1981 Camaro Z28

[DynoDave]

Oh yeah, if I was going through a Q-jet, I would epoxy those, issue or not. So they may very well have been done as a guard against future issues.

[MP81]

Looks like that's probably what happened, but I tested and tested and couldn't get them to leak via shop air, so I'm hoping they're all good. Too late now!

Cleaned up the main casting and throttle plate a bit:




Main casting and throttle plate reassembled:


New needle and seat installed


New float installed:


Mixture control solenoid, metering rods and power piston reinstalled:


New accelerator pump installed and TPS reinstalled:


I also reinstalled the choke housing and linkage, so I should be just about ready to install the air horn tomorrow.

[DynoDave]

Looking clean!

Throttle shaft is tight? No bushing wear?

[MP81]

Ehh...I don't think whoever rebuilt it the first time did anything with the throttle shaft or installed bushings (that I could see). There's a fair amount of end-play (maybe 1/8"), though as the blades close, they seem to center themselves when they close. I'll have to look closer when I get home and see if I see any - they don't come with bushings from the factory. It rotates plenty smoothly, though.

[farmington]

Worn throttle shaft bushings are THE main reason for funky carb problems. Hard to find vacuum leaks.

[MP81]

Yeah, in hindsight, I should have ordered a bushing kit. Oh well...

[MP81]

All back together aside from the fuel inlet:


Much cleaner:


All complete:





New versus old gasket - I'm not sure why they aren't the same:


Carb back on the car - looks a bit cleaner than it did before:


Too bad after all this work, the car idles richer than shit, and is pretty pissed off - I have succeeded in essentially making my vehicle worse.

I tried for a couple hours to see if I could mess with it (and a big thanks to JoeliusZ28 for letting my borrow his timing light with a dwell meter), but I'm done - it's dark, it still is rich, it's not making it to dyno day. No sense bothering anymore tonight.

[MP81]

Pulled the carb back out on Wednesday and got the air horn pulled off on Thursday, then I adjusted the float to 11/32" (as specified) down from the surface of the main casting and put the needle pull clip in the correct spot (not the conveniently-located, and more secure holes right there - because I guess those can cause the needle to bind and flood the carb a bit.

Pull clip - it sits pretty loose here:


Float adjusted to the proper level - a good bit lower than it was. Oops.

[DynoDave]

That will make a difference. I think I told you or Don while we were at Jakes that the last one of those I rebuilt, I built to the specs in the rebuild kit. Ran like poop, with gas leaking out everywhere. Checked a Motors manual which had a very different float level, rest it, and it purred like a kitten.

[MP81]

I'm still mostly under the impression that carburetors run on witchcraft, so I don't quite understand how a higher float level will make it run so rich/like shit, but it seems like that can tend to be a culprit, especially given I dropped mine down at least 1/4".

[MP81]

Pulled the Idle Air Bleed Valve out to check the O-rings since, for whatever reason, I didn't the first time. Upper O-ring looked mostly fine, but the lower one was a bit...flat:



Upper O-rings - new (left) vs old (right):


Lower O-rings - new (left) vs old (right) - can see how much "flatter" the old one was:

[DynoDave]

Can't hurt to try 'em, that's for sure. I've never done that.

[MP81]

Cliff Ruggles had mentioned that even there's one tiny leak in those O-rings, it can cause the idle to never be right, so it's good I replaced them. No real reason not to, especially looking at the lower O-ring.

I tightened up the screws on the throttle plate on the bottom. I don't think I had those as tight as I could have, but I do now - nothing stupid, but a healthy tight with a screwdriver. Thankfully you can only do so much with one.

Need to get this thing back on the car and out of my dining room. Perhaps today.

[MP81]

Carb's back on the car - doesn't run perfect by any means, but boy is it night and day compared to what it was like the last time. Now I think I can work with this and get it dialed in (hopefully).

[DynoDave]

Excellent! Glad those changes made a difference.