Q-jet

[Tsoptich83]

I am having some issues with the truck starting. I replaced the plugs, cap, rotor, wires and fuel pump to bring it home. I also drained the old gas out of one tank and added 5 gallons of new gas to get it home. I believe I have tracked it down to a fuel issue. When it ran to get home it died a couple times. I have been looking and if I understand correctly there is only one fuel filter, and its at the intake on the carb (circled)? And if so is it acceptable to able another inline filter? And if so should it be pre pump and since there are 2 tanks do you add one inline for both tanks? I am also thinking that it couldn't hurt to rebuild the carb. Any kits that you all could recommend? I see that O'Reilly's offers a kit, as well as summit and jegs. I kind of want to keep the Q-Jet it has a cool factor to it as well as a from what I read they are decent carbs. I should I that you can see some open and cracked vacuum ports on the carb. They have been caped and replaced.

[1968k20]

I usually see filter before and after the fuel pump. Also, I see all of the vacuum lines disconnected in the photo. It would definitely not run real well at idle.

[Dead Parrot]

Looks like a PO did an emissions delete by simply yanking vacuum lines. At some point, you probably want to either finish the job or restore it to original.

If the carb ports are plugged or connected, the next suspect is a poorly adjusted choke. Should be closed or mostly so for a cold start. Each motor seems to have a preference. Adjust by rotating the black thing on the side of the carb after loosening the 3 screws. (if still rivets, you have to drill out and replace with screws, pretty sure there are how-to threads on forum).

There is supposed to be a filter in the circled area. Worth checking to see if it joined the missing emissions hoses. There is also one at the base of the sender/pickup assembly in each tank.

I run a Fram G3 type filter on the hose between the frame and fuel pump intake.

[cadillac_al]

Go ahead and check the filter. The carb already looks cleaner than the rest of the engine. It has probably had some attention recently. A Chevy V8 only needs one vacuum line to the distributor to run fine. It's most likely a choke adjustment making it start hard. My Chevys always start hard if they sit for a week. The gas in the carb disappears somewhere. If I drive them every day they fire right up.

[jwilson645]

I highly recommend ordering your rebuild kit and the rebuild book from Cliff Ruggles at www.cliffshighperformance.com . He is a guru of Qjets and his kits are top notch with ethynol compatible parts.

[SilverMiner]

Originally Posted by jwilson645

I highly recommend ordering your rebuild kit and the rebuild book from Cliff Ruggles at www.cliffshighperformance.com . He is a guru of Qjets and his kits are top notch with ethynol compatible parts.

Yes, this X2!

Tsoptich83 - Cliff Ruggles kits are the only way to go if you value your peace of mind and don't mind spending a small amount more for quality. Doing a basic rebuild of a Qjet isn't rocket science and doesn't really require any special tools, but it can be a bit fiddly. If you are at all interested into diving deeper into Quadrajet tuning and optimization, buy Cliff's book and log on to his excellent highly informative forum at www.cliffshighperformance.com

The carb in your photo looks suspiciously clean, so I'd guess somebody has been into it within the past couple years if not sooner. If you don't know the history of the rig, you might want to throw a kit into it if only to confirm proper float height and correct primary rod engagement which are two items that frequently can go wrong with an improper rebuild.

But before diving into the carb, you should probably confirm that all of the vacuum hoses are in good condition and connected properly. It is surprising how much a single open vacuum port can screw things up and make the engine run horribly. Even a small leak around the base gasket can make a difference, particularly at idle. The photo indicates somebody has already stripped and bypassed the EGR and TVS systems, so really the only small vacuum line to the carb should be the one from the distributor vacuum advance. The large port exposed on the front above and to the right of the fuel inlet is intended to be plugged into an evaporative fuel canister which may or may not still exist. I can't remember if leaving that open causes many headaches, but it can't hurt to either connect it or plug it off.

[Tsoptich83]

Thanks guys. I do not not know if the carb has been gone through or not. But it looks clean. I see that most of the emissions stuff is gone or disconnected although the canister is still there. I will look in to the choke adjust ment as well as the filter. I think I had happened across Cliffs website and poked around a bit making my choice to keep the Q-jet. I will look into all the suggestions. Thanks.

Thomas.

[geezer#99]

If you check the filter in the carb inlet go slowly when you remove the fitting from the carb.
It’s fine threaded and easily stripped.

[Tsoptich83]

I will thank you.