Quadrajet Clarification

[firebane]

Alright guys I'm looking for some clarification on what on earth my Qudrajet is and could perhaps be a reason to some of my problems with the truck.

So extensively searching google you'll come upon many websites that help decode what type of Qudrajet you have. I went outside and wrote down the numbers that they refer to and this is how it broke down for me...

I should also mention my truck is a 1974 with a 350 and a TH350.

Qudrajet Model: 17081291

1708 = 1980s
1 = Manufactured in 1981
2 = Federal Standards
9 = Holden?
1 = Manual

So the first few things that come to mind is what on earth is Holden? According to my google search this is an Australian variation of the GMC vehicles. The other thing of importance is the "Manual" designation.

So with all this information would the general consensus be that its amazing my truck runs at all with this carb? I should also mention the secondary choke pull off looks like this and has two vacuum ports (http://contentinfo.autozone.com/znetcs/product-info/en/US/wl2/CP229/image/4/) wondering if someone could shed some light on to this.

Thanks

 

[MadOgre]

First of all a picture is worth a thousand words ? got any ?

Secondly what choke style do you have on that carb ?

A manual designation or different choke configuration has nothing to do with how the carburetor performs vs your would be stock set up.

virtually all rochesters from the beginning with the divorced choke to the later models with electric choke are essentially the same carb with a flow rate of 750 cfm. late later years incorporated electronics into the carb and they are another issue all together.

Somebody probably grabbed a junk yard donor for your truck at some point in time.

It probably just needs a rebuild as all quadrajets do from time to time.

some pics would greatly help.

 

[MadOgre]

Also you should list exactly what your problems or issues are, that you are having with your truck.

 

[HotRodPC]

Holden is an auto manufacturer in Australia. They are in bed with GM on many of their cars and vice versa. Most have GM PowerPlants. The lastest GTO's for example, were actually Rebadged Holdens. I here there is a Holden model that may be coming to US in 2015 or 2016 as the New Chevrolet El Camino too. The Chevelle may also come back which could possibly be the Pontiac G8 rebadged as a Chevrolet.

 

[firebane]

I'll take a picture later as it was late last night and getting dark.

It'll be easier to point stuff out then.

 

[firebane]

As requested here are the pictures of the carb and I even verified today if that "9" was a name and yes it was.

So perhaps this will help in clarifying what type of qudrajet is on this thing.

I should also mention the thing on the back left of the carb has two vacuum ports.

Oh also based off the pictures I know it maybe difficult but could anyone perhaps recognize the type of intake being used?

 

[MadOgre]

Looks like a stock cast iron intake manifold as it says firing order # in front of the carb.

So it just happens I have the exact same carburetor except it is for an automatic and the only difference I can tell is that you are missing the inner throttle linkage/bracket that you would attach your kick down cable to, the spot you have it hooked to now is simply for the throttle return spring.

Aside from the missing kickdown linkage there is nothing wrong with that carb except it probably needs a major overhaul.

Most likely suffering from leaking fuel well plugs, worn throttle shaft plate and the usual rebuild that they all need every few years.

If it sits for a few days do you have to crank it a few times or pump the throttle to get it to start ? if so leaking fuel well plugs are to blame.

does it have an eratic idle, kinda like a vacuum leak ? if so worn throttle shaft plate.

If your having down shifting problems it probably has to do with where your kick down cable is located on the carb. Which you would need to just find an automatic carb or completely disassemble your throttle plate shaft and install the correct linkage. which would be an excellent time to have throttle shaft bushings installed.

The alternative would be to buy an Edelbrock carb. but you do need an adapter plate and some special fittings unless you just cut the factory steel fuel line and use the compression fitting that edelbrock supplies in their fuel line kit, the rubber hose one. You will also need a pressure regulator( this is a must with eddy carbs ) And you need to install a fuel filter in ther some where too.

 

[lusktommy]

I here there is a Holden model that may be coming to US in 2015 or 2016 as the New Chevrolet El Camino too. The Chevelle may also come back which could possibly be the Pontiac G8 rebadged as a Chevrolet.

that would be sweet depending on how they look

 

[firebane]

Looks like a stock cast iron intake manifold as it says firing order # in front of the carb.

So it just happens I have the exact same carburetor except it is for an automatic and the only difference I can tell is that you are missing the inner throttle linkage/bracket that you would attach your kick down cable to, the spot you have it hooked to now is simply for the throttle return spring.

Aside from the missing kickdown linkage there is nothing wrong with that carb except it probably needs a major overhaul.

Most likely suffering from leaking fuel well plugs, worn throttle shaft plate and the usual rebuild that they all need every few years.

