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Hi Folks - due to economic conditions I am forced to rebuild my own carb. Haven't down this in 20+ years.
Trying to figure out which mettering rods, metering rod hanger and primary metering jet to use. The carb I have on there now is from a 1971 W31 motor.
I have a 1970 455/AT. The cam has always been in question. I did not get a cam card from the engine builder - all he sent me was: 308 duration and 472 lift.
That sounds like a W-31 cam...quite a bit of overlap so the idle quality will be your biggest issue. True 4-speed W-31 Q-jets came with no Primary power piston nor rods and 2-BBL jets. You can get by with a .072 Pri jet and .047 Pri rods with the SOFTEST power piston spring offered. May need more jet if using Headers.
Ugg - still having major issues. The screw driver trick did not work, so I rebuilt it on Saturday. Same issue. It ran well for a few days then died again. It seems to blow fuel out of the accelerator pump.
I am wondering, is it possible the fuel pump is pumping too much gas into the carb. I had tried a Holley 3110 originally and that ran like junk. Then the carb from my original 350 motor and that runs - but barely and now this carb.
If you’re blowing fuel out of the top of the carb the float is likely bad (fuel saturation is common with today’s gas even for a new float) or its not adjusted right. With the bowl inverted the float should be slightly above horizontal not below.
If you’re going by the original level setting you will need to alter it a little due to the crap gas we have today. You want a touch less gas in the float bowl. So you want the float to stop the supply earlier than the original spec by as little as 1/16”- 3/32 or as much as to 1/8” lower than the factory setting. You may need to play around a little to find out where it likes to “live.” Keep the float drop spec. where the spec calls for it to be.Also be sure you have a high quality rebuild kit not a cheepo. The accelerator cup needs to be the latest material to live in todays gas.
The needle and seat could be bad or the needle isn’t in the right spot on the float?
With the car idling look down the carbs primary venturis. Do you see fuel bubbling out of the two small vertical slots just above the air/fuel needle bore holes? That’s an indication of fuel over-run due to a high float setting. The car will idle rich and rough too.
Does the fuel pump have more than 7psi? If so it’s blowing fuel past the seat due to excessive psi.
I have seen a tear in the accelerator pump and a crack in the plastic pump cup holder cause fuel to spit up from the accelerator pump shaft but only when actuating the accelerator and it was only a small amount. Does your problem occur while it’s sitting there idling or when you actuate the throttle?
Are all the check ***** present and accounted for? Did you give each check ball a light tap with a punch/hammer to insure the ball is mated to its seat?
Short of all this something’s cracked or missing in the assembly???
That link does indicate 8psi. Thats over the rated spec for a Qjet.
Hmm. Here is what I did so far. I put the factory fuel pump back on. Then I took an Edelbrock 1406 that was working perfectly off my sons Camaro.
I figure I'll run this for a few days and see what happens.
My fuel pressure gauge is plumbed to my Holley and I don't have the hardware to plumb it to the quadrajet.
I can pull the quadrajet open this weekend and check the float levels. I know the needle and seats were good, but I don't know how to set the float levels. Guess its time to learn.
Google and or YouTube it. Its real easy. You will need a fine mechanics rule with 1/64th or 1/32" increments. I usually set the drop so it doesn't touch the bowl floor. For the level, as an example, on a 7028251, I start out at 1/4" per spec and usually end up at 17/64 or 9/32". Sometimes even lower if its a hot runner that has sooty pipes and rough hot soak idle. This is on a street driven stock engine with 93-94 Octane.
The biggest deal with the level is to get it low enough so when the carb is heat soaked and the fuels hot its not spilling over in to the "off idle" slots above the throttle valves (as I described in my last post). But high enough so not to fuel starve (lean out) it at high RPMs. So its a balance.
I had a problem once with a Q-jet that may apply here; the little spring clip that connects to the needle, and hangs on the float, somehow got bent, and wouldn't stay in the indention on the float.
Two needle nose pliers straightened it out, and the carb was fine after that.
Hey Guys - I took a few pics, I hope I pasted the links ok.
Curious - I originally thought the piece was a fuel filter, but wondering if it is some type of restrictor. I took it out when I installed the carb cause I use an inline filter.
