850 Holley too much?
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Joined: Feb 2017
Posts: 176
From: northwest indiana, near gary
850 Holley too much?
I have a small block olds 350 w forged flat top pistons and a big cam in my olds 98
I recently went thru the motor and swapped my edelbrock 750 and stock distributor with a Holley 850 double pumper and a msd distributor because I was getting a lot of detonation before.
I set the initial timing at 16 degrees and bumped it up a little until it pinged and then backed it back off
the car idles good but it bogs down if u smash on it or if you’re on the highway and you accelerate to pass it’ll bog down too and I can’t really adjust it to get any different results. I set the floats to what Holley said to do. Am I just bad at adjusting carbs or is this too much carb for my engine
I bought a 750 Holley w vacuum secondaries used off marketplace to try since it was really cheap. Would this be a better fit for my engine?
I recently went thru the motor and swapped my edelbrock 750 and stock distributor with a Holley 850 double pumper and a msd distributor because I was getting a lot of detonation before.
I set the initial timing at 16 degrees and bumped it up a little until it pinged and then backed it back off
the car idles good but it bogs down if u smash on it or if you’re on the highway and you accelerate to pass it’ll bog down too and I can’t really adjust it to get any different results. I set the floats to what Holley said to do. Am I just bad at adjusting carbs or is this too much carb for my engine
I bought a 750 Holley w vacuum secondaries used off marketplace to try since it was really cheap. Would this be a better fit for my engine?
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Joined: Nov 2019
Posts: 1,422
From: St. Michael, MN
The carb shouldn't be a determining factor other than not feeding it. What fuel are you running and what is the total timing of the distributor in the engine? You need a dial back timing light to get the total timing figured out. Are you running a vacuum advance on the distributor too?
Last edited by 66SportCoupe; Aug 1, 2024 at 07:24 PM.
Thread Starter
Registered User
Joined: Feb 2017
Posts: 176
From: northwest indiana, near gary
The carb shouldn't be a determining factor other than not feeding it. What fuel are you running and what is the total timing of the distributor in the engine? You need a dial back timing light to get the total timing figured out. Are you running a vacuum advance on the distributor too?
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Joined: Jan 2019
Posts: 321
From: Pittsburgh, PA
It bogs because the carb is too big, with insufficient signal/velocity to pull fuel from the boosters.
I'm guessing you have a relatively stock converter & gearing?
If you take it to 4500+ rpm then go full throttle it likely will not bog as the carb is getting into its operating airflow range.
You would be far better off with a vacuum secondary carb than a double pumper style carb on a heavy car.
The 750 should work out well.
I'm guessing you have a relatively stock converter & gearing?
If you take it to 4500+ rpm then go full throttle it likely will not bog as the carb is getting into its operating airflow range.
You would be far better off with a vacuum secondary carb than a double pumper style carb on a heavy car.
The 750 should work out well.
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Joined: Nov 2008
Posts: 8,495
From: Central Fl
You really don’t know what it’s doing.
Out of the box, that 850 is probably jetted rich.
But you have other factors as described too, converter, gear, car weight etc., not to mention power valve and accelerator pump settings.
You need to get a handle on exactly what it’s doing when it bogs, lean, rich, whatever.
And if you go back to a 750, that’s most likely jetted differently as well. You know what’s coming next, buy or borrow an air/fuel meter. It makes this process a helluva lot easier.
Out of the box, that 850 is probably jetted rich.
But you have other factors as described too, converter, gear, car weight etc., not to mention power valve and accelerator pump settings.
You need to get a handle on exactly what it’s doing when it bogs, lean, rich, whatever.
And if you go back to a 750, that’s most likely jetted differently as well. You know what’s coming next, buy or borrow an air/fuel meter. It makes this process a helluva lot easier.
Thread Starter
Registered User
Joined: Feb 2017
Posts: 176
From: northwest indiana, near gary
You really don’t know what it’s doing.
Out of the box, that 850 is probably jetted rich.
But you have other factors as described too, converter, gear, car weight etc., not to mention power valve and accelerator pump settings.
You need to get a handle on exactly what it’s doing when it bogs, lean, rich, whatever.
And if you go back to a 750, that’s most likely jetted differently as well. You know what’s coming next, buy or borrow an air/fuel meter. It makes this process a helluva lot easier.
Out of the box, that 850 is probably jetted rich.
But you have other factors as described too, converter, gear, car weight etc., not to mention power valve and accelerator pump settings.
You need to get a handle on exactly what it’s doing when it bogs, lean, rich, whatever.
And if you go back to a 750, that’s most likely jetted differently as well. You know what’s coming next, buy or borrow an air/fuel meter. It makes this process a helluva lot easier.
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