Carb recommendations

[Monkey Uncle]

Thanks, Henry.

[Monkey Uncle]

I have the air horn off now, but I'm not seeing anything obvious that could be causing the richness and fuel seepage.  I'm posting some photos in the hope that you guys might see something I'm missing.

The float was not too high; if anything, it was a little lower than the 13/32 spec.  It was floating and does not appear to be leaking (brass float).  I didn't hear any fuel sloshing in it, and nothing dripped out of it.  The bowl looked to be about half full; not enough to close the needle.  The truck had been sitting for three or four days, so it's possible the bowl could have drained or evaporated down some.  There is some gunk in the bottom of the float bowl.

I couldn't see the needle well enough to tell whether it was seating properly when I pushed down on the float, but there was no gunk or anything in the seat that would have impeded it.  In a couple of the photos below, I hung the needle back on the float the way it was hanging when I pulled the float out.  Does that look correct?  As far as I can tell, the needle appears to be in good shape, although I could see a slight circular impression on the rubber tip where it contacted the seat.

One of the brass tubes in the air horn appears to be slightly bent near the tip (far right tube in the picture).

The rubber ring at the top of the power piston appears to have some gunk on it.

The air horn gasket partly disintegrated and left behind some debris that will need to be cleaned off of the bowl and air horn.

What am I missing?  Do you see something that might be causing the richness and seepage?

[Monkey Uncle]

More pics.

[raf2330]

The needle is in the correct position on the float. Personally, I would ditch the brass float, but there's always differing opinions on that. I'd change the needle if it shows any sign of wear at the seat since its apart. Stake ring for the power piston has seen better days, you can get a replacement for that also. They should have done it during rebuild.? You can try lowering the float level some if it is still giving you problems with seepage, as long as it doesn't go lean. I'm wondering though if you've checked fuel pressure? To much psi could cause the same problems I believe. Is APT adjusted correctly? The slight bend in the brass tube is ok as long as the diameter of tube is maintained.

[Monkey Uncle]

Thanks, Raf.  I've been wondering if I should just go ahead and replace the float and needle while I have the carb apart.

I haven't checked fuel pressure - don't have a gauge.  But I never noticed any fuel seepage prior to the carb rebuild.

I'm clueless on the APT.  Do you know of any information sources I could consult?

Thanks again.

[blazer74]

Second on the brass float and float setting not too  being to high.

You can get an sr kit from cliff which includes the float and entire acc pump assy.

The blue acc  pump cups can be hit or miss with ethanol.

If you have no surging at cruise speed leave the APT alone.

Nozzle drip at idle can cause rich, rough and or off idle stumble as well as the mentioned fuel pressure.

https://cliffshighperformance.com/Quadrajet-rebuild-kits-and-quadrajet-parts/quadrajet-rebuild-kit-sr

[Monkey Uncle]

Thanks, Blazer.  When you say nozzle drip, what are you referring to?

And another stupid question: Can I check fuel pressure without the engine running (i.e., by cranking the starter)?  Or does the engine need to be running for the pump to make full pressure?

[blazer74]

Exactly what the name implies.

With the engine running at idle, completely warmed up at operating temp with the choke completely off.

CAREFULLY look down the primary bores and look for droplets of fuel coming from the booster ring nozzles on to the throttle blades.

Nozzle drip is caused by not enough idle fuel being supplied to the idle system and the fuel is drawn thru the main system to sustain an idle.
Idles rough and exhaust can stink.

Idle mixture screws not adjusted out properly not supplying enough idle fuel and/or the throttle blades are open too much exposing the transition slot with the idle screw can cause nozzle drip.



A heavy float or high fuel pressure can cause high fuel level in the bowl causing rich idle also and fuel seepage from the top airhorn gasket and acc pump shaft.

Brass floats can get a pinhole and fill with fuel hence heavy float. That’s the reason many don’t like brass floats.
That’s not to say a nitrophyl float can’t become fuel soaked also.

Cliff has a great book on quadrajets if your interested and a quad forum with a lot of info but can be slow moving sometimes to get a response.

[blazer74]

I prefer to plumb in a gauge and monitor the pressure. Engine compartment heat and heat soak can factor in also.
Aftermarket pumps can put out too much pressure from the get go. They even advertise 7-9 psi which is to much for a quad in my opinion.

You can do a volume test and vac/suction test on the pump but I’m not familiar with the specs but that won’t help you with pressure only volume.

[Monkey Uncle]

Blazer, thanks for describing nozzle drip.  I will check for that when I get the carb back together and running.

