Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

1967 - 7027240 - Fuel Inlet Upgrade - Needle and Seat Kit

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65WildCat:
Early Q-Jet Needle and Seat Upgrade Kit - 7027240

Question - I have installed the long brass tube with o-ring from the upgrade kit put the two screws in and dropped the needle in where the old plunger valve was.
The kit comes with a third small brass piece with o ring. as in the pictured in the book.
Is this another type of early upgrade seat for another carb?

I have installed this piece upside down - O-ring facing down in the plastic baffle hole to block off the fuel inlet when installed. So all fuel should enter thru the new needle and seat.
Is this correct or am I just trying to use all the parts with the kit?
Thanks for the confidence. First time Q-Jet User and Rebuilder.

Cliff Ruggles:
Not sure about the third part.  Our kits for the early units include the updated fuel inlet seat assembly and the "O" ring plug for the fuel supply hole.

We don't build many of those carburetors or sell too many kits for them, other than once in a while doing a complete stock restoration. 

They are fine once upgraded, but most lack the secondary POE system, and the small fuel inlet seat assembly and poorly located float fulcrum is not the best set-up for high performance work.

I hope that you leak checked and sealed the bottom plugs?  Never had one in here  to date that didn't leak.  It probably needs shaft bushings as well, most units we've worked on here were pretty loose at the primary throttle shaft.

The early units are still good enough for at least 400hp with the upgraded parts, maybe even a tad more with a good fuel delivery system.....Cliff

65WildCat:
Just a stock rebuild carb for a 66 Buick 425. Factory 340 HP with the single small Carter Carb. Should do a bit better with the Q-Jet. Figured early stock q-jet should get better fuel economy and off course already has the correct linkage hook-ups for my app.

I have Re-Bushed the Shaft and Plugged the wells. A few of them were already popped out when i opened it up. So I just made screw plugs and JB weld for all of them... Just following along with your book.

Not to sure what I'm Doing - But that's how you Learn

Comes off idle fairly nice - No tire smoke show
But when I mash it - not all that spectacular - still playing with the set screws - idle - and timing....

As far as the small extra brass piece it's seems to fit in that hole in the baffle just perfect. Effectively blocking off the original fuel inlet. so all fuel now flows thru the new needle and seat
Just worried about fuel starvation if the new needle seat can't handle highway speeds....
Guess the only way to know is Take out for a long ride and work the kinks out.......

Cliff Ruggles:
JB Weld is not effective at holding back fuel, at least if it's dabbed on.  It may work better trapped by the threads of the screw in plugs.  Marine Tex or Devcon are the only two epoxies that we could find that did not "soften" in the presence of gasoline.  I thought I mentioned this in the book?  Anyhow, good luck with the new carburetor.....Cliff

65WildCat:
Don't Recall reading anything about what epoxy to use or not in your book. I do admit it's a lot of information for the first time user to take in. Maybe I'll be redoing the epoxy after a 1400 mile run up the east coast --- If I make it. After a week in light test service. It does seem to run dry all ready. I thought it was just flowing back out the fuel inlet to the tank. External Filter, none in the housing, no check valve. And that would also mean a leaking needle and seat. Live and Learn...

After Dialing In - kick down linkages, Timing and idle to stock and for best vacuum. I get the slightest of hesitations light throttling from a stop light. And after sitting at idle in traffic or stop light slight hesitation and it bucks like its running out of fuel for a moment once in a while. Slow mechanical fuel pump action at low r.p.m.s.  I guess. Or maybe all my fuel just dumped down the plugs while sitting at hot idle. Can that happen?

Other than that --- Runs like a champ

Will the JB Weld screw up the internal passages as it softens and possibly clog something up?
I'm sure I was on the heavy side coating the threads and underneath the plugs.

Anyways, Not Bad for a Campground Table Rebuild with basic hand tools. Other than the Epoxy part....
Thanks Again -- And so Far I'm pretty happy with my new found performance..... I'll know about the economy part while cruising 1400 miles -all highway- watching my vacuum gauge all the way. And hoping something else don't break along the way...........
Jim

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