I have a 1971 w/350 auto- when I got the car I see someone put a sort of large inline fuel filter about 4 inches up from fuel pump thus rubber hose on each side of it then back to steel line to carb. Isn't it suppose to be steel line directly from fuel pump to carb (no rubber) then isn't their suppose to be a filter inside inlet to carb ( quadrajet)? I got a small filter that suppose to be in there but noticed some used cones..some had spring..and according to parts counter mine just uses paper filter with no spring and no inline filter.. please help me figure what I'm suppose to have? I read that years make a differance so as stated mine is a 1971

 

Lars is the perfect person to ask this of. I know the filters had a spring behind them and a one way valve built into them, but Lars would know which years had what.

 

You are correct: Your 1971 should have a 1-piece steel fuel line from the pump to the carb. Good reproductions are available from most of the major Vette parts suppliers, and I strongly recommend you get one to eliminate the rubber line with the in-line filter. The carb should have an in-carb filter (paper element). This in-carb filter is actually very good, and is available with a checkvalve to reduce the tendency of the float bowl to empty itself overnight.

The parts look like this in the as-installed sequence. All Q-Jets have the same setup (although the later carbs use a 2" long filter). All Q-Jets require the use of the spring behind the filter to push the filter into the inlet nut and seal it so the fuel goes through the filter (and not around it):


Make sure you use a flarenut wrench on the 5/8" hex flarenut that screws into the carb inlet fitting, and use a 1" backup wrench on the inlet fitting. Lubricate all threads on the inlet fitting and on the flarenut with assembly lube prior to assembly, and be careful how much torque you put on the inlet fitting so you don't tear the threads out of the float bowl.

NAPA/Echlin part number for your filter is 3051. Sells for about $4.

Lars

 

Thank you all.. Do you sell products Lars? I need everything in pic. I bought a filter at local store but low grade and spring was missing in carb. I have nut but could use another if available.

 

Not trying to hijack your thread but, Lars do all the filters have check valves? I have had an issue with my 1969 L46 with a quadrajet not wanting to start after sitting for few days as if it is starved of fuel. Coudl it be getting though the filter? I will post an new thread if its complicated to not confuse Stingraygene's post. Thanks ike

 

I don't sell parts. All parts you need are available from various aftermarket sources:
As noted the filter is available from NAPA under part number 3051.
The spring is available from NAPA under part number NOE 7321078 or from Carbs Unlimited under part number CUFSS
The fuel inlet fitting is available from Carbs Unlimited under part number CUD201

No, all filters do not have checkvalves. The part number I have referenced above in my previous 2 posts, 3051, is the NAPA part number for their "Gold" line premium filter with checkvalve. If you need the 2" long filter for the 1975+ Q-Jet, the part number is 3052. There are other problems that can cause the float bowl to run dry overnight, as outlined in my papers. If your car is hard to start "after several days," you have issue #7 - normal issue with modern fuel. Extract pasted here:

Technical Explanation: My Car Is Hard to Start – My Carb Must be Leaking all the Fuel Overnight!

One of the most common complaints on a Q-Jet carb is that the car is hard to start after sitting overnight or for a few days: The engine must be cranked excessively and will finally start after pumping the gas pedal repeatedly. The common diagnosis is that “The carb well plugs are leaking – you need to epoxy the plugs.” Actually, there are several issues that can cause this symptom, and the plugs are seldom to blame – some of these things can be fixed, and others cannot, but there is no one single cause for this problem:

1. The most common cause of Q-Jet start problems, if it occurs after the car has been sitting overnight or longer, is that the fuel standing in the fuel line between the pump and the carb is draining back through the fuel pump checkvalve due to a slight leak in the pump's internal checkvalve. Since the Q-Jet's needle and seat is in the bottom of the float bowl, the fuel draining back through the fuel pump will actually siphon fuel out of the carb's float bowl. To fix this, you need to replace the pump, but not all new pumps have checkvalves that seal completely, thus the problem can persist. You can check for a leaky checkvalve in your fuel pump by running the engine for a minute and then shutting it off. Wait about 5 minutes and then loosen the fuel line at the carb. If the checkvalve is good, there will be fuel pressure at the carb when you disconnect, and gasoline will spray out forcefully when you loosen the fuel line. If gas does not spray out and you only get a slight dribble of fuel, your checkvalve is allowing drainback.

