Fine Tuning a 360 Magnum with a Brawler "Double Pumper"

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Everytime you change the throttle blade position for and increase or decrease in idle speed, you'll need to reset the mixture screws. You want them both primary secondary to be the same. With what you're doing, you shouldn't have to mods to the carburetor.
 
Okay so I’m gonna ask here because google doesn’t seem to be very helpful lol it’s just flooding me with the wrong topics.

When the diaphragm is broken it would leak fuel externally of the carb correct?

If so, and I don’t have a leak, what else could be causing the weak shot? I feel like if it was clogged it wouldn’t be able to depress the diaphragm right?

There is a check valve under the pump nozzle. They can get stuck but usually they don’t pass any fuel.

That’s about the only other thing I can think of.
 
Would those higher vacuum PVs work then even though they’re “not for gasoline”?
They don't care or know if it's gas or alcohol. Engine only cares it's getting enough fuel to not go lean.

Stick a 15.5 in it before you drill anything.
Seems unnecessary to mod anything with a stock cam/ high vac situation.
Makes sense it can't handle much initial w/o pinging. Jmo
 
Will do more re-reading at work but I took the carb off to swap the pumps and to close the secondaries and the screw is out until it is loose then barely turned in so the butterflies just start to move

It looks like I need to drill out the restrictor holes to a larger size but it also looks like the brass wouldn’t fit in the channels unless it’s an illusion.
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Regardless, I ran out of time to do the drilling so Ill have to push it off to another day.
 
There is a check valve under the pump nozzle. They can get stuck but usually they don’t pass any fuel.

That’s about the only other thing I can think of.
I think it’s the diaphragm I swapped them and it has a squirt now. Still have a slight stumble on quick throttle but that’s probably a pump cam issue now? Not entirely sure.
 
They don't care or know if it's gas or alcohol. Engine only cares it's getting enough fuel to not go lean.

Stick a 15.5 in it before you drill anything.
Seems unnecessary to mod anything with a stock cam/ high vac situation.
Makes sense it can't handle much initial w/o pinging. Jmo
I might drop the timing back down so I have more control over the idle. What else can technically control idle speed other than curb idle, idle mix, and timing? IFR?

Should I put in a 15.5 and block off the middle emulsions?
 
I’ve been messing with the pump cam settings, each time checking the tolerance to 0.010” at WOT, and it still falls flat on its face on a hard acceleration, quick throttle, or if I don’t shift like a grandma in a Lincoln lol. It has a pretty bad off clutch stumble I can hear the exhaust cut out and the nose dips for a second when I let out the clutch.

It seems to have a nice clean shot when I open the throttle a lot but not really at a small input to the throttle. Smooth throttle input it’s pretty smooth maybe a slight stumble for a split second right at the start so it sounds like it’s transitioning well it’s just not able to fill the gap.

From what I’ve read that sounds like a pretty strong candidate for a cam change? I can get a stronger squirt at idle if I “preload” the pump arm but that also would be bottoming it out at WOT I would think.

I think I already mentioned this too but I have to keep the idle super fat for it to I guess provide enough fuel for the transition, if I lean it out where it’s happy well for one it idles super high and it barely can get moving. Come to think of it maybe I somehow blew out a power valve?
 
I’ve been messing with the pump cam settings, each time checking the tolerance to 0.010” at WOT, and it still falls flat on its face on a hard acceleration, quick throttle, or if I don’t shift like a grandma in a Lincoln lol. It has a pretty bad off clutch stumble I can hear the exhaust cut out and the nose dips for a second when I let out the clutch.

It seems to have a nice clean shot when I open the throttle a lot but not really at a small input to the throttle. Smooth throttle input it’s pretty smooth maybe a slight stumble for a split second right at the start so it sounds like it’s transitioning well it’s just not able to fill the gap.

From what I’ve read that sounds like a pretty strong candidate for a cam change? I can get a stronger squirt at idle if I “preload” the pump arm but that also would be bottoming it out at WOT I would think.

I think I already mentioned this too but I have to keep the idle super fat for it to I guess provide enough fuel for the transition, if I lean it out where it’s happy well for one it idles super high and it barely can get moving. Come to think of it maybe I somehow blew out a power valve?


