Where to Measure Float Level

[Bill75]

I'm rebuilding a 79 Q-Jet and I have some conflicting information on where exactly to take the measurement for the float level.

Doug Roe's book clearly shows measuring pretty close to the middle of the top, I've run across some pictures from Chevy High Performance that show the same thing. I've also read procedures that say to measure it at the rear edge (the edge closest to the needle valve), the same place Lars recommends.

This carb calls for a .420 float height.............with that setup and measuring at the rear, it puts the float at a considerable angle and sure doesn't provide a whole lot of travel before the needle closes. To my untrained eye that relates to a pretty low gas volume in the bowel, it just doesn't look right to me. Because of the float angle, measuring in the middle would result in a higher bowel level by maybe .050 or so.

Anyone have any real world experiences with this?

Bill

 

[6880 Mike]

I would go with Mr. Roe's recommendation.

 

[RodsnRides]

Agreed

I would go with Mr. Roe's recommendation.

I have to agree with Mike. I usually measure in from the "toe" (closest to carb center). Can't recall just now but I think it's 3/8" - 7/16". I also hold everything with my thumb and forefinger and turn the bowl upside down and see where the float "drops" to and give a good visual to see that the float is not to high/not too low, but about center.

Did you epoxy your main wells/primarys/front inlet plug, too? Highly suggested...

Rick
:gap

 

[Bill75]

Did you epoxy your main wells/primarys/front inlet plug, too? Highly suggested...Rick:gap

Yes I did epoxy them, I have one on the car now that leaks. I'll be glad to get it off and get this one "tweeked" and get rid of the gas smell.

I'm glad you guys agree on the more central location, it looks too darn low using the other method.

Thanks for the replies and the tip.

Bill

 

[TimAT]

There used to be a line cast(?) into the float. I'm thinking that was where the measurment was made from. Been a long time so I could be incorrect..

 

[GerryLP]

Bill,

It should be through the vent slot or hole closest to to air cleaner stud. To check, you place the tool on the float while the engine is idling (don't press down or it will food the engine).

View attachment 14429

 

[MikeMc71]

Is there a certain brand or type of epoxy you should use?

 

[Bill75]

There used to be a line cast(?) into the float. I'm thinking that was where the measurment was made from. Been a long time so I could be incorrect..

Tim....you are correct, there is a line about 3/16 in in from the toe molded into the float!! Thanks!!

Jerry.......thanks for the picture, Figure 2b shows the line that Tim mentiones. I've never seen those gages to measure one while on the car, I'll have to ask at the store some time. Thanks for posting the picture!

Mike......I used JB Weld on mine, someone else on the forum recommended it to me last year. Seems to be gasoline proof, easy to mix, doesn't run. Cures overnight. Bought it at the hardware store.

Bill

 

[MikeMc71]

Thanks!!

I Found out today (from a local speed shop), JB Weld has another product called "Waterweld", its a putty you can use under just about any liquid. They recomend it for the Q-Jet repair, because you don't really have to clean the gas off the parts. I cleaned mine off anyway, just to make sure.