One is the spring on the float. I noticed someone had mentioned how the spring was attached to the float. The other is of the needle/floats I have available, Both are new.
The first picture shows the original sintered bronze fuel filter.
The second picture shows the float-needle hanger "spring" improperly attached to the float arm. As Bill said above,
Originally Posted by BILL DEMMER
do not put the needle pull clip through any of the holes in the float arm.
You can see that the clip goes right through one of the holes.
It needs to just clip over the edge of the float arm - if it's installed like that, it will definitely cause flooding like you experienced.
Never let anyone else fix anything of yours, and always check any parts that anyone else "rebuilt" or "repaired," as they will probably be screwed up.
The needle & "windowed" seat on the right is correct. I don't see the tip on the left needle? The pull clip attaches to the needle, as seen, not the float. The pull clip just is there to guide the needle into and out of the seat. So it just sits on the float. If you had the left hand needle installed that's missing its tip that's where the over flow of gas came from. What you originally thought was a filter, is a filter. Its a sintered-brass (Morrraine) filter and is not recommend for higher performance. It can be restrictive and will clog quickly especially drawing fuel from an older tank. You can purchase regular style paper filter to go in place of the brass. You can use this with the inline you already installed though Id recommend only using the OEM filter at the carb. Be sure to pay attention to proper filter direction & relief spring location when installing it. Be very careful threading the filter housing into the carb. It will cross thread quickly creating the dreaded OH Sh*T I just stripped my carb response. Clean the threads thoroughly on the air horn and housing with a brass brush. Use a dab of anti-seize or petroleum jelly on the threads, never use Teflon. Do not over torque upon installation!
Well, its probably too early in the year to win the moron of the year award, but I'm in the running.
Seems like the spring that goes in the power piston assembly, I put in a place to the right that had a ball bearing and screw assembly to the right of the float.
I think I'll go with the needle and seat assembly to the left. It seems the float height is about 1/8 inch with this one and I won't have to mess with it. It really doesn't have to be perfect because I want to rebuild my original carb with the recommendations made here. So the idea is just to get the car running. If you all think I'm crazy, please don't hesitate to share!! LOL
I believe I am doing something wrong assembling my accelerator pump.
This is the assembly and how I am placing it into the carb, but I see no way to seal the top of the piston from the top plate of the carb... am I missing a part, or am I set this up incorrectly?
A lot of good info in this thread. Especially drolds' float level recommendations. I'm subscribing, lol. I know the needle hanger always threw me for a loop, too. It' just hangs there? That can't be right. But it is. The last "rebuilt" carb I bought was a mess. And yeah, it had the needle hanger in one of the holes and the float was set way too high.
Also, I've never tried using jelly on the housing threads. I'm going to do that on the Q-jet rebuild for my 455.
Lastly, do the rebuild kits normally come with a new filter housing gasket o-ring? I think that's why a lot of folks over-tighten and end up stripping the threads. I bought a pack of ten for something like $5 on eBay.
Last edited by Macadoo; December 13th, 2017 at 10:44 AM.
Believe me Im one for taking a breather every now and then and my interest is off and on, but I just realized it was like 5 years ago when this thread was started. If its taken this long I probably would have bit the bullet and paid someone? Have you been able to use the car?
I would have forgot everything if I took it apart 5yrs ago and then try to put it back together today.
Lol - yes - the car has been running, although I really dont drive it too much.
But yes - sometime though out this period I sent my original carb off to Cliff to rebuild. The only thing I wasn't prepared for was that it came back in a zillion pieces and I had to assemble it ! But that being said, it was fun to play with it. Cliff said I could send it back and he would assemble but I love puzzles. But it did always leak a little from the accelerator pump so I decided to take it off this past week and mess with it.
I will say - I was never able to get this car to run correctly before. I tried several combinations of a Qjet, Holley and Edelbrock and what ever Cliff did was like magic. I can not say how impressed I am with him.
I did finally yesterday get that leak fixed - but I most likely will pull it apart again soon and try playing with the float level - not sure I am happy with it.
December 18th, 2012, 06:08 AM
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