com/ebaymotors/Rebuilt-Quadrajet-17059222-79-Chevy-305-350-Carburetor-_W0QQcmdZViewItemQQitemZ330460268835QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_566wt_941

[TexasRed]

You mean the choke pull off?

That's a hot air choke, do you have that or an electric choke?

[txchainsawgogi]

Well I guess mine is electric, because I don't have that hot air bit attached to mine... under the choke pull off there is nothing there.

[jaredts]

I want to say a standard quadrajet rebuild kit is like $30.  That Cliffs performance rebuild might be worth it but you can get by for much less.  Having said that, I'd be a rich man if I had a nickel for every time someone wrongly said their carb. was screwed up and that was the problem with their engine (me included).  Maybe its just me but I think your time would be best suited getting to know the adjustments on the carb. and everything related to actually troubleshoot the problem.  Buy a carb. off Ebay with no warranty and little knowledge of how to tune one once you install it and you'll likely be frustrated and worse off.  You need to go step by step through tuning the one you have before you even know that it isn't in top notch shape but in need of adjustment.

[eventhorizon66]

Maybe its just me but I think your time would be best suited getting to know the adjustments on the carb. and everything related to actually troubleshoot the problem.  Buy a carb. off Ebay with no warranty and little knowledge of how to tune one once you install it and you'll likely be frustrated and worse off.  You need to go step by step through tuning the one you have before you even know that it isn't in top notch shape but in need of adjustment.

Bingo!

But, if you continue to pursue a rebuild, stick with electric choke.  For $99, it's unlikely that is a satisfactory rebuild.  If you are looking for a quality rebuilt unit check out SMI, The Carb Shop, or Cliff's.  It's gonna cost you alot more the $99, though.

I want to say a standard quadrajet rebuild kit is like $30.  That Cliffs performance rebuild might be worth it but you can get by for much less.

I doubt a $30 rebuilt includes much more than gaskets and a needle/seat assembly.  I wouldn't waste my time on a half-effort rebuild.  That said, I'm sure there is a better "bang-for-the-buck" rebuild kit out there than the one I posted.

[txchainsawgogi]

I've dealt with holley carbs but its been awhile since I've messed with cars. I've been into motorcycles for the past 4 years. I've done rebuilds on those quite a bit.

I'm sure I can do a rebuild myself but I will for sure need help tuning it.   Though, couldn't I just buy new jets of the same type and get the carb clean and back to stock?

If I'm not changing yet (dual exhaust, intake manifold) would it even need to be tuned differently? I'm doing away with the emissions stuff, since half of its missing anyway.

[eventhorizon66]

That book I posted earlier contains all the info you need to properly rebuild and calibrate a q-jet.

[jaredts]

You can get that book or I found a step by step adjustment procedure on the web somewhere once.  I think my book is a Haynes book from an auto parts store.  The adjustments you need to check have nothing to do with jets either.  You just need to check the simple stuff like choke adjustment, idle stop screw, fast idle screw, verify choke pulloff operation, spring windup on the secondary airflaps, idle mixture adjustment screws.  While you're there check for vacuum leaks and check accelerator pump operation.  Since people tend to mess with the choke a lot, it is often the one you'll find all screwed up.  It might also be helpful to use a ton of carb. cleaner on every moving part before you start adjusting just to make sure nothing's gummed up and sticking.