Off idle BOG at WOT

MonteLS_84

Apprentice
Jul 28, 2021
61
8
As the title states, I have a terrible bog when I punch the gas. Worse from a stand still but still bad at cruising speed. I've fought this battle for months, and have searched the internet plenty. Unfortunately, I don't have any local speed shops, nor do I know any knowledgeable hot-rod enthusiasts.

Note - car runs great aside from the bog.

Specs are in the attached image. For the sake of ease, I will aim to note what I have and haven't tried.

Bought car. 1984 Monte. Had a newly swapped 350 in it. Had a bog when I got it. Note - came with new fuel pump installed.

Sent the car to a shop and had a lot of work done (see attached image for specs). Upon getting the car back - still had the same bog. Note - went from the original Rochester carb to an eddy 650 at this point. Running original distributor (ECM controlled) with msd cap and coil.

Bought a brand new Eddy 650 carb - still bogging.

Swapped in a freshly rebuilt 350, bored 40 over. Used all parts from "old" motor. Note - never verified what cam was in this new engine. Mystery cam.

Replaced the distributor with a GM HEI, using MSD cap and rotor - still bogging.

Returned the 'new' carb and put the old one back on.

Tried several different timing adjustments: 8 to 15 initial...34 to 40 total.

Tried all 3 accelerator pump slots - none seemed to make much difference.

Put lighter springs in distributor. Seemed to have gotten worse, if anything.

Added fuel pressure regulator. Tried 5, 5.5, and 6 psi.

Bent accelerator pump forward and backward - little if any improvement.

Adjusted the secondary air flap in 1/4 turn increments from 0 to 5 turns (5 seemed grossly too much tension).

Replaced fuel filter.

Things I haven't done:

Messed with fuel tank - sending unit or possible filter

Why is my car bogging when I punch it?!?!

When I attempt to brake-torque...the car will stall. 😭

I'm thinking this car should be wicked...but embarrassing when you can't even get on it. What am I missing? Or did I answer my own question regarding the fuel tank??? 🤔 If it is a fuel filter or something, wouldn't it effect things other than when I am off idle and gun it?

Any thoughts appreciated!
 

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MrSony

Geezer
Nov 15, 2014
6,406
113
Des Moines, Iowa
Shot in the dark... Bad converter? I've never experienced it myself but when they go bad they can seriously lug an engine down off idle. Also, you seem to have some pretty siz able rims on there... What's your rear gear ratio?

Also, make sure your transfer slots in the carb are set to squares, idle screw turned in too far will have the blades open too far and you won't be on the idle circuit anymore. You set the carb to square, and then you adjust the timing and mixture screws to highest vacuum reading. And if you need to, back the idle DOWN. Never up from where it's square.

Holley_t-fer_slot.jpg
 
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MonteLS_84

Apprentice
Thread starter
Jul 28, 2021
61
8
Shot in the dark... Bad converter? I've never experienced it myself but when they go bad they can seriously lug an engine down off idle. Also, you seem to have some pretty siz able rims on there... What's your rear gear ratio?

Also, make sure your transfer slots in the carb are set to squares, idle screw turned in too far will have the blades open too far and you won't be on the idle circuit anymore. You set the carb to square, and then you adjust the timing and mixture screws to highest vacuum reading. And if you need to, back the idle DOWN. Never up from where it's square.

View attachment 206616
I'll take a look at the transfer slots today. As for the converter (I knew I'd leave some things out), I had the original converter when I got the car (bogged), and have a new 2200 stall now. Wheels are 20", and rear end is new...3.73 posi.

I have also played with the kickdown cable. I believe I have it set correctly (now). It did cure some other performance issues.
 

MrSony

Geezer
Nov 15, 2014
6,406
113
Des Moines, Iowa
I'll take a look at the transfer slots today. As for the converter (I knew I'd leave some things out), I had the original converter when I got the car (bogged), and have a new 2200 stall now. Wheels are 20", and rear end is new...3.73 posi.

