need new carburetor

[BJedi76]

I am in Alaska & my 1986 4x4 GMC Sierra Classic 1500 needs a new Quadrajet for it’s 305”. It has a 700R4 transmission.

The one I’ve got has had it and besides it’s the wrong carburetor. it’s for an older truck

I just want the proper one, but I’m having a little trouble figuring out exactly which one I’m supposed to have.

There seem to be several choices for this year.

I am not in California.
I am not in Canada.
I do not have a computer.

i’d like my fourth gear lock up to work and I’m pretty sure that has something to do with vacuum.

and I want flat head screw heads on my air screws. Not those stupid double D heads..!

I would appreciate any educated advice.

Thank you…

 

[75gmck25]

I currently use a Quadrajet 17080213 from a 1985 truck. It works fine, but a Quadrajet is not simple or fast to tune. Almost everything can be tweaked, but usually means removing the carb. I have been considering a swap so I can try some alternatives.

Assuming you have a budget:

I’ve read lots of good reviews for the Edelbrock AVS2. They are simple to tune like the older Edelbrocks, but seem to have great low end throttle response. A frequent comment is “feels like EFI off idle.”

I also looked at the Quick Fuel carbs, and they get good reviews. However, I’m not as familiar with how to tune them.

Bruce

 

[Ricko1966]

What carb number do you have now? The only thing funny about your factory q jet is it would have dual capacity accelerator pump other than that it's just a plain old qjet. If what you have is for a 305 with an automatic, I'd rebuild it and go. Throttle valve geometry for the 700r4 will be right , jetting will be right. Get your carb number let's see what your starting with.

 

[BJedi76]

17066559

...& it has the stupid double D air screws.

none of the auto parts stores carry the tool to adjust them.

I had to pay $50 off the Snap On truck for a cheap piece of crap tool that was not strong enough to turn the screw and when I applied pressure to it, it broke..!

I have called several Quadrajet specialists And they informed me that the replacement flat head air screws are not made anymore, so I cannot replace the double D screws, even if I could get them out.

i’m not sure if this is what was meant by it, but I was told on a Corvette forum that I had the “dreaded non-rebuildable” carburetor.

The carburetors that I have seen for the appropriate year for this engine, do not have the front pull off. I also wouldn’t have to worry about the extra capping off of the choke air intake.

also, whenever I give more than half throttle something gets stuck and fuel just pours out the sides of carburetor from the throttle pivot pins. It does the same “flooding” like the float or needle is stuck if i don’t warm the truck up ALL the way.

Is it too much to ask to simply help me determine which carburetor is most appropriate?

 

[BJedi76]

I don’t want an Edelbrock. They are square bore, whereas the Quadrajet is a spread bore, which means two things:

1. The primaries are the same size of the secondaries, so you don’t get as good fuel economy. The Quadrajet’s primaries are smaller than the secondaries, so if you stay out of the secondaries, you get quite decent fuel autonomy.

2. I would have to purchase a new intake manifold or use an adapter. I’d like to keep everything down where it supposed to be and I’m not looking for performance. I’m looking for best fuel economy.

 

[BJedi76]

Can someone tell me the difference between the R4M4MED 12355154 &
R4M4ME 17085220

I want a 600 CFM

 

[BJedi76]

I’ve noticed that some Q-jets have only the front pull off and some only have the rear pull off, And some have both front and rear Pull offs.

Can somebody explain this to me please?

One of my problems with my current Q-jet is that in the winter, if I depress the throttle around halfway or more, the pull offs don’t let the throttle slam close and keeps fuel going into the carburetor, which in turn keeps power to my wheels and I do A lot of tire spinning on the snow and ice.

this is annoying and dangerous.

 

[BJedi76]

it also does the same “flooding“ type thing (like the float or needle is stuck) if I try to drive the truck before it is COMPLETELY warmed up.

 

[Bextreme04]

It sounds like rather than having the wrong carburetor, yours is just in REALLY bad shape. I would suggest either sending the carb you have to an experienced rebuilder to have it fully redone, or go to a specialist site such as https://quadrajetparts.com/rochester-quadrajet-c-128.html to get quality replacement parts. The pull-offs should never be holding the throttle at all. The pull off on the front should only pull the choke flap open a tiny bit when the engine is cranking to allow it to start. After that they do nothing.

That site also has replacement idle air screws to replace your double-d screws with either flat head or hex head screws.

These guys are also top notch and have lots of experience. https://cliffshighperformance.com/ . They have a forum with LOTS of useful information as well. I would suggest calling cliffs and see if they can tell you what carb number you SHOULD have. Have the number handy for the carb you DO have as well. They will be able to either sell you the parts to repair the one you have if it is the right one, or they can probably find you the right one if it isn't.

 

[Ricko1966]

17085226 is correct for your truck.But it won't have the idle screws you want.Your carbs acting stupid because it needs rebuilt.

 

[Matt69olds]

You can use a cutoff wheel or hacksaw to cut slots in the double D air screws to use a flat blade screwdriver to adjust them

 

[BJedi76]

If I was able to get the Double D screws out, I would be able to just adjust them.