Projects Cutting my Hotrod Teeth (57 Chevy Budget build/revival)

eventually i want to put a better carb on it, but for now this quadrajet is the best carb i have laying around. it's gonna cost me way less to tune it and make an idler arm than it will to buy a new carb and intake. here's what i'm thinking. i think i'm getting fuel to the pump but the filter isn't staying full for some reason, i could be wrong but i've heard these glass filters don't always fill. i have to keep the rpm up so it'll stay running because it can't idle down as it is, so if i let off the gas, since the choke can't stay open, it kills it. the idler arm should solve both problems if my theory is right.

 

My youngest son Zach wanted a 67 thru 72 chevy truck. And I found one that they said was knocking and the bedside was caved in . cost $350. So we get it home and start it up and that knocking is a busted cracked flexplate. So I coach him and he using our transmission jack managed to unbolt the trans and converter and slide it back far enough to change the flywheel. Cured the knocking and the engine was a 305 from a 75 montie carlo. And it ran poorly smoked black smoke at idle and wouldnd idle below 1000 RPM. the timing chain was loose. So he pulled the pan and front cover and changed the timing chain. Ran better but still had carb issues. He asked me if I knew how to fix the Q jet. I replied I don't work on Q jets. You fix them with a BFH and beat them flat and sell for scrap. But being a know it all teen He bought a carb kit and took it apart. And he messed with that carb for weeks and never had any real success. But he was getting experience and I hoped he would actually get the Q jet working properly. Finally He pulled the intake and Installed the Intake and Rochester small base 2BBl carb from a 283. Like magic it ran good and idled perfect. And he now has a dozen of those 67 thru 72 trucks. And puts a bbl carb and intake on whichever he is driving.

 

Wire the choke open.






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Well i still am not getting fuel to the carb, it’s been cold so i haven’t wanted to work on it much but i went to a swap meet this morning, just to look around and i ended up having a guy give me some arm rests, (mine are very brittle and broken) and i picked up this intake/carb/air cleaner for $30. The stainless was too cheap to pass up but unfortunately it has a couple cracks. The quadrajet that was on the intake is foreign to me. I believe it has mechanical secondaries and it looks like a vacuum choke to me. Maybe someone will know more about it than me...

 

Glad to see you back on it. can't help much with the carb but maybe some of the parts can fix the one you have on the car. The black disc thing is the adjustable cover over a coiled thermactic spring that is heat sensitive, it needs a tube from the exhaust manifold drawing hot air into that coil to slowly open the choke as the engine warms up and it also lowers the high idle speed after you "kick" down the throttle. The cover is loosened and rotated to allow the choke blade to close to a certain position to allow a richer starting mixture. Takes a little patience if you don't have the book to go by. Your exhaust manifold should have a drilled hole all the way through to place this tube into. If you have a newer exh. mani without it then all this typing is for naught and you will have to go to a manual push/pull knob from the dash. Get at it!!!! Ralphie Edit, hood bar ends look good, throw the center away, better off with none than a busted one, people will think you did it!!

 

Its kinda odd but I never use the choke on any of my vehicles. I adjust them to where they are wide open. and when dead cold pump the throttle several times to let the accelerator pump get some fuel in the manifold. And we do have cold weather here. once its started I use the throttle to keep it running until its warm enough to idle.

 

Well i went ahead and put $17 into a new fuel pump to see if that was the problem. Not sure if it was or not but i have a new one on the engine now. I still cant get it to keep running but i’m going to wait until morning as to not bother the neighbors. I got fed up trying to get fuel to run from the tank all the way up so i took a 5 ft long piece of fuel hose and ran it into a jerry can. The glass filter filled wit fuel so i for sure have a working pump now. Tomorrow i’ll see if i can figure out how to get it to stay running. It’ll run if i keep my foot on it, and i put a zip tie on the carb to keep the choke open i guess i just have to let it warm up. I sure hope this is the weekend i get it to idle, then it’ll be onto brakes

 

Without going back and rereading, either fuel filter in the carb it's self is plugged up or the needle and seat is stuck closed or partially open. Look into those area's and let us know.

 

Will do!

 

I’m not familiar with QJet but if there’s fuel pressure but the engine is not getting fuel, I’d suspect either float set too low or mixture screws, but I’ve only played with Holley carbs


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You do have a push rod against the fuel pump lever? You can usually tell installing the pump as more often than not you have to fight the spring pressure pushing the pump to get the bolts started. They have been known to fall out if the flat plate is removed along with the pump, could have happened long before you got the motor!! Ralphie

 

OP had this to say. "I got fed up trying to get fuel to run from the tank all the way up so i took a 5 ft long piece of fuel hose and ran it into a jerry can. The glass filter filled wit fuel so i for sure have a working pump now."

 

I think the reason i’m not getting gas to the pump from the tank is because i don’t have enough fuel in the tank. I have the car level at normal ride height and about 4 gallons in it. I guess it could be the sending unit but its a brand new unit.