I have also played with the kickdown cable. I believe I have it set correctly (now). It did cure some other performance issues.
If all else fails, put an afr gauge on it. See if it goes dead lean when you punch it. It might need a lot more accel shot than you'd think.
 

MonteLS_84

Apprentice
Thread starter
Jul 28, 2021
61
8
If all else fails, put an afr gauge on it. See if it goes dead lean when you punch it. It might need a lot more accel shot than you'd think.
Could you point me in the right direction of what afr gauge to use/get? Also, I hear people speak of different size accelerator pumps and squirters...but all I can seem to find are stock replacements. 🤔
 

olskool

Apprentice
Sep 26, 2021
55
18
the T/C ain't gonna make it bog. you have to have a fuel or timing issue. i would say fuel. a pin hole in the gas line will cause it to stall. back in 78 i had a 74 GTO that would run strong until you stood on it or went about 2 miles down the road, it would bog then shut off. then crank up and go again. i changed and rebuilt everything on it, nothing helped, i ended up pulling the gas tank off. it had a handful of water in it. i drained it, put in fresh gas and that solved the problem. at the time the shop i worked in had a truck come in with the same exact problem, i knew what to do. check your fuel tank, and the only way you can get water out or know is pull the tank and dump it out!
 
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MonteLS_84

Apprentice
Thread starter
Jul 28, 2021
61
8
the T/C ain't gonna make it bog. you have to have a fuel or timing issue. i would say fuel. a pin hole in the gas line will cause it to stall. back in 78 i had a 74 GTO that would run strong until you stood on it or went about 2 miles down the road, it would bog then shut off. then crank up and go again. i changed and rebuilt everything on it, nothing helped, i ended up pulling the gas tank off. it had a handful of water in it. i drained it, put in fresh gas and that solved the problem. at the time the shop i worked in had a truck come in with the same exact problem, i knew what to do. check your fuel tank, and the only way you can get water out or know is pull the tank and dump it out!
Investigating the tank, fuel filters, pump will be my next plan of attack. A couple of weeks ago I completely ran out of gas (I understand there could have stoll been some gas or water in the tank), and filled it with premium and racing fuel mix. I'd think that would've put me in a better position if there were water in the tank...but I'll still check.

Seems like it would run goofy at other times but...I'm trying all suggestions.
 
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Wageslave

Royal Smart Person
Jan 25, 2017
1,575
113
Could you point me in the right direction of what afr gauge to use/get? Also, I hear people speak of different size accelerator pumps and squirters...but all I can seem to find are stock replacements. 🤔
About any of them online that have a digital display would be good, as almost all of them use a Bosch sensor. Having one that you can switch to other fuel types or switch to display in Lambda mode is a worthy upgrade if you can spend the money on it.

Also, you might meter your pink wire going into the HEI to make sure you are getting full battery voltage to the coil. If it was below 12v, it would show itself under load before you had enough RPM's to kick the alternator in.
 
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stew86MCSS396

Not-quite-so-new-guy
Aug 1, 2022
42
18
(808)
Sent the car to a shop and had a lot of work done (see attached image for specs). Upon getting the car back - still had the same bog. Note - went from the original Rochester carb to an eddy 650 at this point. Running original distributor (ECM controlled) with msd cap and coil.

Bought a brand new Eddy 650 carb - still bogging.

Swapped in a freshly rebuilt 350, bored 40 over. Used all parts from "old" motor. Note - never verified what cam was in this new engine. Mystery cam.

Replaced the distributor with a GM HEI, using MSD cap and rotor - still bogging.

Returned the 'new' carb and put the old one back on.
I'm not quite following...are you using the CCC or not using it???
 

MonteLS_84

Apprentice
Thread starter
Jul 28, 2021
61
8
About any of them online that have a digital display would be good, as almost all of them use a Bosch sensor. Having one that you can switch to other fuel types or switch to display in Lambda mode is a worthy upgrade if you can spend the money on it.

Also, you might meter your pink wire going into the HEI to make sure you are getting full battery voltage to the coil. If it was below 12v, it would show itself under load before you had enough RPM's to kick the alternator in.
To clarify - it should read 12 volts when key is on?
 

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