Quadrajunk blues...

[tex_waco_usmc]

OK, so I am working on trying to get a SB 305 running that has been set up for 2+ years. The history on the truck is simple. My fathers truck, turned my daughters truck after it sat at my house for 2+ years with my father saying I am going to fix it up... (We all know how that sometimes goes)... She ran good but was pumping fuel straight into the exhaust and backfiring and leaking out of the carb... 65 miles and I ran through 15 gallons of fuel (You do the math, LMAO) So, she got parked until we could get around to her. There she sat until my daughter decided she wanted the truck and dear old dad said "sure your dad can get that running good for you!" LMAO....

Went out yesterday and it has a Rochester sitting on top of it. When a little fuel was poured down the throat it leaked out on the passenger side front corner, I believe out of the vacuum port that is there. Wouldnt fire, but did choke a little bit. Slapped the Original Rochester back on her, that I could not remember what was wrong with it and poured a little fuel down her throat and fuel leaked out where the throttle linkage goes into the carb... LMAO, now I remember why we pulled it in the first place!

So I am going to attempt to rebuild one of these two carbs for this truck just to get her running! Im looking forward to it. Is there anything I should be worried about?

[geezer#99]

Not hard to do. Here's some links.
http://www.vetteprojects.com/kstyer/quadrajet.htm
http://www.digitalcorvettes.com/foru...ad.php?t=88376

[69gmcc10]

make sure you get the ethanol friendly accelerator pump!

I just bought my rebuild kit from cliffs high performance. told him what i was running and at what elevation i was at and he sent me the correct jest, rod, and needles. great service and advice!

[tex_waco_usmc]

Awesome! I actually found some really good videos on youtube that are literally step-by-step how to rebuild a quadrajet...

Anyone know what numbers I need to get off of these carbs to get a good rebuild kit and then where I might get the best deal on a rebuild kit?

[flyingtim01]

There are two things off the top of my head to think about when you're doing a Quadrajet. First is a lot of the throttle shafts are sloppy in the throttle plate. Wiggle the primary and secondary shafts and if you have any up and down play, you should re-bush the throttle plate. (Sounds like at least one of them is loose, if gas runs out around the throttle shaft when you pour fuel into the carb)

Also, when you take the carb apart, it's pretty good practice to epoxy the bottom of the plugs in the float bowl. They start to leak over the years, and if the truck sits for a day or two, you'll end up with a hard starting truck because all the fuel has leaked out of the float bowl.

Also make sure you use a brass float when it goes back together. The black nitrophyl floats tend to absorb fuel when they get older and get heavy. The brass stands up much better to the ethanol, as well.

Speaking of floats, make sure not to skip the float height step and assume it's good enough without measuring. I suspect your float height was off on the first carb, which is why it was dumping way more fuel than was needed into the bowl and leaking all over the place, and you were getting raw fuel out of the exhaust. I guess it could also have been adjusted way too rich, but I doubt it would have run very well like that.

Note how far out your mixture screws are before you remove them, just as an FYI kinda thing. Once you get it back together, set both screws to 2.5 turns out, that should get you close enough to get it to run, warm up and start dialing it in.

It's a good time to check your choke pull offs as well, and make sure they hold vacuum.

A lot of times the kit you get might have the wrong base gasket for your application, and you'll end up with a vacuum leak or the truck just won't run right. Some kits come with 2 or 3 though, so make sure you use the right one. Take care removing your original base gasket, you might have to re-use it.

They're not hard carbs to rebuild. Just take your time, take pictures if needed. Once you get it all back up and running, dial it in, and down the road you go.

[flyingtim01]

The carb number is stamped (not cast) into the side of the carb. It will either start with a '17' or if it's older, a '7'. If it's REALLY old, it may even be on a circular tag attached to the body of the carb.

[tex_waco_usmc]

Originally Posted by flyingtim01

There are two things off the top of my head to think about when you're doing a Quadrajet. First is a lot of the throttle shafts are sloppy in the throttle plate. Wiggle the primary and secondary shafts and if you have any up and down play, you should re-bush the throttle plate. (Sounds like at least one of them is loose, if gas runs out around the throttle shaft when you pour fuel into the carb)

Also, when you take the carb apart, it's pretty good practice to epoxy the bottom of the plugs in the float bowl. They start to leak over the years, and if the truck sits for a day or two, you'll end up with a hard starting truck because all the fuel has leaked out of the float bowl.

Also make sure you use a brass float when it goes back together. The black nitrophyl floats tend to absorb fuel when they get older and get heavy. The brass stands up much better to the ethanol, as well.

Speaking of floats, make sure not to skip the float height step and assume it's good enough without measuring. I suspect your float height was off on the first carb, which is why it was dumping way more fuel than was needed into the bowl and leaking all over the place, and you were getting raw fuel out of the exhaust. I guess it could also have been adjusted way too rich, but I doubt it would have run very well like that.

Note how far out your mixture screws are before you remove them, just as an FYI kinda thing. Once you get it back together, set both screws to 2.5 turns out, that should get you close enough to get it to run, warm up and start dialing it in.