 

The sending unit only operates the gas gauge. It has nothing to do with flow of fuel from the tank to the fuel pump.

If you have 4 gallons in the tank, and the car is relatively level, you should have more than enough fuel in the tank.

I don't remember, but did you replace the fuel line from the tank to the fuel pump?

 

Yeah, completely brand new fuel system

 

So if it were me, I would disconnect the fuel line at the fuel pump, and put a piece of rubber fuel line on the line coming from the tank. Then I would take a shop towel or rag, and use it to help seal around the filler neck of the tank and blow compressed air into the tank and see if fuel is coming out of the rubber fuel line.....make sense?

Edit: You may need to temporarily seal off the vent tube if there is one while doing this.

 

I haven’t messed with a Qjet, so I can’t help you there, but I do have an Qjet/square bore adaptor and a working Carter AFB I could shoot your way for minimal. Let me know if you are interested.

 

If you get fuel coming out of the line coming from the tank, then logic says the fuel pump isnt pumping, yes?

 

I have no way to blow compressed air

 

No compressor of any sort? Even for a nail gun or a pneumatic tool?

I think harbor freight has some small compressors, about as large as a basketball, that would be able to do the job

 

Ok.....well it stands to reason that if the fuel pump will fill the glass filter from a jerry can, then you have some sort of restriction in the fuel line from the tank. How you are going to determine that is something you will need to figure out. Do you know anyone that has a small pancake air compressor you could borrow?

 

Not sure what you are trying to accomplish here. do you think his fuel line is air bound??? If so why the rubber hose. Just pressurize the tank with CA and see if it comes out the fuel line...no??

 

It's just the way I would do it. I would want to be able to see the fuel coming out of the rubber hose while blowing CA into the tank. It certainly isnt necessary, just may be easier to run 3' or 4' out to the drivers side so you can watch and see if fuel is coming out without standing on your head while trying to seal off the tank.

If he can get fuel from a Jerry Can, it stands to reason that something is restricting the fuel from the tank, or am I way off base?

 

He's getting gas to the carb and the car will start. He can't idle. He needs to keep his foot on the pedal. I don't think it's a fuel delivery problem. I think it's a carb problem. Could be his float is to low or even has a hole in it. I know he bought a new intake with another Qjet on it. not sure if he has tried that QJet yet.

 

Understood. He just made the comment "think the reason i’m not getting gas to the pump from the tank is because i don’t have enough fuel in the tank. I have the car level at normal ride height and about 4 gallons in it. I guess it could be the sending unit but its a brand new unit." on Post 1513. You are probably correct that it's not a fuel delivery from the tank issue. I assumed he had determined that he wasn't getting fuel from the tank.

 

I was getting it to run using a jerry can, still can’t get fuel from the tank. I think i threw out my back being under the car putting on the new fuel pump yesterday so i’m not going to pull the fuel line out today. I think what might have happened is when i put fuel in the tank, it brought down the crud stuck in the filler tube and so there’s probably crap in the bottom of the tank that’s getting sucked by the fuel pump and clogging the mesh sock on the sending unit. Thats the best guess i have unless something is clogging the hard main line.

Note to self, check new prebent lines for clogs before installing them...


But i also am not getting it to idle. I messed with the timing a bit and it seems like it’s definitely good where it’s at, i’m going to take the quadrajet off later and take it apart, see if i can find any internal problems. I want to modify it anyway by putting the mechanical secondary linkage on it from the other quadrajet. Hell i may even put the other carb on it, have to take a look at them here in a while and see what i’ve got!

 

Took the quadrajet that came on the new intake apart, it’s a high altitude auto tranny version which i guess isn’t a very good carb. It’s all gummed up inside and has a kind of caked dust all over inside. I’m not going to use this carb, it’ll go back on the shelf as a spare. On to the next

 

I also own a '75 Vette. All of the old Vettes of that era used QuadraJet carbs. The Corvette forum is a good source of info for info on how to repair them, troubleshoot, and tune. Here is a link to some of the best archive articles on the site.
http://www.corvettefaq.com/c3/QJetTuningPaper.doc
http://www.corvettefaq.com/c3/QJetTroubleshoot.mht
http://www.corvettefaq.com/c3/QJetTroubleshoot.mht.zip

 

I have mixed luck with Q-Jets, but once they are sorted out they can't be beat. I have a local carb shop that does mine, not cheap but I spend my $$ once and am done. Rebuilts at auto parts stores, cheaper but more miss than hits with those.

 

I could be wrong about this,and if I am please kick my butt to refresh my memory.IIRC,QJets were used on just about everything from the"Iron Duke"up to in excess of 400 CI engines.So,over the years if any swapping and changing of minor and/or major parts went on there`s no telling what a Q Jet really is.And as has been stated,the Q Jet is a sweety when it`s right.When it`s not oh what a headache it can be.
Good luck.Have fun.Be safe.
Leo