Another carb help...

[Kalums]

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?

[geezer#99]

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

[Kalums]

Originally Posted by geezer#99

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

Thank you, I will try that👍

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

[geezer#99]

Originally Posted by Kalums

Thank you, I will try that👍

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

So at 600 rpm, what was your timing?

[Kalums]

Originally Posted by geezer#99

So at 600 rpm, what was your timing?

Timing did not change, 12 dgrs advanced.

[Wrenchbender Ret]

Try it with the vacuum advance disconnected.

George

[Kalums]

Originally Posted by Wrenchbender Ret

Try it with the vacuum advance disconnected.

George

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

[leftybass209]

Originally Posted by Kalums

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

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?

[GASoline71]

Originally Posted by leftybass209

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?

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

Gary

[hugger6933]

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

[Kalums]

Originally Posted by hugger6933

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

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

[Kalums]

Originally Posted by GASoline71

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

Gary

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 😅

[Kalums]

Originally Posted by leftybass209

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?

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.

[Kalums]

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?

[Rust_never_sleeps]

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

[Kalums]

Originally Posted by Rust_never_sleeps

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

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

[Rust_never_sleeps]

Originally Posted by Kalums

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

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

[Kalums]

Originally Posted by Rust_never_sleeps

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

Stock ignition, aftermarket AcDelco HEI

[72SB]

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

[Kalums]

Originally Posted by 72SB

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

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*

[geezer#99]

Originally Posted by Kalums

So...

‘ 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 ...... *

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.

[Kalums]

Originally Posted by geezer#99

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.

Found TDC by pulling plug on #1 and manually turning crank( the balancer is dead on the little plate is off by 12 dgrs). With the VA disconnected (and plug# 1 reattached) I timed it to 8 dgrs advanced... It didn't really like it so I went to 12 dgrs... Then my fuel line from the pump to the carb started leaking AND the carb backfired.... (see photo) now I've melted the cable on the bottom of the carb (not the throttle cable connected to the gas pedal, the one on the bottom next to the return spring). Today... I'm done fiddling with it and am very glad nothing else happened. Unfortunately not my first gas fire (first in this vehicle) but it still sucks. On a good note it was running fine before the leak and subsequent fire. I think I'm going to eliminate the fuel filter by the carb and just run a line from the hard line to carb.

[72SB]

Originally Posted by Kalums

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*

No, you use the manifold vac port on carb, lower one on DS. The one slightly higher on the front, PS, is timed. The fact you advanced timing manually shows you want VA on manifold, so you get the additional timing ON TOP of your base (8-10 degrees)

Set your base back to around 8-10 without VA and the vac port on carb plugged. Then with VA connected to the manifold vac port on carb adjust idle RPM as needed

if you don't have it you can download owners manual for the 1406. and yes again it will say to use the timed vac port....its an emission thing, don't do it. It will however have all the tune and trouble shooting steps if you need them.

I am assuming your timing marks are right and the carb otherwise is in good working condition, To me, your issue was and is no VA at idle because you used the timed vac port.

[Kalums]

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

[Rust_never_sleeps]

Originally Posted by Kalums

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

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