Qjet Float Height Looks Wrong

[Bonnewagon]

Those screws should be the "Double D" type. They make a 1/4" drive socket that fits them. In a pinch a secondary hanger can have it's end ground down and the shaft will fit the DD. They used those carbs on 350's too. Some had an electric hot-soak lean-out solenoid in the spot where the CCC carbs used the mixture solenoid. As Steve said, if you can't find the exact float setting 1/4" works most of the time.

 

[Bonnewagon]

Somehow I convinced myself I was doing it right last night.

Sounds like one of those times when you waste five hours banging your head against the wall and once you walk away- the next day you solve it in five minutes.

 

[Supercharged111]

Sounds like one of those times when you waste five hours banging your head against the wall and once you walk away- the next day you solve it in five minutes.

Story of my life.

 

[Supercharged111]

So I do have double D screws, got the driver for them last year when the didn't respond to adjustment of them at all. That's when the carb got scattered and I got to reading up on these things. I've slept since then, so I'll have to reread. Here's what I got for float height measured at the real back of the float.

This is set at 12/32", right near the .420" spec I pulled from here.

This is from a how to tune qjets article by tunedbylars.com. Unless 800cfm RV carbs are an exception?

 

[Bonnewagon]

I can't find the exact float level for that truck carb. But almost every '85 I found ran 11/32" or .343" which is very close to what you are using but a bit higher. But that float arm needs to be bent more. Don't be bashful- they can take it. Another trick for when they drive me crazy is to measure from the gasket surface to the inside near where the float toe is. Make a line with a magic marker. Then go by that instead of trying to hold it all together while trying not to drop the little paper ruler that comes in the rebuild kit. .

 

[Bonnewagon]

I found this: a 1985 454 carb float is 3/8" or .375"- not far from what you are using. https://www.carburetor-parts.com/assets/instructionsheets/k4249.pdf Wowsers! RockAuto wants $435 for a rebuilt.

AUTOLINE C9676 {#17085004, 17085212, R4M4MEF} Rochester 4 Barrel; Reman. Info w/Federal Emissions Emission; R4-M4MEF; w/Electric Choke

$435.79

core $100.00

total $535.79

 

[Supercharged111]

I found this: a 1985 454 carb float is 3/8" or .375"- not far from what you are using. https://www.carburetor-parts.com/assets/instructionsheets/k4249.pdf Wowsers! RockAuto wants $435 for a rebuilt.

AUTOLINE C9676 {#17085004, 17085212, R4M4MEF} Rochester 4 Barrel; Reman. Info w/Federal Emissions Emission; R4-M4MEF; w/Electric Choke

$435.79

core $100.00

total $535.79

I just found the exact same thing in a pdf provided by quadrajetparts.com so gonna roll it back to that. Now for the next question: I'm trying to set the adjustment screw to achieve this with the metering rods.

But my rods look like this.

The fat part slides right through the jet. Is this normal or do I need drastically smaller rods? The car has always been pig rich but my bringing it to CO has only made that worse.

 

[Bonnewagon]

adjustment screw

Do you mean the APT screw? If so that "should" have been screwed down to bottom, the number of turns written down, then put back to the same setting. If that is not possible then I find four turns is "about right". The metering rods are just a restriction that produces the mixture for idle, off idle, and part throttle. Gas flows around them. All the tips are the same size, Once fully up then the secondaries take over. It is the upper part that sits in the jets and determines the mixture. That is a lean tapered rod. What size jets are they and what is the number of the rods?

 

[Supercharged111]

Do you mean the APT screw? If so that "should" have been screwed down to bottom, the number of turns written down, then put back to the same setting. If that is not possible then I find four turns is "about right". The metering rods are just a restriction that produces the mixture for idle, off idle, and part throttle. Gas flows around them. All the tips are the same size, Once fully up then the secondaries take over. It is the upper part that sits in the jets and determines the mixture. That is a lean tapered rod. What size jets are they and what is the number of the rods?

Yeah, I haven't touched it, but also don't trust where it was set at to begin with. Jets were 75 but after some math, a 20% reduction for altitude came in at 4 jet sizes lower so 71 is what rides in there now. I also nabbed some 69 but need to hook up the wideband before I go that far. Rods are 58S.

 

[Bonnewagon]

75 is a big jet. My stock Pontiac 455 had that size. 71, 72, is often used for a stock Pontiac 400. 58 rods are very lean. 400's and 455's used rods in the 40's range. I used to have a formula for the rod to jet size ratio but that was only for stock motor carbs. A cam change tossed that right out. What engine is this on and what does it have?