86 Burb 1406 bog down and rough idle after rebuild

[86AZBurb]

Hi folks! Looking for some opinions before I have her towed into a shop to get smoothed out. Bought her about 3 weeks ago, she ran smooth and everything seemed good. I took it to get emissions, failed on CO by a lot. I then found this forum via
https://www.gmsquarebody.com/threads/edelbrock-1406-failed-emissions.16563/page-4
and used Rich's recommendations as Val seemed to have the same issue as me. I rebuilt the carb, .92 mains .95 primaries, 7"hg springs. replaced all gaskets, new rubber on the accel pump, set floats per standard. put it back on, fired up the truck and it ran, but bogged on throttle. However it ran. The very next day, I went to try and tune it a bit better with the screws, and it would not fire up and back fired. this was last Friday, and I was leaving out of town for the weekend, so i left it till yesterday. come home, fire it up again, and the video I have is how it's running now. One other thing i discovered was the Dist hold down bolt was loose, so it may have moved. Is this a timing issue, lean issue, or rich issue. I think it's either a lean or timing(not my forte, so I may have to shop it anyways). It doesn't seem to be getting fuel on throttle. Any advice pointing me in the right direction would be welcome. I will also provide any more details I can.

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[Bextreme04]

You need to go through the whole initial setup procedure again. Do the following in this order.

1. Engine off
2. Screw in the idle mixture screws(both of them) until they lightly bottom out.
3. Unscrew them ~2 full turns(both of them)
4. Unplug vacuum hose to distributor
5. Plug port on carburetor that the hose used to plug into
6. Start truck and let it FULLY warm up
7. Set initial timing to what's on your emissions tag(or if you want max performance use a vacuum gauge to set it to max vacuum) This should be in the 4-12 BTDC range
8. LOCK DOWN THE DISTRIBUTOR HOLD DOWN!!!
9. Now you need to set the hot idle to the appropriate value.
10. I recommend using 750rpm for your adjustment point and then final lean idle RPM should get leaned down to 700RPM.
11. Follow the video below for the idle mixture setting using the above values(they recommend 20rpm drop for lean idle, but I have had good success with 50rpm.
12. Once you have set the hot idle rpm and mixture, turn off the truck and let fully cool for several hours(I usually let it sit overnight)
13. Pump the gas pedal once to the floor and slowly release
14. Crank engine until it fires.
15. Set Cold start idle to desired RPM(I usually set it on the initial startup to ~950rpm, this will usually work its way up to around 1200-1300RPM as it warms)

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[86AZBurb]

Hey! sorry, meant to reply. this helped out a lot!

Does anyone know if it's normal when adding in a new crate motor with one of these carbs, to bypass some of the vacuum lines to the canister? Someone said some of the vacuum lines i had weren't attached correctly, so I teed them into the vacuum line that goes to the PCV. The truck drove ok, but once it warmed up, the started surging at idle. So i undid the vacuum lines and it stopped surging.

 

[Bextreme04]

Hey! sorry, meant to reply. this helped out a lot!

Does anyone know if it's normal when adding in a new crate motor with one of these carbs, to bypass some of the vacuum lines to the canister? Someone said some of the vacuum lines i had weren't attached correctly, so I teed them into the vacuum line that goes to the PCV. The truck drove ok, but once it warmed up, the started surging at idle. So i undid the vacuum lines and it stopped surging.

Under NO CIRCUMSTANCES should you have anything T-d into the PCV system. You should have your manifold vacuum on the carb feeding the vacuum advance on the distributor and some other things. You should have the big manifold vacuum port on the back of the engine feeding the cruise control, HVAC, and transmission modulator(if equipped).

 

[86AZBurb]

Under NO CIRCUMSTANCES should you have anything T-d into the PCV system. You should have your manifold vacuum on the carb feeding the vacuum advance on the distributor and some other things. You should have the big manifold vacuum port on the back of the engine feeding the cruise control, HVAC, and transmission modulator(if equipped).

Seems like I saw a diagram where there was at least one thing tied in with the PCV vacuum line on the front center vacuum on the carb. the EGR?

 

[Bextreme04]

Seems like I saw a diagram where there was at least one thing tied in with the PCV vacuum line on the front center vacuum on the carb. the EGR?

No. You usually will have manifold vacuum from the carb to the TVS's and then it will split and go to the EGR and the Vacuum advance on the distributor. Then you will have the Timed port going to vapor recovery(sometimes). I dont have any emissions stuff on any of my engines anymore, but what does your vacuum routing diagram show? Either way... nothing should be T-d into the GIANT hose that is for your PCV and is always full of oil vapor.