Listen to this please, carb content

In reply to TheRyGuy :

Good call, but I would still advocate disconnecting vacuum advance for setting base timing wherever its source is.

It's on manifold because the distributor advance weights were set according to Lingenfelter recommendations. Lighter springs to advance sooner.

I will redo tomorrow with the vacuum disconnected.

So I didn't get a chance to work on it until last evening. On a whim I decided to try the distributor swap first I got from a friend. So I swapped the vacuum canister from my distributor to another and put everything at TDC. Started okay. Warmed up. Disconnected the vacuum advance from the carb and plugged the line. Moved the distributor until I got 12 degrees of advance at idle. Set the idle speed to about 800. Revved the engine to 3000 to see what full timing looked like when all in. FIFTY DEGREES OF ADVANCE. That's supposed to be too much, but I didn't hear it knock or ping. So I retarded the distributor and got it down to 44, with a base of 10 (vacuum advance disconnected). If I turned the distributor anymore the idle dropped. So I drove it. Best it's run since this whole thing happened. Not perfect, but no more stumble and I didn't hear any knocking or pinging. It is a low compression engine and I am running 93 octane, but still. Should I try retarding the distributor just a little more? Maybe base timing to 8 degrees? I need to put the air filter and doghouse back on and drive it so I can listen to the engine better however.

I would check if the mechanical advance has an adjustable limiter in it, or if it is adjusted with bushings. It'll likely run better with a bit more timing at idle, but you're right, 44 all in is too much. With total limited to 36ish and base at 12ish, you should be able to run 87 without worries. I had a distributor with that much mechanical advance once, after I opened it up I found that the limiter bushing had disintegrated allowing for too much mechanical advance.

back in the day i would advance idle timing to give smoothest idle and/or highest manifold vacuum, actual number be damned.  if it kicked back against the starter when hot, i would retard it in 2-degree steps until it hot-started nice.

and yeah, make sure the weights are installed properly and the bushings are OK.  38 degrees of mechanical advance is excessive, and it'll probably stutter in steady-state cruising.

So I drove it tonight when I got home. Back to square one. I feel like a broken record. So I swapped the carbs. Drove it. Real good, but I'm not saying anything until it sits over night and I'll drive it again tomorrow. The stumble and miss were gone with the borrowed carb. I'll look at the distributor. I might put mine back in to see if it gets worse. But only after it appears to run okay tomorrow. Does that make sense?

The distributor I took out has lighter weights and softer springs to bring the advance in sooner. And it didn't snap the way the replacement one did when I released the rotor, so yeah, there could be an issue there. 

I think I have overlapping and compounding issues honestly. Carb and Distributor.

Do you have the budget for an AFR gauge?  I added one to my car and I'm so glad I did. It makes tuning and troubleshooting so much easier on carbureted vehicles, and could give you some extra insight into what is going on. 
 

I mounted mine permanently (in the glove box) but this video shows how to set up a temporary one for testing. You can keep it in your toolbox between tune up sessions

I. Am. A. Moron.

I've been checking total advance with the vacuum advance hooked up. I've been creating a problem that doesn't exist.

For some reason I thought it necessary to hook it up after setting base timing. Anyway, total is at 36. It runs and drives with the borrowed carb. So I need to replace the carb. 

Thank you all for your help and advice. 

Would you...

Try rebuilding the carb a second time? Since I appear to have not solved the problem with this method is it worth going down this road again? I have no connection to anyone familiar with rebuilding these carbs to learn from.

Get a known good used carb? Yeah, I know, the internets so it's gotta be good right? Found one in Utica for $200 shipped. "Used one summer, then replaced drivetrain from 318 to 440 or something, don't need anymore."

Buy a new "EdElBrOck" online? Off brand replica I think? Throwing darts at the wind? Worse than a rebuild? Better than guessing with used?

