Another vette bogging under load/accell and running rough
Thread Starter
Instructor
Joined: May 2005
Posts: 170
Likes: 0
From: Milton FL
Another vette bogging under load/accel and running rough
-'70 w/ 350 SB, NOM (Something post 76')
-Edelbrock Intake Manifold 2101
-Edelbrock Performer Carb 1406
She runs ok at idle (not great, but decent), but under load or acceleration she bogs for a short second and then once you get past it she is fine. It's annoying since I either accelerate very slowly and have no problems, or I have to push through the bog and then accel quite fast.
Here are a few videos of Vacuum at different locations. I found a plug wire or two that was burnt by the manifold, which would explain some of this issue (I think), but I wanted to check to see what everyone thought of my vacuum readings at different locations.
Don't mind any work from bubba you see under the hood, I'm slowly trying to fix all of his hack jobs, the car is fairly new to me
Manifold Vacuum at Idle:
Manifold Vacuum and revving the engine:
Other Vacuum locations (video show's where its connected):
And a picture of it connected to the smaller side (control side?)
I'm new to vacuum and don't know all the lingo for what these ports are called.
Thanks for the help in advance!
-Edelbrock Intake Manifold 2101
-Edelbrock Performer Carb 1406
She runs ok at idle (not great, but decent), but under load or acceleration she bogs for a short second and then once you get past it she is fine. It's annoying since I either accelerate very slowly and have no problems, or I have to push through the bog and then accel quite fast.
Here are a few videos of Vacuum at different locations. I found a plug wire or two that was burnt by the manifold, which would explain some of this issue (I think), but I wanted to check to see what everyone thought of my vacuum readings at different locations.
Don't mind any work from bubba you see under the hood, I'm slowly trying to fix all of his hack jobs, the car is fairly new to me
Manifold Vacuum at Idle:
Manifold Vacuum and revving the engine:
Other Vacuum locations (video show's where its connected):
And a picture of it connected to the smaller side (control side?)
I'm new to vacuum and don't know all the lingo for what these ports are called.
Thanks for the help in advance!
Last edited by jcbass7; Aug 24, 2011 at 06:23 PM. Reason: upload videos
Burning Brakes
Joined: May 2008
Posts: 860
Likes: 0
From: Stratford Ontario
There is a few reasons this can happen but without having it right in front of you it can be difficult to diagnose. I would start with checking if its carb related or ignition related. Is the bog like the engine shuts off for a second or two, then takes off without altering gas pedal after stepping on it? Or is it more like when you step on it and hold it there the engine bogs or missfires and stays like that for 5 secs or longer? My guess right now is that the timing and carb are not setup right for the secondaries opening. Also check that secondaries are capable of opening all the way. What other things have been changed, such as distributor or ignition things?
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
Looked at your videos, but in this video I noticed that...
http://s36.photobucket.com/albums/e1...-52-34_551.mp4
...when you opened the vacuum port on the runner to #8, the engine ran poorly; when you capped the port with your finger, it engine ran smoother. When you hooked a hose to it, it ran poorly again - it was like there was a bad leak in that hose or what it's connected to... Whatever is in that hose circuit has a large leak which admits extra air, making a cylinder run lean and missing. Fix your leaks in the vac system before doing anything else except for fixing electrical leaks in your spark plug wiring!
http://s36.photobucket.com/albums/e1...-52-34_551.mp4
...when you opened the vacuum port on the runner to #8, the engine ran poorly; when you capped the port with your finger, it engine ran smoother. When you hooked a hose to it, it ran poorly again - it was like there was a bad leak in that hose or what it's connected to... Whatever is in that hose circuit has a large leak which admits extra air, making a cylinder run lean and missing. Fix your leaks in the vac system before doing anything else except for fixing electrical leaks in your spark plug wiring!