It's a good time to check your choke pull offs as well, and make sure they hold vacuum.

A lot of times the kit you get might have the wrong base gasket for your application, and you'll end up with a vacuum leak or the truck just won't run right. Some kits come with 2 or 3 though, so make sure you use the right one. Take care removing your original base gasket, you might have to re-use it.

They're not hard carbs to rebuild. Just take your time, take pictures if needed. Once you get it all back up and running, dial it in, and down the road you go.

Originally Posted by flyingtim01

The carb number is stamped (not cast) into the side of the carb. It will either start with a '17' or if it's older, a '7'. If it's REALLY old, it may even be on a circular tag attached to the body of the carb.

Good information, I appreciate the help and I am not sure which one I am going to rebuild, probably the one that wasnt leaking around the linkage but I will still rebush the carb while I am in there. When I buy the rebuild kit is there something special I should ask for as far as the rebushing is concerned?

[GRX]

Cliff's Q-jet book .... well worth the admission price.


How to Rebuild and Modify Rochester Quadrajet...

[geezer#99]

Link for kits and parts.
http://www.quadrajetparts.com/

[luvbowties]

Originally Posted by tex_waco_usmc

OK, so I am working on trying to get a SB 305 running that has been set up for 2+ years. The history on the truck is simple. My fathers truck, turned my daughters truck after it sat at my house for 2+ years with my father saying I am going to fix it up... (We all know how that sometimes goes)... She ran good but was pumping fuel straight into the exhaust and backfiring and leaking out of the carb... 65 miles and I ran through 15 gallons of fuel (You do the math, LMAO) So, she got parked until we could get around to her. There she sat until my daughter decided she wanted the truck and dear old dad said "sure your dad can get that running good for you!" LMAO....

Went out yesterday and it has a Rochester sitting on top of it. When a little fuel was poured down the throat it leaked out on the passenger side front corner, I believe out of the vacuum port that is there. Wouldnt fire, but did choke a little bit. Slapped the Original Rochester back on her, that I could not remember what was wrong with it and poured a little fuel down her throat and fuel leaked out where the throttle linkage goes into the carb... LMAO, now I remember why we pulled it in the first place!

So I am going to attempt to rebuild one of these two carbs for this truck just to get her running! Im looking forward to it. Is there anything I should be worried about?

Here's a fairly exhaustive how-to for the quads, including pics that show where to epoxy. Doesn't show racing mods, but dunno any how-to's that even seem to know about 'the rest of that story'. This should help you make it run correctly, tho'. HTH, sam
>> http://www.vetteprojects.com/kstyer/quadrajet.htm <<

[tex_waco_usmc]

Ok, so I went to youtube and searched for how-to videos on rebuilding a carburetor. (Im a hands-on/visual learner...show me once or walk me through it and I am good after that) Anyways, I ran across this link

http://youtu.be/us0mfq6q2KU

The link is to video 1 of like 9, you can find the rest of them real easy. This is a quadrajet off of a boat with a Chevy SB in it. But, this has got to be one of the best step-by-step videos I have seen yet! This guy was very thorough and his camera footage is great. I feel confident after watching all of the videos that I can get this quadrajet going again.

Thought I would share, in case some of you guys might need the same help I needed...

[geezer#99]

Here's a couple tips for you. A pic of how I work on my carbs. Works good if you have a vise. If not 4 equal length bolts will work as a carb stand.
Also watched part of his assembly. He hangs the needle with the little clip on the float wrong. If you put the clip thru the hole then the needle can hang up and flood. THe clip hooks over the back part between the holes. Commom mistake.
On page 4 of the link I gave you, you can see the correct wire clip location on the first pic.

[Stickman]

Originally Posted by GRX

Cliff's Q-jet book .... well worth the admission price.
X2 excellent book and he has all the parts you need

How to Rebuild and Modify Rochester Quadrajet Carburetors (S-a Design): Cliff Ruggles: 9781932494181: Amazon.com: Books

Posted via Mobile Device

[slikside]

Originally Posted by GRX

Cliff's Q-jet book .... well worth the admission price.


How to Rebuild and Modify Rochester Quadrajet Carburetors (S-a Design): Cliff Ruggles: 9781932494181: Amazon.com: Books

Absolutely! Can't say enough good things about Cliff and his book. Got a kit and primary shaft bushing job from him, then used his book to rebuild my carb. I couldn't be happier about how it turned out.

Originally Posted by tex_waco_usmc

Good information, I appreciate the help and I am not sure which one I am going to rebuild, probably the one that wasnt leaking around the linkage but I will still rebush the carb while I am in there. When I buy the rebuild kit is there something special I should ask for as far as the rebushing is concerned?

Check the julian dates on the two carbs, and choose the later model. Q-jets were being revised/updated throughout production, and the later models are much improved over the earlier versions. Even if the later one is in worse shape right now, ultimately I think you would be better off choosing it over the older model.......all of this learned from Cliff's book.

[69gmcc10]

Cliffs book is awesome! I picked it up at the local bookstore and read it in a day then read it again and it will be next to me as I rebuild my q-jet.