Quadrajet problem - Gawd (Long) (1 Viewer)

[fussy_cruiser]

Got up the other day and it was our first coldsnap here in CO. Got below zero overnight. Fired up the cruiser and it was running terrible, sputtering, blowing black smoke, hesitating, the works. Got it home and had my wife take me to the bus stop. That night I went and filled it with gas and put some heat in it, didn't work. Drove it up and around the neighborhood and notice my oil pressure dropping steadily. Whoa.

Next morning got up and there was fluid on the ground, checked the oil, it was about 4 inches too high on the dipstick. Checked the radiator, full. Oil smelled like gas. Dumped the oil and approx 10 - 12 quarts of fluid came out. Added new oil and filter and did a compression test on all cylinders (suspected a bad ring) all good.

Talking to a buddy's dad and he said it is the carburator, float valve or metering rod. Pulled the carb and got a rebuild kit, rebuilt the carb. Too make a long story short, didn't find anything wrong with the carb, no smoking gun. Now I'm a little shy to put the carb back on and run it.
I have:
350 SBC
Electric Fuel pump,
Block pump removed w/block off plate
The only place the fuel touches the motor is at the carb.

Question 1: Should I run this carb? or buy a reman/aftermarket unit? I can't think of anything else that could cause the problem.

Question 2: What does the pot on the right of the below picture do, is it important? and can you buy a new linkage somewhere? my linkage to this pot has been previously "modified" and does not work smoothly.

 

[grant5127]

That part you have circled is known as a.. choke break, or choke control dash pod.. by the Quad-Crowd... I would give it a good cleaning...check the fuel bowl level and give it another try.....

 

[FJFOOL]

fuel in oil

You might also check the diaphram in your fuel pump, assuming you have the stock style, not an aftermarket electric one. It would drain right into the crank-case. Good luck!

 

[ranger]

You might also check the diaphram in your fuel pump, assuming you have the stock style, not an aftermarket electric one. It would drain right into the crank-case. Good luck!

First thread, electric fuel pump.

Check your float to see if it has a hole in it, needle valve for proper seating, check float level adjustment. What PSI is you electric fuel pump putting out, should have a sticker on it with output rating? If it is to high the pressure can force fuel past the needle and seat.
THe carb in the picture has a hot air choke, is it hooked up?

 

[Gumby]

SOunds like your choke stuck or the float sank.
The part circled in the picture keeps the secondary air valve from opening at low vacuum. It has nothing to do with your problem. It would have something to do with your secondaries not working at WOT applications.

Do you have an electric, manual or heat riser choke?

Take the air cleaner off and start the truck. Does the choke pull off a little? I suspect it does or it wouldn't run at all. As it warms up, does the choke pull off?

 

[dgangle]

Do you have an electric, manual or heat riser choke?

That's an electric choke.

You measured 10-12 qts from the drained engine oil ? WTF?

You either got the thing overfilled or major diluted with gas. It's supposed to have 5-6 qts of oil depending on the oil filter/pan you have so that means you have 4-7 qts of gasoline in the oil? If this were gasoline the mixture would be so thin and reek so strongly of gasoline so bad you could definitely tell it was gas. Something doesn't sound right here. I see no way possible the oil could be THAT diluted with gas. Was it milky/white? (ie coolant)

Regarding replacing the bent rod...these are made to be bent to tweak the setup you want. Plus if you buy a new linkage you would have to bend it to get the actuation you require. One has to bend the various linkages on a Q-jet to set it up properly.

 

[theo]

I have some excellent Q-jet rebuild and tuning "literature" I pilfered from the internet. Less than 1 MB in a few Word documents. You're welcome to it.

One uncommon problem is leaking well plugs, which can allow the bowl to drain into the intake manifold. You can check this by filling the bowl with gas on the bench and watching for leaks. I agree you should check the float and choke, and the fuel pressure. Also, is the filter on the inlet housing still in place?

Q-jets that work are simple. Q-jets that need work are complicated.

 

[Gumby]

That's an electric choke.

You measured 10-12 qts from the drained engine oil ? WTF?

