carb mounting torque?

[tab a]

I'd recently asked about a carb running rich, and leaking gas--when shut off.

Just finished putting a kit in the carb, and it still leaks--from the left side, somewhere near the throttle shaft. I'm kind of paranoid about cranking down on the 4 mounting bolts as I've read about warping the carb.

I checked the surfaces when I had it apart, and though not dead flat, it looked to be within a couple thou most spots.

Is there a suggested mounting torque? Maybe it's already too tight?

Thanks.

(On the plus side, it does seem to idle better, at least for the brief time it's been run.)

[Lee H]

Just snug. I'd say 8-10 FT#'s at most.

[jocko]

If you stuck a straight edge across the bottom and didn't see air gaps shining thru when you had it torn down, it's flat enough. Gasket will compensate for a few thou.

You mentioned leakage near throttle shaft. That's no an uncommon area - but brings up some questions.

- during the rebuild, did you re-bush the throttle shaft? Normally not part of a kit.
- so, if you did and it's leaking, I'd guess you maybe over-honed it a bit - but not likely.
- more likely, I am guessing you did not put new bushings to eliminate any slop and maybe should have.
- if it was so worn that it leaks now, and you didn't monkey with the throttle shaft - do you know if it was leaking before you rebuilt it? If yes, then I'm guessing the throttle shaft needs to be re-bushed. If it wasn't leaking before, then I'm a bit stumped.

[geezer#99]

It's not how tight you're trying to torque it down that's making it leak.
Needle and seat is leaking or float level is too high.
Look in the carb when it's running and you might see a little excess fuel.
What carb??

[tab a]

Sorry--forgot to say: Rochester 4 bbl, 72 C10.

I haven't figured out exactly where the leak is from. Before the rebuild, I suspected the gasket (which I hadn't replaced when I cleaned the carb a year or 2 ago), but now with new gaskets, I question that. SEEMS to be from pretty close to the same place. Not much of a leak, happens only after shutting the truck off, and hard to see around all the throttle stuff. (No I didn't mess with throttle bushings. )

Needle and seat are new, so that seems unlikely. Set float height at 3/8", but am not sure that's correct as I couldn't find a spec anywhere!

8-10 ft-lbs? That's almost nothing. I imagine I'm a ways past that.

Thanks.

[Lee H]

Originally Posted by tab a

Set float height at 3/8", but am not sure that's correct as I couldn't find a spec anywhere!.

All specs are in the rebuild kit.

[geezer#99]

Just because you have a new needle and seat doesn't gaurentee it's not causing the slight flooding. Could be you hung the needle clip on the float wrong. It's supposed to be hooked on and not hooked thru one of the holes. If you hook it through the hole the needle gets pulled off centre and won't seat correctly.
Here's a link to a pic. You can see the hook installed correctly. Not thru the hole on either side.
http://www.vetteprojects.com/kstyer/quadrajet_4.htm

[tab a]

I used several different how-to's from the web to be sure I rebuilt it correctly, so am confident the needle is installed correctly. Still don't know if 3/8" is correct for float height, though.

[BMERDOC]

Ok, I'm gonna go under the assumption that it leaked gas before the rebuild and now it leaks air. 8-10 ft. lbs. is a good torque. They don't have to be super tight (valve covers are 15 in. lbs.)
If it is leaking air I think Jacko is on the right path. Qjets were notorious for worn throttle shafts. Grab the throttle and wiggle it to see if there is excessive play. If it seems like it does but you still question it spray carb cleaner where the shaft goes into the base plate to see if idle changes. If it does, pull it and have the shaft rebushed.

[tab a]

<All specs are in the rebuild kit. >

Granted my eyes are getting older but I don't see any spec on the instructions. It DOES say WHERE to measure, but NOT how high the float should be. Kit was from Rock Auto.

It leaked gas before the rebuild, it leaked gas after the rebuild--both times NOT while running, but just after being shut off. I torqued it a bit more and wrote for advice. Today, it does not seem to leak.

Haven't run it for more than a few minutes, total. Will see how it does.

Thanks.