If this is the case, you can first install a checkvalve inlet filter, part number 3052 from NAPA (for the “long” filter, or 3051 for the “short” filter) and see if that cures the problem. If not, you can remove the clip from your needle so that it will drop down into the seat after engine shutdown to seal off the seat from the siphon action.

2. If this does not cure it, you may have a leaky float bowl well plug (either on the primary or secondary side). Before doing any well plug repairs, I strongly recommend that you verify this problem first: If you remove the carb from the engine and set it up on some tall sockets on your workbench, you can fill the float bowl with fuel and easily see if the well plugs are dripping. Leaky well plugs will be readily and immediately visible. It is seldom that a post-’70 Q-Jet will leak from the well plugs. To fix leaky primary well plugs, drill and tap the well plug area for #10-32 screws. Install 10-32 x ¼” Flat Head Socket Cap Screws coated with JBWeld epoxy into the threaded holes – this is the only permanent repair to the leaky plugs. If the leak is on the secondary side, you can install the thick secondary well gasket that is provided in almost all NAPA/Echlin rebuild kits.

3. Many Q-Jets came from the factory with porous castings, resulting in fuel leaks right through the exterior and internal walls of the carb. If this is the case, you need to replace the carb. I have seen many of these, and you can often find the problem by, again, setting the carb up on your workbench, filling the bowl, and observing where the drips are coming from.

4. A bad accel pump will cause hard starting (since no fuel will discharge when giving it the “pump” as described in step 1), and bad accel pumps are extremely common with today’s ethanol-additive fuels. After the engine has been running, shut it off, look down the carb, and flick the throttle lever slightly. Verify that you have an immediate pump shot in both primary venturies. The accel pump will often lock up in the pump bore due to the ethanol in the fuel, resulting in an inoperable accel pump – the lever and pump rod will go up and down, but the rubber “cup” can be seized in the pump bore. This will make the car very difficult to cold-start, but can produce satisfactory performance once the engine has started.

5. Verify correct operation and setting of the choke. An inoperable choke will make the car very difficult to start. See the Choke Setup section of this paper.

6. Operator error. Many new musclecar owners are not familiar with the correct operation of carbureted engines, and believe that the engine should cold-start without touching the gas pedal. A carbureted engine requires a fuel shot from the accelerator pump in order to start cold, so the gas pedal must be pumped a few times in order to “set” the choke and to squirt fuel into the intake manifold. Be sure you are using the correct cold-start technique of pumping the gas pedal two to four times before cranking the engine on a cold start.

7. Finally, there is the issue of modern fuel. If you have stopped the drain-back and siphon problem and have verified that you have no leaks, you likely have a problem with the high vapor pressure of modern fuels in the Q-Jet's vented float bowl. The fuel currently available has significantly higher vapor pressure than the fuels that these carbs were designed for. Since the Q-Jet float bowls are vented, the modern fuels will evaporate out the vent tube, dropping the float bowl level just enough so that the accel pump well will not fill with fuel (the Q-Jet accel pump does not get its fuel from the bottom of the float bowl: the bowl must be nearly full for the pump to function). If you have ethanol-additives and high vapor pressure fuel in your area, causing evaporation loss out the carb’s vent, there is no fix to the problem.


Lars

 

Lars sorry for the delay in my response!!! As alway a excellent diagnostic answer. I wish I had a one hundredth of your knowledge. I will try some of your diagnostic testing. Some of them are easy for me and some not so.
I have only delved into a carburetor once and it did not turn out so well. But i was young and not to smart and lost some springs. Now that I'm wiser I may take another shot it it but i will leave that for another day and post. Thanks Again Ike.