Looking for original quadrajet for 1977 C10 350

[Steppin Razor]

Hey all.  I have a 1977 C10 with a 350, auto that had a Holley carburetor on it when I bought it .  I keep having the same problem rebuild after rebuild so I want to go back to the orginal carb, but I don't know what I need.  Will this fit? https://www.carburetorcenter.com/product-page/1974-1978-chevrolet-rochester-quadrajet-carburetor-remanufactured
 I've got no core to send in, so I'd like to keep the cost down.

Alternatively, I could go with an edelbrock, but I don't know if the adaptor plate for the Holley will also fit the Edelbrock, or do I need to buy an adaptor as well?
Thanks

[SilverMiner]

My posting history here and on other forums will show that I am an outspoken QuadraJet fanboy and often recommend that folks put in the time and effort to use them. I honestly believe they are the best carburetion solution for our trucks.

HOWEVER, in your case I'm not so certain of that given you are not starting with access to the original carb. One of the fatal quirks of QuadraJets is that nearly every one was specifically calibrated to a particular engine combo, and this is why so many folks were disappointed back in the day when they attempted to swap carbs they'd acquired from a buddy willy-nilly onto their freshly hot-rodded small block.

It could be unfortunate that a previous owner ditched the QJet, but let's assume they did so for good reason. It sounds like they cheaped out and didn't also swap the out the original spread-bore intake and instead opted for an adapter plate to use the the Holley. This same adapter should also work for an Edelbrock unless the Holley is some crazy giant Dominator style drag-racing carb.

You could go on a long and potentially expensive hunt for an un-molested (NOT REBUILT or REMANUFACTURED BY A NATIONAL CHAIN) core, but I'm guessing all you really want is to have a truck that runs well. The Holley can accomplish that and so can the Edelbrock. It comes down to how much time and money you want to spend to achieve your goals. In todays day and age you are more likely to find a shop comfortable with rebuilding or tuning either the Holley or Edelbrock than finding one that has experience dealing with the unique attributes of the Qjet. Or is this something you'd like to tackle yourself?

What is your goal? Do you know if the engine has been modified much past stock? More information will provide better answers - there a lots of smart folks on this board.

[Steppin Razor]

Thanks for the reply.  My goal is to get it on the road.

My suspicion from the conversation I had with the previous owner was that he swapped it out as a 'performance' modification.  The Holley carb he picked is the bottom of the line offering.  I think he got it from Summit Racing, but don't know for sure.

I developed a problem with it after a few months of ownership, which after much investigating, discovered that fuel from the rear bowl was being siphoned into the venturis and drowning it in fuel.   This is my first carburetted vehicle so I got my engineer friend to help (he's owned old cars for decades).  Took it apart, examined for leaks at the adaptor plate, cleaned parts, rebuilt it and everything was fine for a while, until I took a couple of one hour drives and it happened again.  Took it apart and rebuilt it again, bent the fuel float arm a little, made sure all the ports and passages were clean, fine for a while and then again, same problem.  I'm not interested in cleaning and/or rebuilding the dang thing every month.  My friend went over the thing with a fine tooth comb and speculated maybe there's some tiny crack not visible to the naked eye. 

So I need a different carburetor.  I understand what you're saying about the calibration issue if I got a quadrajet, I've read that before.  And there are so many combinations, with people using Chevy part numbers and rochester part numbers to make the muddy waters muddier.  I guess that means Edelbrock makes more sense to get this truck back on the road.  I just need to learn what all I need to do the swap, because these days (and for most of my days) I can't find a shop that both knows what they're doing and does it honestly.

Looking at this one for the edelbrock
https://www.autozone.com/fuel-delivery/carburetor/p/edelbrock-carburetor-with-electric-choke-1906/90396_0_0

[Rapid Roy]

I had an Edelbrock 1406 on a 72 C10 350 that worked well. I have a 1406 that needs rebuilt. I was going to replace the qjet but, decided not to do that.

Where are you located?

[LILT77]

If it's a stock build just trying to get the thing running and reliable, I would recommend the 1906 and 1406 (600cfm). The 1406 may be a hair cheaper as well.

[bd]

Your description of symptoms is reminiscent of a fuel inlet needle not seating properly - perhaps due to fine debris introduced from the fuel lines and tank or an improperly installed inlet needle, depending on the design.  If that's the case, replacing the carburetor may not solve the problem.  You should determine the actual cause as best you can and then formulate a repair strategy.  Have you examined the fuel filter element for contamination?

[Steppin Razor]

@bd: We examined the needle and seat, cleaned parts with both carb cleaner and an ultrasonic cleaner.  I have a new (clear) fuel filter inline. [Edit: also cleaned out the passages the fuel comes through. That's why we thought some micro crack in the housing.  Everything is sparkly clean, nothing was evident taking the carburetor apart].

@Rapid Roy: I appreciate it, but I need to get it back on the road asap, so I'll probably buy one so I can bolt it on and go

[bd]

How many floats - brass or nitrophyl?

[Steppin Razor]

In the rear bowl? 1 float, made of plastic.

[bd]

Nitrphyl floats are cast from closed-cell foam.  The foam can break down and begin to absorb fuel, typically but not always, forming small surface blisters.  If you gently squeeze the float or poke the blisters with a fingernail they will ooze fuel.  A float that absorbs fuel proportionately loses its buoyancy and sinks, causing the fuel level to rise.  Did you check the float for fuel saturation?

[Steppin Razor]

The float is hollow plastic.  We did check it for fuel inside, but it was fine.

[bd]

Metering block or metering plate?  Did you ensure that the fuel bowl is venting properly?

[TexasRed]

What is your fuel psi at? I've had a new Delphi pump put out 9 psi at idle and that can cause needles not to seat. 7 psi is usually the max you want to see.

[Steppin Razor]

Metering block or metering plate?  Did you ensure that the fuel bowl is venting properly?

Metering block was removed and cleaned.  Vents are the two small ports at the top, right?  Cleaned out those as well.

What is your fuel psi at? I've had a new Delphi pump put out 9 psi at idle and that can cause needles not to seat. 7 psi is usually the max you want to see.

We checked the first rebuild, I don't remember, but I think it was 6psi.  If the new carburetor doesn't fix it, then I guess a fuel pressure regulator is next, but I don't understand why it would work for a while after rebuild/clean, but then be a problem again if it's the fuel pump pressure.

[bd]

The fuel metering block may be warped.  Not an uncommon problem, generally the result of over-torqued fuel bowl screws.  New gaskets often hold for a few thermal cycles but then begin to bypass and leak.  If metering block warpage is the case, the block can be straightened in a press with careful application of pressure.  The blocks are soft and distort easily.  Fortunately, they also can be repaired fairly easily.