You didn’t blow a power valve.

Here is my last advice and then I’m tapping out because you are trying to ride 5 different horses with one ***.

Plug that motherfucking middle emulsion hole if it’s actually open.

Move the IFR down where the science over 100 years ago says it should be. It would be no bigger than .030 if I was doing it and I’d probably go down to .028 if I was doing it myself.

Measure the main air bleed. The smaller bleed of the two on top of the carb. If it’s bigger than .026 drill it out and thread it for a 10/32 set screw and make it .026.

Then start tuning again.

You are trying to cut corners and hope that some bullshit internet myth that you have a pump shot issue will magically work itself out. It won’t.

I’ve done bunches of these carbs and they all come with different tune ups in them and none of them are worth a rusty ****.

I’m telling you how to START fixing it. You have a bunch of work to do once you unfuck what you have as far as I’ve said.

And get some T slot restricters in there. Start at .078 and tune from there. You will probably end up in the mid .060’s bit work your way there and learn as you go.

Just for the record on my tunnel ram **** with the correct booster I can use one .026 emulsion bleed. You don’t need three emulsion holes open unless you want to spend several days on the dyno flogging that **** out.

And measure the idle air bleed so you can see how hacked up that is.

You haven’t measured much so we are all grabbing our asses trying to guess on what you have.
 
You didn’t blow a power valve.

Here is my last advice and then I’m tapping out because you are trying to ride 5 different horses with one ***.

Plug that motherfucking middle emulsion hole if it’s actually open.

Move the IFR down where the science over 100 years ago says it should be. It would be no bigger than .030 if I was doing it and I’d probably go down to .028 if I was doing it myself.

Measure the main air bleed. The smaller bleed of the two on top of the carb. If it’s bigger than .026 drill it out and thread it for a 10/32 set screw and make it .026.

Then start tuning again.

You are trying to cut corners and hope that some bullshit internet myth that you have a pump shot issue will magically work itself out. It won’t.

I’ve done bunches of these carbs and they all come with different tune ups in them and none of them are worth a rusty ****.

I’m telling you how to START fixing it. You have a bunch of work to do once you unfuck what you have as far as I’ve said.

And get some T slot restricters in there. Start at .078 and tune from there. You will probably end up in the mid .060’s bit work your way there and learn as you go.

Just for the record on my tunnel ram **** with the correct booster I can use one .026 emulsion bleed. You don’t need three emulsion holes open unless you want to spend several days on the dyno flogging that **** out.

And measure the idle air bleed so you can see how hacked up that is.

You haven’t measured much so we are all grabbing our asses trying to guess on what you have.
Okay so next to do is order some 6-32 blanks or set screws I guess they’re really the same thing.

Tap the middle emulsions and plug them with a blank. (Both primary and secondary side?)

Move the IFR (ignore my post about it fitting because I looked at the wrong hole)

Will a 6-32 blank work for t slot or should I use #10?

I did look at the bleeds at the top and they are stamped as listed on the spec sheet, 70/70 for idle and 28/28 for high speed. How much that actually matters not entirely sure, but it is accurate to the spec sheet unlike my PMJs which were larger than listed.
 
Also are there any recommended drill bit sets I get for holes in thousandths? I can’t find any that aren’t metric or fractions
 
I might drop the timing back down so I have more control over the idle. What else can technically control idle speed other than curb idle, idle mix, and timing? IFR?

Should I put in a 15.5 and block off the middle emulsions?
A vacuum leak.lol
 
Also are there any recommended drill bit sets I get for holes in thousandths? I can’t find any that aren’t metric or fractions
You will have to go online and find the conversion, in thousandths. I would bet a lot of that stumble is because you have too much T-slot exposed.
 

Also are there any recommended drill bit sets I get for holes in thousandths? I can’t find any that aren’t metric or fractions
I have this one for the small sizes. Shows number and measured size for each from 1-60. I’d also recommend getting a number zero or number one center drill to start the holes so the drill doesn’t wander and drill straight without breaking. Just need to use the center drill to put a dimple in the brass that the drill can use as a guide to get started. There can be a trick to drilling small holes. You need to be patient and pet drill clearing the flute often.

