Edelbrock carb running super rich...

Oh, I forgot...

You can see gas puddling up in the carb here:

And there's an usual (to me at least) residue on the carb at the idle screws, PCV port, and next to the throttle...see all that here:

Ideas?

Thanks,

~jp

I haven't disassembled the carb to check the floats yet. After I sent this, I realized by doing a little reading that the vacuum was low enough to warrant first priority.

I went to the parts store and got 2 new gaskets--one for the Quadrajet manifold-to-adapter plate, and another for the adapter-to-carb. The stock bolts that came with the adapter plate to secure it to the manifold are pretty cheap--they use a phillips drive. I ran to Home Depot and got some Allen-head cap bolts and used them instead. I torqued it down pretty tight with an Allen wrench and then replaced the carb, also making sure it was good and tight.

After that I was measuring about 14.8" Hg of vacuum... What should the vacuum be?

Stock cam yes, looks like ".450'' intake and .460'' exhaust lift", and "Flat Tappet Duration @ 0.050'': 222=B0 I, 222=B0"... that was taken off the Jegs site. I ordered the motor from somewhere else, but that's the one.

Thanks,

~jp

I went to the parts store and got 2 new gaskets--one for the Quadrajet manifold-to-adapter plate, and another for the adapter-to-carb. The stock bolts that came with the adapter plate to secure it to the manifold are pretty cheap--they use a phillips drive. I ran to Home Depot and got some Allen-head cap bolts and used them instead. I torqued it down pretty tight with an Allen wrench and then replaced the carb, also making sure it was good and tight.

After that I was measuring about 14.8" Hg of vacuum... What should the vacuum be?

Stock cam yes, looks like ".450'' intake and .460'' exhaust lift", and "Flat Tappet Duration @ 0.050'': 222° I, 222°"... that was taken off the Jegs site. I ordered the motor from somewhere else, but that's the one.

Thanks,

~jp

Yeah, that's right about the cam. Supposedly the 290hp motor is the same as GM's 260hp motor, with the exception of the cam. That's what I remember the sales-dude telling me. It did come direct from GM that way though, in long-block form.

I did some serious thinking about the vacuum issue and then I remembered something... When I was in the process of installing that Edelbrock, it wouldn't clear the EGR valve--even with the adapter plate. The EGR was shot so I decided not to use it. But I didn't have a block-off plate, so I improvised (uh oh). I basically removed the upper portion (diaphram) and sunk a screw into the lower body of it to keep it in what I thought was a closed position.

So I may have just found the source of the vacuum leak. Either way, an EGR block-off plate will be installed this week. I don't like using "improvised" parts on my engine.

~jp

Try hooking up the PCV, its a large metered vacuum leak in a since. Why didn't you hook it up? Is this carb not supposed to use it but its on it? That would cause a rich condition. Then, once its hooked up re-adust everything back to normal.

With gas puddling up it is because the needles aren't closing off the fuel to the bowls. I have almost the exact same carb and had an even worse over-gassing problem. Pull the top, set the floats a hair lower than recommended. Follow the procedure for teardown that is in the book. I had to add a fuel pressure regulator on an olds 350 that I ran a Performer carb on...must have had a high pressure mech fuel pump installed before I got it or something.

DEFINATLY get a tuning kit for your carb because with the slightly hotter cam, the factory set 1406 will be to lean. Also, get an aftermarket intake from Edelbrock for your engine. If you don't, you will never get the drivability, performance, and economy out of your engine...guaranteed!

The PCV port is plugged... I have it disconnected because I was trying to eliminate any leaks and was removing anything not necessary for the engine to run.

~jp

What all does the tuning kit include? I was at Napa yesterday and the guy behind the counter pulled out the Edelbrock catalog. I was going to get the spring kit to try to experiment and lean it out. I saw the tuning kit listed--wasn't sure what it was.

If you missed it, in a previous response to Shep, I remembered my homemade EGR block-off plate from a year ago. It could possibly be a source of major leak. In any event I ordered one from an eBayer that machines them, aka custombilletworks.com....

It's supposed to ship this morning. I'll post the results.

Thanks,

~jp

Another thing, what would you recommend for the float height? 7/16" is what the manual says, but would go down to 3/8" or 5/16"?

~jp

After getting the vacuum up a little yesterday I let it run, but did not drive the truck.

This morning on the way to work the idle speed seemed quite noticeably higher than before. I take it that's a good thing...

~jp

3/8 float height.

The tuning kit includes jets for primary and secondary, primary metering rods, primary springs, tuning book, and a set of primary rod retaining springs... here is a link to the Edelbrock webpage with the kits -

It is a MUST when it comes to setting up the carb correctly!

I would also get a pair of spring loaded Off-Road Needles and seats - they helped my Blazer and Pick-Ups with drivability on and off-road.

My point was the PVC is supposed to suck air in.......more air=less fuel in the mix. Your post is titled "carb running super rich"......

I do agree here. The carb is designed for a PCV valve and does need to have one for drivability and longevity of the engine.

In a nut shell, run a new PCV valve BEFORE starting to fine tune the carb.

Ah, thanks Shades and Shoe... I see what you're getting at.

I'll reconnect it this evening.

~jp