If it sits for a few days do you have to crank it a few times or pump the throttle to get it to start ? if so leaking fuel well plugs are to blame.

does it have an eratic idle, kinda like a vacuum leak ? if so worn throttle shaft plate.

If your having down shifting problems it probably has to do with where your kick down cable is located on the carb. Which you would need to just find an automatic carb or completely disassemble your throttle plate shaft and install the correct linkage. which would be an excellent time to have throttle shaft bushings installed.

The alternative would be to buy an Edelbrock carb. but you do need an adapter plate and some special fittings unless you just cut the factory steel fuel line and use the compression fitting that edelbrock supplies in their fuel line kit, the rubber hose one. You will also need a pressure regulator( this is a must with eddy carbs ) And you need to install a fuel filter in ther some where too.

Good info thanks! Would you mind taking some pictures of yours for reference for me? I also have 2 other qudrajet bodies that came with the truck that I will be taking a look at this weekend to see what versions or variations they are and perhaps will end up making a frankenqudrajet out of all the parts.

The truck if I leave it sit actually starts up fairly good but won't idle worth beans and will die within a few seconds unless I hold the throttle open a bit and thinking this is something to do with the choke.

Other issue I think is as you say relates to the leak back and that is that if I do drive it during the day eventually it will get to a point where it won't start unless I hold my foot to the floor which as you point out seems to be the leaky problem.

Now that I know the particular model of this I can order a rebuild kit for it or hopefully the other 2 I have is meant for an automatic transmission. This particular one I have now strangely does kick down ok but could perhaps be better.

 

[MadOgre]

Good info thanks! Would you mind taking some pictures of yours for reference for me? I also have 2 other qudrajet bodies that came with the truck that I will be taking a look at this weekend to see what versions or variations they are and perhaps will end up making a frankenqudrajet out of all the parts.

The truck if I leave it sit actually starts up fairly good but won't idle worth beans and will die within a few seconds unless I hold the throttle open a bit and thinking this is something to do with the choke.

Other issue I think is as you say relates to the leak back and that is that if I do drive it during the day eventually it will get to a point where it won't start unless I hold my foot to the floor which as you point out seems to be the leaky problem.

Now that I know the particular model of this I can order a rebuild kit for it or hopefully the other 2 I have is meant for an automatic transmission. This particular one I have now strangely does kick down ok but could perhaps be better.

I don't think its a choke issue. usually a choke issue revolves around high revs that wont come down to idle. Or it never works. which is maybe what you mean lol

The foot to the floor is from hot soaking. so when you run it and then leave it for 30-45 min its a freakin pain in the asss to start. There are multiple reasons that contribute to hot soak.

Hot soak is where your fuel bowl is heated to the point that it creates enough vaporization pressure that it pushes fuel out every passage that it can and flooding your engine. It also can be caused by having already high temperature fuel being delivered to the fuel bowl.

base insulator problems, cast iron manifold doesn't help either, high float setting, needle and seat issues, boiling gas by having fuel lines too close to heat sources. or high fuel pressure. although not usually a problem with quadjets and stock mechanical fuel pumps.

The thing is ive never seen a quadjet of your era having slotted straight blade screws, usually its only the older ones with the divorced choke that used those, all the later model ones used tourqe bit screws. So I wonder if someone didn't already monkey with it.

 

[MadOgre]

So to start you need to check your throttle shafts for wear by grasping them at the end and moving them up and down forward and back to see if you can feel any play between the shaft and the bore that it rotates in. Were not talking about rotating them. We want to see if there is any play in tolerance/slop between the shaft and its bore.

if you can feel some movement between the two then it is worn beyond tolerance. FYI it is the aluminum base plate that wears not the throttle shaft. This wear will allow a vacuum leak below the throttle plate and will seriously disrupt your carburetor from functioning.

When you find a good one then that is the one you want to rebuild. Preferably an automatic one.

Although the base/throttle plates can be removed separate from the main body there are subtle differences from quadjet to quadjet so unless you have two identical base/throttle plates they are not interchangeable.

Ill get some pics for you.

 

[MadOgre]

Oh ya. Another thing im wondering is which vacuum port on your carb is the vacuum advance from your distributor connected to ?

 

[HotRodPC]

Oh ya. Another thing im wondering is which vacuum port on your carb is the vacuum advance from your distributor connected to ?

NO COMMENT, NO COMMENT !!!

 

[MadOgre]

What LOl ???

 

[MadOgre]

NO COMMENT, NO COMMENT !!!

What are you saying there is no vacuum advance ? on a 74. I thought all HEIs had vacuum advance.