Irwin Tools IRWIN Drill Bit Set, 60-Piece (80181) https://a.co/d/bfv0OuF
 
I have this one for the small sizes. Shows number and measured size for each from 1-60. I’d also recommend getting a number zero or number one center drill to start the holes so the drill doesn’t wander and drill straight without breaking. Just need to use the center drill to put a dimple in the brass that the drill can use as a guide to get started. There can be a trick to drilling small holes. You need to be patient and pet drill clearing the flute often.

Irwin Tools IRWIN Drill Bit Set, 60-Piece (80181) https://a.co/d/bfv0OuF
Awesome, thanks for the link I’ll take a look soon. Just got home after a strange ordeal.

I started to smell gas so I pulled over at a gas station conveniently and right as I rolled into the lit up area the engine died. Popped the hood, took off the air cleaner and the primary side of the carb was literally flooded with gas up to the boosters.

No idea why that happened, maybe it blew a seal on the bowl? But regardless I messed around with it, checked fuel pressure and it’s right at 6.5-7psi. Though once I started driving again after blowing all the gas out the spark plugs I noticed my volt meter bouncing around like crazy and at the high end it was beyond where it normally is (and this alternator/regulator combo is a “happy” one so to speak, it runs high). So maybe the regulator or alternator is going bad, caused high voltage to the pump, and the pressure burst the float?

Need to take a look tomorrow when I have daylight. Going to measure the voltage and what not. Right now as a bandaid I have the float screw all the way in and it’s just above halfway on the sight glass. Though it’s weird the secondary side was perfectly fine.
 
Sounds like something stuck the needle open.
 
Would you say it’s normal to have the adjustment screw all the way in or is it really a case-by-case adjustment that’s never the same on two carbs
If you’re talking about the needle, aka float level adjustment, no that’s not normal. Usually there’s 3-4 threads sticking out the top of the bowl.
 
If you’re talking about the needle, aka float level adjustment, no that’s not normal. Usually there’s 3-4 threads sticking out the top of the bowl.
I’ll add that to the list to check tomorrow. That may be where it is right now I’m not entirely sure, I set it where it was halfway in on the sight glass or as close as I could get it to there
 
6.5 -7 in my opinion way to high. It's not pressure you want it's volume. 5PSI is plenty. You want the fuel going into the bowl like a garden hose flow not spraying in.
Sounds like the needle and seat needs replaced.
 
Keep the fuel psi around 3.5-6psi
You'll see the low end during wot

Needle and seat, make sure that's good or else the pump will "pump" the full psi through the boosters and flood the engine.
 
6.5 -7 in my opinion way to high. It's not pressure you want it's volume. 5PSI is plenty. You want the fuel going into the bowl like a garden hose flow not spraying in.
Sounds like the needle and seat needs replaced.
I need to mess with the regulator, I got a Holley deadhead regulator and I have the screw all the way out (lowest pressure) and it seems like it’s still above 6. The pump I have is a 5-9psi electric pump so I wouldn’t think it’s overpowering the regulator
 
Alright so forgive me for asking a million questions but I’m trying to see if I’m truly grasping the fuel circuits.

So the idle circuit contains the IFR and idle air bleed, and it controls the idle circuit and the transfer circuit. Low speed, low throttle situations are running on this circuit.

The main circuit includes the main air bleed, emulsions and main jets and isn’t really doing anything until 2500ish rpm when the Venturi is strong enough to pull the fuel through the boosters.

The emulsion ports are mixing air and fuel through the PMJ and air bleed and sending it through the booster, and any ports above the bowl level are mixing air, below the bowl are mixing fuel. So blocking off the middle port which is right at the fuel level will essentially make it a 1:1 mix of air and fuel (I know it’s not literally what’s happening but 1 hole is fuel, one is air so that’s my idea for the 1:1 ratio.)

Is that the correct or at least right track logic?

I’m also planning on just buying some brass set screws most likely, I’m assuming brass is the universally accepted material. Should I go with 1/4 long or 1/8 long?
 
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