Another carb help...
 

So... I've got an Edelbrock 1406 that replaced the original QuadraJet ( I didn't do it, it came this way) I rebuilt the 1406...runs amazing, but I get significant rpm drop when I put it in gear (stalling) . Cold or hot it doesn't matter. What gives? I've done a complete tune up, plugs AcDelco R45ts (gapped to 45) new MSD 8mm wires(I know that means insulation) the HEI is a Delco and it is putting out about 15k volts on each lead and wire at the plug(zapped myself a few times testing... Ouch) timing is set to 12 dgrs advanced @ 800 rpm idle. Choke is electric and appears to be working/functional (choke flap is opening slowly as it warms)Vacuum gauge shows good vacuum hot or cold. My vacuum advance is connected to the vacuum port on the passenger side of the carb(swapping to driver's side port only increases in park idle speed) . I've sprayed carb cleaner on ever crack crevice and hose, I can't find a leak if there is one. Everything is set up per the Edelbrock set-up guide and everything I can find from the Google overlords. What am I missing?

Re: Another carb help...
 

Turn your idle down to 600 rpm.
Then check your timing.
At 800 rpm the mechanical timing might be kicking in,

Re: Another carb help...
 

Thank you, I will try that👍

Tried this morning... No go, still does the same thing.

Re: Another carb help...
 

Try it with the vacuum advance disconnected.

George

Re: Another carb help...
 

So at 600 rpm, what was your timing?

Re: Another carb help...
 

Did it have these symptoms before you rebuilt the Edelbrock?

is it the original cast iron manifold with a carb adapter, or is it a square bore intake manifold?

Where do you have the idle mixture screws set, and do they actually change the vacuum signal/idle speed when you run them in/out?

Re: Another carb help...
 

Those spread bore to square bore adapters are notorious for air/vacuum leaks.

Gary

Re: Another carb help...
 

Spray some carb cleaner around the base and listen for RPM changes when you hit the vac leak you have it will rev up. Jim

Re: Another carb help...
 

Timing did not change, 12 dgrs advanced.

Re: Another carb help...
 

Rpm goes up about 40-50rpm but other than that no change.

Re: Another carb help...
 

Original manifold with adapter, mixture screws set 1.5 turns "open" after screwing all the way in (snug, not torqued). Yes it starts to lean out if I turn the screws in about 1 full turn and it also starts to run rich/bog if I turn the mixture screws out more than 4 full turns. Vacuum does change significantly either way.

Re: Another carb help...
 

I've soaked the manifold/carb/ and anywhere I even think there could be a vacuum connection. No rpm changes... 😩

Re: Another carb help...
 

Not gonna lie, I'm leaning that direction... I just didn't want to spend the $$$ on an entire manifold, my wallet already looks as dry as the desert I live in 😅

Re: Another carb help...
 

I understand that the Edelbrock is a much easier carb to tune/rebuild... But I do have the original Quadrajet... Would it be worth my effort to rebuild? Assuming it is rebuildable...
Do they make an electronic choke "upgrade" for the Quadrajet?

Re: Another carb help...
 

I'm thinking you wouldn't get the idle speed down to 600 if there was a vac leak

Re: Another carb help...
 

you really want VA using manifold port, not the timed one. You may have to back down "initial", aka base, timing a few degrees as VA will add some at idle likely. You want 20-24 degrees with VA connected so if VA provides 12 degrees advance, set base at 8.

Fairly classic symptom of bog. die, without VA on manifold vac when put in gear (automatic) if that is what is happening. Eddy carbs are dead simple to tune, basically a Carter AFB

Timed port vac was a failed emission thing. Yeah I know the carb manual says use it, they basically have to. Just plg the timed port and use manifold vac for VA.

Now adjusting VA to come in and how much is a different discussion but the 411 above should resolve the stall issue when put in gear.

Vac leaks typically increase RPM so does not sound like that is happening

Re: Another carb help...
 

Don't get me wrong... It was struggling at 550rpm...and ran rough at 600...but it stayed running🤷

Re: Another carb help...
 

So... I should disconnect from the carb and connect the VA to the manifold?

I went back and read you post again... And literally walked out to the truck to try this... When I have the VA plugged into the carb (timed port?) it runs rough (like I need new motor mounts... Which I have in the garage) at 12 dgrs advanced (manually set by me using a digital timing light) but if I turn my distributor ever so slightly til it is about 20 dgrs advanced it speeds up my rpms AND runs smoother. I can then turn down my idle to 800 rpm and it only drops to 650-675 when I put it in gear, still a drop but no stalling ...... My light bulb just came on... Was I manually retarding my timing? Too much?? Was I the "malfunction" *face palm*

Re: Another carb help...
 

When setting "initial timing" should my VA be connected or disconnected?

Re: Another carb help...
 

Sure, but IMLE, with even a tiny vacuum leak, the idle speed just won't drop below 1200, maybe 1k because it's still sucking air through the leak when the plates are closed.

What kind o' ignition are you running, btw

Re: Another carb help...
 

Initial timing should be with VA disconnected(and that hose plugged)

Re: Another carb help...
 

Stock ignition, aftermarket AcDelco HEI

Re: Another carb help...
 

I.... Am an idiot... Or just nieve... It is currently too late for me to futz with this anymore tonight (kids are sleeping and V-8 currently with straight pipes AIN'T quiet) thank you for the assistance, I'm pretty sure you guys figured it out and I just need to put in the work. I will report back tomorrow. Thanks again.

Re: Another carb help...
 

Here's my 2c. If you have vacuum assisted brakes, try it with that port (and any other vac. ports) on the carb plugged.If that's not it, you need to go back through that Edelbrock and check the idle circuit very carefully. Also, it would help if you answered Leftybass209's question; How did it run before you went through the carb? -BA

Re: Another carb help...
 

That there tells you one thing!
Your timing marks aren’t accurate.
Either the mark on the balancer is wrong or the timing tab is wrong or a combination of both.
You need to find true top dead centre on #1 cylinder to see where your timing tab/balancer marks are at.