You either got the thing overfilled or major diluted with gas. It's supposed to have 5-6 qts of oil depending on the oil filter/pan you have so that means you have 4-7 qts of gasoline in the oil? If this were gasoline the mixture would be so thin and reek so strongly of gasoline so bad you could definitely tell it was gas. Something doesn't sound right here. I see no way possible the oil could be THAT diluted with gas. Was it milky/white? (ie coolant)

Regarding replacing the bent rod...these are made to be bent to tweak the setup you want. Plus if you buy a new linkage you would have to bend it to get the actuation you require. One has to bend the various linkages on a Q-jet to set it up properly.

The one in the picture is a heat riser choke.

I didn't assume that the one in the picture was the one on his truck.

The suggestion to check fuel pressure is a good one as well. It would be easy to have the electric pump set too high for a carb. If it was sitting and not running you could easily fill the engine up with fuel as you did.

 

[ranger]

That's an electric choke.

You measured 10-12 qts from the drained engine oil ? WTF?

You either got the thing overfilled or major diluted with gas. It's supposed to have 5-6 qts of oil depending on the oil filter/pan you have so that means you have 4-7 qts of gasoline in the oil? If this were gasoline the mixture would be so thin and reek so strongly of gasoline so bad you could definitely tell it was gas. Something doesn't sound right here. I see no way possible the oil could be THAT diluted with gas. Was it milky/white? (ie coolant)

Regarding replacing the bent rod...these are made to be bent to tweak the setup you want. Plus if you buy a new linkage you would have to bend it to get the actuation you require. One has to bend the various linkages on a Q-jet to set it up properly.

The carb pictured is not electric choke.

 

[dgangle]

I stand corrected...I looked too quickly.

 

[fussy_cruiser]

You measured 10-12 qts from the drained engine oil ? WTF?

Yea, pretty crazy. The oil was a diluted mixture of gas/oil, after approx 3 min of running I had no oil pressure. That was the original problem.

That part you have circled is known as a.. choke break, or choke control dash pod.. by the Quad-Crowd... I would give it a good cleaning...check the fuel bowl level and give it another try.....

I discovered the bad rod while rebuilding the carb. This bent rod and a bad float level were the only thing I found wrong with the carb. What happens if I remove it completely or it doesn't operate correctly? I don't want to introduce more problems.

I have some excellent Q-jet rebuild and tuning "literature" I pilfered from the internet. Less than 1 MB in a few Word documents. You're welcome to it.

One uncommon problem is leaking well plugs, which can allow the bowl to drain into the intake manifold. You can check this by filling the bowl with gas on the bench and watching for leaks. I agree you should check the float and choke, and the fuel pressure. Also, is the filter on the inlet housing still in place?

Yes, please! I reseated the lead fillings but did not epoxy like some rebuild procedures suggest.

The one in the picture is a heat riser choke.

I didn't assume that the one in the picture was the one on his truck.

The suggestion to check fuel pressure is a good one as well. It would be easy to have the electric pump set too high for a carb. If it was sitting and not running you could easily fill the engine up with fuel as you did.

No, this is not a picture of mine, this is alot cleaner. I have an electric choke, hooked it up to 12V and it appears to work fine. I suspected the pump, but it has been on the truck for the last 2 years without a problem.

Everything was working good one day and then BAM this happened the next. That is why I thought I would have an obvious flaw in the carb when I took it apart. I didn't find anything and now am a little gun shy to put the carb back on the truck. I keep thinking I could have a bad metering rod seat or ???, stuff only a reman unit would take care of.

Thanks for all the info...

 

[theo]

PM sent

 

[FineWynsFJ40]

I've got a book on Rochester Carburetors, which goes into special detail about the Q-Jet. I had a 2G on my cruiser till I swapped it for a stock one, but the book was a great resource. Bump me if interested in it. Good luck!

 

[dgangle]

the best Q-jet instructions ever

http://www.4wheelnoffroad.com/qjet.html

 

[fussy_cruiser]

Update:

Got the carb on and its running fine, don't quite have the choke adjusted properly so I have to stay on the gas in the morning until it warms up. A project for the weekend.

It looks like the dashpot's primary function is to pull the choke off at high vacuum (acceleration?) which is useless after the choke if off. It's secondary function along with the linkage is to control how fast the secondaries open under high vacuum, but it should release @ Wide Open Throttle (WOT) woot woot. Looks like most hardcore guys remove it (most don’t run a choke) and modify/increase the spring rate on the secondaries to compensate.

I removed the linkage and the truck runs/drives fine, of course, I try to drive with a light foot to keep gas mileage up.

Thanks all,