Author Topic: Holley 1848  (Read 1990 times)

shelbydoug

  • SAAC Member
  • Hero Member
  • *
    • View Profile
Holley 1848
« on: June 23, 2020, 01:06:01 PM »
Look at the sight plugs on this carb. Why are they so different?
68 GT350 Lives Matter!

shelbydoug

  • SAAC Member
  • Hero Member
  • *
    • View Profile
Re: Holley 1848
« Reply #1 on: June 23, 2020, 03:31:49 PM »
Well what I should say is why is the secondary fuel level, judging by the sight plug location, so much lower then the primary level?

I was trying to save typing. My computer is running out of ink.
68 GT350 Lives Matter!

Drew Pojedinec

  • Sr. Member
  • ****
    • View Profile
Re: Holley 1848
« Reply #2 on: June 23, 2020, 04:35:03 PM »
They are all like that. It is normal.

Float level effects circuit timing. Also lower secondary prevents fuel spillage on hard braking.

shelbydoug

  • SAAC Member
  • Hero Member
  • *
    • View Profile
Re: Holley 1848
« Reply #3 on: June 23, 2020, 06:53:09 PM »
They are all like that. It is normal.

Float level effects circuit timing. Also lower secondary prevents fuel spillage on hard braking.

Sure but I never understood why. It's a big difference.
68 GT350 Lives Matter!

Drew Pojedinec

  • Sr. Member
  • ****
    • View Profile
Re: Holley 1848
« Reply #4 on: June 23, 2020, 08:24:18 PM »
Ok, I will answer, but it isn’t free, you have to think on it and answer it yourself, I’ll just set it up.

Look at it a different way.... why not?

Putting float level high on primary does what?
Makes fuel easier to pull from booster since it doesn’t need to lift as far.
What is the negative? Well hard acceleration and fuel will spill from booster.... but under hard acceleration the boosters are online anyway, so no biggie. Might argue that it’s beneficial.
Ok, now secondaries, why are they low?
Low fuel level makes it less likely to spill?  When would it spill? Hard braking.... the EXACT time you do not want excess fuel in the intake.

Alright, so that is technically the answer.... now for the work around!

Ok, so fuel is harder to pull from secondaries due to lower float level. Greater pressure differential is required to pull fuel. How is this dealt with?

Ok so lets look at basic calibration of a common carb an 1850.
In the primaries we have:
So we have a large idle air bleed at .067
Idle feed restriction for fuel is .026
We have a high speed air bleed at .031
So looking at high speed, what does .031 feed?  It puts emulsion air into air well. This bleed air enters high into the emulsion tube via. .026 passage. Tube has 4, .025 holes right at float level.
Std emulsion from air well to main well is 2@.028
What does this do and why?
Why does putting air in right at float level matter? What dies it accomplish?

Moving onto, the secondaries:
Idle air bleed is .028
Idle feed restriction is .031
Ok.... how is this idle circuit different than the primary?  Why?
Secondary High speed bleed is .025

How does a .031 hsab act differently than a .025?
Explain in detail and it all becomes clear.

Another work around, angle channel primary vs secondary metering block, different angle for same reason.
Now lets toss the wrench into the gears... you check float level via this plug right?
A minor angle is present in how level the carb is fore and aft.
Now mount two carbs backwards 😆

Please remember each carb was designed for a specific engine. Float requirements are different for different carbs. Thus some float bowls have different sight hole locations. All part of the overall system.
« Last Edit: June 23, 2020, 08:29:24 PM by Drew Pojedinec »

shelbydoug

  • SAAC Member
  • Hero Member
  • *
    • View Profile
Re: Holley 1848
« Reply #5 on: June 23, 2020, 09:11:36 PM »
So? I like my carbs backwards. What's wrong with that?

3300 and 3301. Came backwards on 427 Fairlanes. They like it, but now what you said about the fuel in the secondaries needing to be lower is backwards too? And it's a factory design and spec? Huh? ???

Hey! Exactly what does, "trickle out" mean anyway? Never could figure that one out exactly. Seems to be a point of conjecture around here?  ;D
« Last Edit: June 24, 2020, 06:56:12 AM by shelbydoug »
68 GT350 Lives Matter!

Drew Pojedinec

  • Sr. Member
  • ****
    • View Profile
Re: Holley 1848
« Reply #6 on: June 23, 2020, 10:36:09 PM »
I’ve done hundreds of 2x4 carbs, I don’t think I’ve ever opened the sight plug.

shelbydoug

  • SAAC Member
  • Hero Member
  • *
    • View Profile
Re: Holley 1848
« Reply #7 on: June 24, 2020, 06:41:41 AM »
How do you set the levels then?