Buy a new Edelbrock online? $$$$$$

Put on the TPI system I just got for $100 (would be even more down time as I'd have to source a TPI fuel pump and hope I can get the tank down without rust destroying lines, etc.).

Apologies if you've already gone over it, but what did you do when you rebuilt the carb? What components were replaced?

Shavarsh said:

Apologies if you've already gone over it, but what did you do when you rebuilt the carb? What components were replaced?

Only thing replaced were gaskets, needle and seats for the floats, and new filter screens. Basically what came in the Edelbrock rebuild kit.

In reply to vwcorvette (Forum Supporter) :

Was it a genuine Edelbrock kit or similarly off-brand to the carbs mentioned above?

I had a lot of really terrible results with non-original parts in some motorcycle carb rebuild kits, in particular metering stuff.

And did you have a good source for info on the rebuild process, setting float height, etc? Hoping Edelbrock would be a good source here.

I'd rebuild again long before I'd do used or off-brand. The TPI thing is really down to what you want to work on and what you want when you're done. I'm a big fan of EFI, and I'd probably prefer to wind up with that. I may or may not be stubborn enough to try to fix the carb first.

I feel like we've bounced around a little bit, but it did sound at one point like there was a passage that should be feeding the transitional port that may well have been clogged. That's what should be doing the fueling between idle and starting to get onto the main circuit. Even just doing it over with Real For Serious Carb Cleaner Soak instead of Pine Sol might be plenty to be worth redoing the process if you're not excited about starting the EFI conversion.

In reply to vwcorvette (Forum Supporter) :

https://nationalcarburetors.com/

They're local and I use them regularly.  I have stashes of carbs here if you need me to drop one off as a core.  Not sure if that will save you shipping cost or what.

Is it the kind of edelbrock carb that only wants 2.5-3psi fuel pressure? If yes, do you have a regulator and a gauge on it?

Can you explain the symptoms that you are seeing at this point? I assume they may be slightly different now that you have the distributor buttoned up. We may be able to point you to a specific part of the carb to go back over.

It was an actual Edelbrock kit.

I guess a bucket of real carb clean couldn't hurt.

4-6 psi. I have an adjustable reg on it cause the tbi fuel pump puts out about 12. It's currently at 5ish.

I will investigate that link.

Oh man, recounting the issues. Well...sit down.

I drove the van during a bad rainstorm (we've had a few here in Vermont) and it started missing and losing power. Pulling the cap it was just covered in heavy moisture/totally wet inside.

I grabbed a replacement cap, rotor, coil, and ignition module cause it has been a long time since a good tune.

I thought all was good, but when heading out the next day I got onto the highway and while trying to accelerate up to speed it started to miss/lose power. I nursed it off the highway where it died. The more I drove it the worse it got.

Towed it home. Pulled the plugs. Fouled. Replaced with new AC Delco plugs.

Still running poorly. It would move out easily on light load but with any request for power (incline or acceleration) it would miss and die out. Start right back up. Towed it home AGAIN.

Tried another distributor. Caused a bunch of issues poorly setting the timing. Repeat, I. Am. A. Moron!

Anyway. Got the ignition straightened out but still had drivability issues. Any tip in beyond part throttle would cause stumbling and loss of power.

A friend loaned me his good carb. Installed that. No more issue.

Up to date.

vwcorvette (Forum Supporter) said:

4-6 psi. I have an adjustable reg on it cause the tbi fuel pump puts out about 12. It's currently at 5ish.

As the Perturbed Corvair pointed out the Edelbrock wants 3 psi max. 5 psi is likely to cause flooding.

L5wolvesf said:

vwcorvette (Forum Supporter) said:

4-6 psi. I have an adjustable reg on it cause the tbi fuel pump puts out about 12. It's currently at 5ish.

As the Perturbed Corvair pointed out the Edelbrock wants 3 psi max. 5 psi is likely to cause flooding.

Everything I've read says 5.5 not to exceed 6, including the Edelbrock website.