did I make a mistake converting 3x2 to QJET

[Dale P.]

this has been a challenge so far. finding a good used 69 427/390 intake (EASY) . buying a rebuilt 68 427/390HP QJET (easy) .. THEN starting to do the fuel lines and fuel filter everything went south .. I finally came to the point I realised the need for a fuel return line to the fuel tank ... I am in a bind since I started with a 427/400HP car .. MY CAR DOES NOT HAVE A FUEL RETUN LINE ... so guys what are my options I understand the QJET MUST have a fuel return line (either pump to tank or fuel filter to tank) or it will flood out. A holley will be OK without the fuel return line but will not fit under the hood.


link to carb being used on an 801 intake with what I think is correct fuel pump for 427/400HP

http://www.summitracing.com/parts/HLY-64-7097/

[Edward J.]

Re: did I make a mistake converting 3x2 to QJET

Dale, that maybe a problem since the factory may not of made provisons for a return line on the fuel tank. is there a vent pipe on your fuel tank? maybe a possiablity.running a metal line to tank wouldn't be impossiable, but may require sectioning the line at frame kick-up area.

[Jim T.]

Re: did I make a mistake converting 3x2 to QJET

Dale I need to learn why having a QJet replacing the 3X2 requires a fuel return line?
My 70 has a fuel return line as well as my 68. The 68's return line is from the fuel filter to the tank. The 70's fuel return line is from the fuel pump to the tank.

[Clem Z.]

Re: did I make a mistake converting 3x2 to QJET

this has been a challenge so far. finding a good used 69 427/390 intake (EASY) . buying a rebuilt 68 427/390HP QJET (easy) .. THEN starting to do the fuel lines and fuel filter everything went south .. I finally came to the point I realised the need for a fuel return line to the fuel tank ... I am in a bind since I started with a 427/400HP car .. MY CAR DOES NOT HAVE A FUEL RETUN LINE ... so guys what are my options I understand the QJET MUST have a fuel return line (either pump to tank or fuel filter to tank) or it will flood out. A holley will be OK without the fuel return line but will not fit under the hood.


link to carb being used on an 801 intake with what I think is correct fuel pump for 427/400HP

http://www.summitracing.com/parts/HLY-64-7097/

the Qjet does not heed a return line to relieve the pressure as that was a emission problem they were trying to cure. you can not use a return line fuel pump with out a return line as there will be too much fuel pressure because the return line is a calibrated leak on the pressure side.

[Dale P.]

Re: did I make a mistake converting 3x2 to QJET

so am I understanding this correctly .. 1) leave the current non- return fuel pump installed (orginally a 427/400HP pump) ,,,2) install the fuel lines (correct for a 427/390 HP) and 3) add a NONE fuel return in line filter where the normal AC GF-432 filter would normallt go 4) tube up to the carb .. start up and enjoy the car?

I always thought that the fuel return line was a requirement becuase the QJET would flood out without it and it had nothing to do with emissions .. at least that is what I have read before.

[Clem Z.]

Re: did I make a mistake converting 3x2 to QJET

so am I understanding this correctly .. 1) leave the current non- return fuel pump installed (orginally a 427/400HP pump) ,,,2) install the fuel lines (correct for a 427/390 HP) and 3) add a NONE fuel return in line filter where the normal AC GF-432 filter would normallt go 4) tube up to the carb .. start up and enjoy the car?

I always thought that the fuel return line was a requirement becuase the QJET would flood out without it and it had nothing to do with emissions .. at least that is what I have read before.

there were lots of Q jet carbs out there without a return line pump. with this new ethanol fuel you may have other problems from the heat so i would plug the the holes in the exhaust heat groove if your manifold has them.

[Timothy B.]

Re: did I make a mistake converting 3x2 to QJET

Dale,

I understand you are involved in this job allready but what is wrong with the Holley's.

[Dale P.]

Re: did I make a mistake converting 3x2 to QJET

my main issue with the Holley's is the constant hard start when cold .. constant fuel weeping from the center carb, then lastly flooding when hot .. also could never keep the float adjusted. it was rebuilt twice, but with no luck. maybe if I could find someone to do a true "great" rebuild I would put them back on.

just as a side note the center is orginal to the car .. the two out boards are vintage 69 .. so if I would go that way I would just go ahead and find two correct out boards and rebuild everything

[Paul J.]

Re: did I make a mistake converting 3x2 to QJET

Dale,

You're probably doing this for drivability, but I'm with Tim. Unless you have some sentimental attachment to the car maybe you'd have less aggrevation if you'd find the car you really want.

Just my 2 cents.

Paul

[Dale P.]

Re: did I make a mistake converting 3x2 to QJET

the entire change over is driven because I love the car but it is really hard to drive and feel comfortable knowing the issues with the 3x2 set up. when they are fresh and adjusted it runs great but when they start to go south it happens in a hurry and the last time I just prayed until I got it home .. and barely got it into the garage. the center carb was flooding again. so I had enough ... thought that going to the QJET will get me where i wanted to be ..

[Clem Z.]

Re: did I make a mistake converting 3x2 to QJET

the entire change over is driven because I love the car but it is really hard to drive and feel comfortable knowing the issues with the 3x2 set up. when they are fresh and adjusted it runs great but when they start to go south it happens in a hurry and the last time I just prayed until I got it home .. and barely got it into the garage. the center carb was flooding again. so I had enough ... thought that going to the QJET will get me where i wanted to be ..

the holley can be fixed to work but just a rebuild kit is not the answer as the parts must be straigtened and machined to removed the warpage caused by people over tightening the bowl screws to stop leaks

[Timothy B.]

Re: did I make a mistake converting 3x2 to QJET

I agree with Clem.. I have never done 3x2 holleys but have been playing with holleys since mid 70's.

The engine for the most part runs on two barrells, I suspect all three carbs need to be flatened and throttle shafts bushed. Also, the throttle plates on the two outside carburetors probably need to be adjusted/sealed in closed position to the base so no vacuum leakage at idle. The center carb has idle circuit so the blades are open some.

There is some good info in archives on holley's as we all have been down that road with these carburetors.. Also, great suggestions from people here always willing to try and help..

I understand how you feel about always having to fool with these Holleys and really don't blame you for wanting to switch, but if that were my 68 I'd fix em..

[Michael W.]

Re: did I make a mistake converting 3x2 to QJET

I always thought that the fuel return line was a requirement becuase the QJET would flood out without it and it had nothing to do with emissions .. at least that is what I have read before.

I was always told that the return line was to minimize the possibility of vapour lock in the fuel pump by continually circulating cool(er) fuel from the gas tank. Qjets without return line fuel pumps (two port pumps IAW) might have a lower output pressure than a three port pump where someone has blocked the return port.

Try measuring out put pressure of your existing pump and if less than 6-7 you should be OK.

[James H.]

Re: did I make a mistake converting 3x2 to QJET

I too was faced w/ the same delema.. I returned my edelbrock carb and intake and got the tripowers rebuilt and dialed in. Glad I did.. runs like a top now.. Also got a hot tip from JohnZ on how to replumb the vacuum lines that kick in the tripowers. Big difference in responce.. I did to both my 67 and 68. Good luck with your desicion.
I think if I was going to convert to a single, I'd make it an L88 set up..