I do know what the Holley instructions say for setting the floats dry BUT it is recommended to verify by opening the sight plugs and the fuel should "trickle" out. To me, that means the level is too high if it pours out? I'm uncomfortable with that.
« Last Edit: June 24, 2020, 07:01:34 AM by shelbydoug »
68 GT350 Lives Matter!

Drew Pojedinec

  • Sr. Member
  • ****
    • View Profile
Re: Holley 1848
« Reply #8 on: June 24, 2020, 10:23:46 AM »
You asked a question.
I explained the answer in detail which required participation....
Your participation would have answered your future questions.

Perhaps I wasted my time explaining this.
« Last Edit: June 24, 2020, 10:32:21 AM by Drew Pojedinec »

shelbydoug

  • SAAC Member
  • Hero Member
  • *
    • View Profile
Re: Holley 1848
« Reply #9 on: June 24, 2020, 12:37:42 PM »
You asked a question.
I explained the answer in detail which required participation....
Your participation would have answered your future questions.

Perhaps I wasted my time explaining this.

There isn't anything for me as I see to participate in.

You made statements and offered data to support it.

Questioning that would have seemed argumentative. That is not my intention.

I appreciate your willingness to share what you know. That is extensive.

My appologies if I have offended you. That was unintended.

The last time I got yelled at for non-participation was by an College Professor discussing a particular scene in a Shakespear play. That was over 50 years ago. I suppose some thnngs never change?  :(
68 GT350 Lives Matter!

Drew Pojedinec

  • Sr. Member
  • ****
    • View Profile
Re: Holley 1848
« Reply #10 on: June 24, 2020, 03:26:19 PM »
Installing carbs backwards and setting to the plug messes up the timing.
Having a carb without sight plugs should not be too odd, anyone here that runs Lemans bowls should be familiar with the concept.

No apologies needed, no offense taken, nor did I ever think they was an intention.

The questions will be repeated below:
(The participation is in your own mind... I provide setup for you to answer your own question)

shelbydoug

  • SAAC Member
  • Hero Member
  • *
    • View Profile
Re: Holley 1848
« Reply #11 on: June 27, 2020, 09:56:46 AM »
Installing carbs backwards and setting to the plug messes up the timing.
Having a carb without sight plugs should not be too odd, anyone here that runs Lemans bowls should be familiar with the concept.

No apologies needed, no offense taken, nor did I ever think they was an intention.

The questions will be repeated below:
(The participation is in your own mind... I provide setup for you to answer your own question)

There are some here that know me well enough to realize that don't ever let DD (they call me double D, Dirty Doug also...'cause I fight dirty...get your mind out of the gutter!  ;D) come to his own conclusions. "That just makes more problems for us!"  ::)

In fact, they are correct. Drawing my own conclusions is what got me into this mess?  It's like "Hotel California". You can check in but never check out. :o
68 GT350 Lives Matter!

TA Coupe

  • Hero Member
  • *****
    • View Profile
Re: Holley 1848
« Reply #12 on: June 29, 2020, 04:20:30 AM »
How do you set the levels then?

I do know what the Holley instructions say for setting the floats dry BUT it is recommended to verify by opening the sight plugs and the fuel should "trickle" out. To me, that means the level is too high if it pours out? I'm uncomfortable with that.

Doug,  the trickle comes into play when you open the site plugs with the engine running and the vibration and movement from the engine is what makes the fuel just slightly "trickle" out.

   Roy
If it starts it's streetable.
Overkill is just enough.

shelbydoug

  • SAAC Member
  • Hero Member
  • *
    • View Profile
Re: Holley 1848
« Reply #13 on: June 29, 2020, 07:29:07 AM »
How do you set the levels then?

I do know what the Holley instructions say for setting the floats dry BUT it is recommended to verify by opening the sight plugs and the fuel should "trickle" out. To me, that means the level is too high if it pours out? I'm uncomfortable with that.

Doug,  the trickle comes into play when you open the site plugs with the engine running and the vibration and movement from the engine is what makes the fuel just slightly "trickle" out.

   Roy

That's how I interpret it as well Roy.

Just for the heck of it, I tried the Holley method of setting the floats dry and the carbs flooded severely, so I went back to the sight plug method.

I don't like the secondaries being lower since as Drew points out, you need a certain amount of float drop to open the valves. The secondaries are so close to not opening enough normally.
« Last Edit: June 29, 2020, 09:00:20 AM by shelbydoug »
68 GT350 Lives Matter!