Quadrajet Build Thread

olds307 and 403

Geezer
Thread starter
Oct 14, 2008
7,471
113
Melville,Saskatchewan
So my poor temporary Olds 350 didn't stand a chance in surviving. Not only did I have an issue with the Mallory distributor, now replaced with a HEI, I had an issue with the supply to the distributor. The connection came apart, so I upgraded to a bigger gauge wire and soldered the connection, 12 volts at the distributor. I thought the ignition was the flooding issue over half throttle, nope. Something is up with this Everyday Performance tuned and rebuilt Qjet,17058250, a 78 Oldsmobile 403 carb. It has been used for at least 5 years and has worked well other than choke linkage issues which required replacement to fix. I talked to Cliff Ruggles and ordered a SR kit which comes with a float, the secondary air door cam and spring. I also ordered his better 44 primary rods, he knew the carb came with 73 jets. I also ordered a power piston spring from Cliff. I know Ken used different primary rods than the factory 44K rods since I put 72 jets in it, that makes sense. I made the APT slotted and adjustable with a removable plug in the air horn before I sent it to him. I idled so much better when it came back. Cliff Ruggles had nothing good to say about carbs he saw built by Everyday Performance, which I was surprised by. He said expect a ball point on spring under the power piston and the rod hangers severely bent and the float way off😳. Ken told me he rebushed the secondary throttle shafts, I will do the primary throttle shafts since Cliff's kit came with enough to do two carbs. I am really curious to open this carb now, maybe Cliff got a bad one?
 
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olds307 and 403

Geezer
Thread starter
Oct 14, 2008
7,471
113
Melville,Saskatchewan
I recieved the SR kit with Cliff's 44 primary rods and his choice for a power piston spring, the orange one for my 78 403 800 cfm carb done by Everyday Performance. I will be doing the primary throttle bushings and air door cam. It will be interesting to see if any of what Cliff said was true or just one bad example of an Everyday Performance Qjet. I will be doing this next weekend. I also didn't like my attempt on the custom bent 3/8" Ni Copper line I used. The Ni Copper brake lines were amazing to work with, the larger line kinks much easier and I need a couple of tight bends. I will pick up 2 this week and really take my time to get nice bends.
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olds307 and 403

Geezer
Thread starter
Oct 14, 2008
7,471
113
Melville,Saskatchewan
I pulled apart the Everyday Performance built Qjet. Other than choke linkage issues, it has been good for years but is now flooding under hard throttle. Nothing glaringly wrong other than a couple of things. No clip on the needle for the float, maybe the issue. The power piston arm is a little bent, not as severe as Cliff has seen. The power piston spring is stiff but it was tuned for a mild cam. I could not make out what the primary rods were. He did put in a decent accelerator pump.
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olds307 and 403

Geezer
Thread starter
Oct 14, 2008
7,471
113
Melville,Saskatchewan
I changed the air door cam and spring, there was some wear.
20210615_210840.jpg

I also opened up behind the idle mixture screws, Ken opened them around .075, Cliff suggested .080 to .100" depending on calibration. I upped them to .092" size drill bit, next size was around .074". I am not adding bypass air, I am keeping the hot air choke and using the Performer manifold with a 1" open spacer. The RPM intake is probably better choice but I don't want this Performer sitting on the shelf. I pulled the primary throttle shafts, there is bronze bushings in the primary side. They don't look too worn, not sure I want to fight them out. There is minimal play, the new bushings look the same size and slop as what is in there. The idle and main air bleeds, all 3 are around .070". I will try and measure the idle tubes and idle channel restrictions tomorrow.
 
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olds307 and 403

Geezer
Thread starter
Oct 14, 2008
7,471
113
Melville,Saskatchewan
Well, I did a couple more measurements. It is hard to tell the idle tube size but Ken enlarged the idle channel restrictions to around .055" right around where Cliff suggests. My .092" holes behind the mixture screws didn't hurt a thing, helped if anything. I also installed 73 primary jets and Cliff's 44 primary rods, I had the APT set at 7 turns from seated, I went to 8. I set the float at 1/4" drop per Cliff's suggestion. I think this carb was dropped on it's side at one point and slightly mushroomed where the bolt goes in for the choke housing. It causes the housing to pull too tight against the main body. I added a small washer between the housing and main body. I used the linkage Cliff sent me the rod from the pivot link in the main body was bent and not allowing full choke closure. I went to start it, it fired right up, the choke linkage stuck on. I backed the screw off a hair on the choke housing, seemed to fix it. It definitely idles smoother in gear. I turned the idle mixture screws 2.5" turns from seated and never touched them after. Flooring it or anything over half throttle caused stalling and flooding out, no longer. The air door needs tightened up a bit but much better, just a slight bog. Once I get my wideband I can it bang on for the new 358.
 
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PBGBodyFan

G-Body Guru
Supporting Member
Mar 3, 2009
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Wisconsin
I always wanted to dig into a Q-Jet but still haven’t. I sure hope Cliff keeps providing his service, I’m tempted to have him go over mine that he rebuilt about 9-10 years ago or maybe just send him another one so I have two good ones.

Maybe I can learn a thing or two in this thread.
 

olds307 and 403

Geezer
Thread starter
Oct 14, 2008
7,471
113
Melville,Saskatchewan
I also wanted 2 good Qjets around, one mild, the other more wild. It will be interesting to see where it stands according to a wideband.
 
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