Regarding heavy float, I read something on Cliff Ruggles' forum that suggests the brass floats are not as buoyant as the nitrophyll floats, even if they aren't leaking.  Also, I re-checked my float level, and it appears I wasn't measuring accurately the first time.  It is not adjusted low as I originally thought, but it is adjusted to the 13/32 spec, or perhaps a bit high at 7/16.  So it still shouldn't be causing the bowl to overfill, but maybe so if the brass float is not as buoyant as a nitrophyll float?  I'm finding it really difficult to measure to the nearest 32nd of an inch.

As long as I have the air horn off, I think I'm going to go ahead and replace the float, needle, and seat with quality parts from one of the Qjet suppliers.  And perhaps accelerator pump and power piston bushing as well.  No telling what was in the auto parts store kit that was put into the carb recently.

Next stupid question: The seat appears to require a 7/16 slotted screwdriver, which is a very rare animal.  Local hardware stores don't carry anything bigger than 5/16.  But I think I could order a 3/8 screwdriver on line.  In your experience, is a 3/8 big enough?

[blazer74]

I have used a wide short craftsman screwdriver before.
I also have a flat blade apex tip I use.

I’ll have to look when I get home to see the size.

The only stupid question is the one that is not asked.

I threw in a pic for a pressure gauge.

[Henry]

Hi Monkey Uncle:
From your photos I do not see anything obvious causing the seepage or rich running.

The seepage could be caused by an assembly problem such as the float insert not seated flush or the float hinge pin not being oriented correctly. Also maybe the accelerator pump stem seal is missing or shot.

When you disassembled it was there a little pump well baffle in place on the float chamber floor by the accelerator pump?

Was there a big cylindrical insert in the aneroid cavity?

Yeah, you need a special flat blade tool to get that pesky needle seat out...I think I remember having a small scrap of sheet steel that I trimmed to size with some shears and the just used a needle nose vise grip to hold it and remove the seat. You may also just take a non-prized screwdriver to a grinding wheel and make it fit the seat slot.

Setting the float height is a little bit tough without being on the bench...when you call the carb guys to buy some parts ask them if they can give or sell you one of those paper gauges for setting float height...they usually come in the gasket rebuild kit. It usually takes me 3 or 4 re-checks to make sure I have it right when laying on the engine.

If you have the time, this is a opportunity to take out the two main jets to see what their part numbers are for future reference. You can use a standard flat blade screwdriver to remove both of them. Just make a note of what numbers are written on them. They are bronze or brass so be careful you dont strip them out or strip the slot...they are soft metal and just press down hard with your screwdriver and turn carefully and dont tighten too much on install. Make sure you dont get any dirt or FOD in the jet holes and passages. You want both jets to be the same part number and for them to be a size that was recommended for your carb and application.
Regards,
Henry

[Monkey Uncle]

I found a 3/8" slotted screwdriver locally, and it worked on the seat.  Barely.  A 7/16 or 1/2 would have been better, but those are hard to find.  Once I got the seat out and could look at it up close, I could see that it had a very small piece of detritus in it, but that might have occurred when I was cleaning off bits of the air horn gasket.  There is also a ring in the bottom where the needle rests - slightly different color like the brass has been polished.  Not sure if that is wear or if it is just polished from frequent contact with the needle.

Henry - the pump well baffle appears to be in place, but there is no insert in the aneroid cavity.

I have a steel scale that is graduated in 32nds that I am using to measure float height.  The main problems are not being sure I've got the needle seated when I push down, and not having a fixed point of reference on the float to measure (the float angles down, so there's a big difference in the measurement from the end of the float vs part way up).

[blazer74]

Apex 7 flat works well inserted into a reversible screw driver.
The 3/8 is just big enough.

Lightly hold one finger on the needle and another on the hinge pin, use the other hand to measure at the toe of the float.

If you have an extra spring from the filter you can cut in half, place under the float while holding the hinge pin then measure.

Holding upside down is another way letting the weight of the float do the work while holding the hinge pin.

Don’t forget to put the metal ring back in under the seat and make sure only 1.

[Henry]

Hi Monkey Uncle:
Setting the float height is easier with that paper scale that comes with the rebuild kit...the scale has a white background and the graduations are in black...the paper scale is also a T-square and sized so it can fit in the float chamber and register on the top of the float chamber edge to make the measurement easier and more accurate. I can send you a image of where the measurement is supposed to be on the float arm.

Aneroid insert (stuffer): It appears to me the aneroid cavity has an open slot to the float bowl chamber so it would affect the volume of gas in the float bowl...my gut feel is that the insert should be there otherwise there will be excessive sloshing of gas and hence excessive movement of the float...maybe someone else on the forum can comment on this or maybe Stewart Griffin can open his M4ME carb up and see if there is a aneroid insert in it.

Regards,
Henry