Sounds good. Meantime, happy holidays everyone and merry Christmas.
Fine Tuning a 360 Magnum with a Brawler "Double Pumper"
- Thread starter jmanhoff
- Start date
-
Sounds good. Meantime, happy holidays everyone and merry Christmas.
Newbomb Turk
Well-Known Member
You need to stop the octane booster. Or if you are dead set on using it, cut it way back. Like one ounce to five gallons.
All the orange you see is MMT overload. You just don’t need that much of it.
All the orange you see is MMT overload. You just don’t need that much of it.
Nope. Perfectly normal. .....and you SHOULD have an amp gauge unless it's been modified.
Damn fish
Active Member
Ok do you have air bleed jets if not you are wasting time changing main jets. With 20 inches of vacuum yo⁸u are pulling to much fuel
Damn fish
Active Member
You need a larger air bleed
Newbomb Turk
Well-Known Member
A larger main air bleed will make it fatter, sooner.
He has a lot to do before getting after the MAB.
I don’t use over a .028 MAB on anything.
Damn fish
Active Member
I beg to differ a larger air bleed mixes more air with the fuel so how would that make it richer
Damn fish
Active Member
And the main air is not what needs to be changed. Too much draw on the transition slot
A larger air bleed creates more vacuum which in turn pulls more fuel in faster.
I tend to agree. I try to START by getting the IFRs correct first and then move on from there.
Damn fish
Active Member
More air makes a leaner emulsion
Not in this case.
I'm sure I won't convince you, but imagine this. It's the same effect when you come off the transfer slots and get into the power circuit. It pulls more fuel in quicker due to a stronger vacuum signal. All you have to do is look at a carburetor diagram and it jumps right out at you.
Here. Look at this. You can see that a bigger air bleed will pull in more fuel quicker than a smaller one. Putting in a smaller bleed will slow the fuel down. More air = more pull on the fuel. Less air = less pull on the fuel.
Newbomb Turk
Well-Known Member
I hate to say it but you are wrong. Don’t feel bad. There is a ton of misinformation on this out there.
The main air bleed functions from pressure differential.
At low air flow (like before the booster starts) the MAB acts like emulsion and starts the booster sooner because more air in the emulsion well make the fuel lighter. Lighter fuel is easier to lift up the main well and out to the booster.
A bigger MAB will start the booster sooner, and therefore the engine will be richer sooner.
At higher air flow (after the booster starts) the MAB acts like an air bleed and it reduces the signal the booster sees.
We do not add emulsion to change the air/fuel ratio. Simple math finding the area of the emulsion bleeds and the MAB will show you can’t possibly add enough air from emulsion to affect the air/fuel ratio.
So your assumption that a bigger MAB adds enough air to make the engine leaner (or richer depending on if you go to a smaller one) isn’t true.
I already explained how to clean up the T slot issue. It needs T slot restricters.
For the record a bigger MAB starts the booster sooner and that makes the engine richer, sooner.
A smaller MAB will delay the start of the booster and that makes it leaner, longer.
When I see .033 and bigger MAB’s I know the rest of the carb is probably wrong too.
Damn fish
Active Member
Good example more air being mixed with the same amount of fuel. More air through the bleed less vacuum pulling on the idle fuel slot
Damn fish
Active Member
The inner air bleed. Not the. Mab
Newbomb Turk
Well-Known Member
He can trim the idle air bleed down if he wants.
But the OP said the idle feed restricters are at the top of the well. He needs to move them down first.
An interesting thing that happens when you get too much emulsion. It’s called “slugging” and what happens is there is so much air introduced into the fuel in the main well that the little bubbles coalesce into big bubbles.
When that happens you get a big “slug” of mostly air and then you get a big “slug” of mostly fuel. Yo can see this very clearly in the air/fuel ratio. It will have a saw tooth pattern. That’s a sure sign of slugging.
I mention that because when the idle feed restricters are at the top of the well and not at the bottom where it should be, and because at the top the idle feed restricters (jets) don’t have a head of fuel over them you get the same slugging.
It makes it difficult to get the idle correct idle when that is happening.
Any time I find the IFR at the top I move them down before I change anything else.
So what do you do with the top holes where the IFRs WERE?
Newbomb Turk
Well-Known Member
Ok, but you have to drill and tap the bottom, right? What size tap?
Why would you think the fuel flow stays consistent?
2 very different designs. The Idle circuit has a set jet and air bleed. The Main circuit is a variable airflow design as as the fuel level changes airflow rates change with the introduction of more air (emulsion)
The submerged jet sees constant pressure therefore it does a better job of metering.
Newbomb Turk
Well-Known Member
For those who can't get imperial use 3mm brass grub screws
-
