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

[jmanhoff]

Okay so to clarify what my first group of steps will be.

Close the secondaries completely then crack them so they don’t stick.

Secondary idle mixtures out just a hair.

IFR to the bottom of the metering block.

Middle emulsion port blocked off. (Primary secondary or both?)

Then basically just measuring every hole in the metering blocks?

 

[Newbomb Turk]

Yeah I saw that on one of the forums posted earlier in this thread. Seems to be a universally disagreed on thing why they were moved to the top lol.

I’ll ask my mentor today if he knows why they IFR’s are at the top of the well.

He may have told me and I have forgotten it.

I’m the end, they need to be down. NACA 49 covers this.

What’s sad is most every Holley and Holley clone has them up high. At least for off the shelf carbs.

Monkey see, monkey do. The smart monkey questions why things are done.

 

[Mattax]

I’ll ask my mentor today if he knows why they IFR’s are at the top of the well.

He may have told me and I have forgotten it.

I’m the end, they need to be down. NACA 49 covers this.

What’s sad is most every Holley and Holley clone has them up high. At least for off the shelf carbs.

Monkey see, monkey do. The smart monkey questions why things are done.

I think there's a couple reasons they were used for specific applications. He's posted about it. IIRC one was a Chrysler emissions setup. Another may have been to get an acceleration shot like the restriction in the secondary metering plates can provide.
Follow the breadcrumbs back to post 23 at RFS

 

[Mattax]

Okay so to clarify what my first group of steps will be.

On the carb. First step is to check fuel level.

On the engine. Timing.

For you. Read up on how a carb works.

 

[jmanhoff]

On the carb. First step is to check fuel level.

On the engine. Timing.

For you. Read up on how a carb works.

Fuel level is just about halfway up the sight glass with the engine running.

Timing is 16.

Man I hate reading

Also randomly the dieseling is back I haven’t even touched anything in a couple of hours lol and it hasn’t been an issue until now.

 

[jmanhoff]

Just clocked that you may have meant the timing curve, that’s also on my to do list

 

[Mattax]

Not seeing reversion on the baseplate. IFR location is probably not a major player in this case. I see no harm in lowering it though.
Well go back and read what I wrote 'cause I hate typing if your not reading.
16 at what? 16 at 1000 is probably something else at 900 or 700.
Halfway on a large sight glass is usually the nromal starting point. Bottom of the small sight glass on most older bowls.
Running or engine off the fuel level should be about the same. If not there's a leak.

 

[TT5.9mag]

Not seeing reversion on the baseplate. IFR location is probably not a major player in this case. I see no harm in lowering it though.

It’s pretty new with low run time, I’m guessing.

 

[Mattax]

It’s pretty new with low run time, I’m guessing.

True.
Still with strong vacuum, a close to factory cam, would like to think this engine should be strong at low rpm.

 

[jmanhoff]

Not seeing reversion on the baseplate. IFR location is probably not a major player in this case. I see no harm in lowering it though.
Well go back and read what I wrote 'cause I hate typing if your not reading.
16 at what? 16 at 1000 is probably something else at 900 or 700.
Halfway on a large sight glass is usually the nromal starting point. Bottom of the small sight glass on most older bowls.
Running or engine off the fuel level should be about the same. If not there's a leak.

I’ll go poke around again at your posts. It’s 16 degrees at 900rpm

 

[Mattax]

PS Reading what Chrysler wrote (they have plenty of pics too) is a lot better than reading what some magazine writer thinks he knows. And who are we? some strangers on a forum. If you want to tune, you have to learn how the thing works, and how it relates to the combustion. Timing and fuel mix goes hand and hand.

 

[jmanhoff]

It’s pretty new with low run time, I’m guessing.

I have just under 9000 miles since putting on the carb. I did run the seafoam treatment through both the throat of the carb and in the fuel tank to see if there was just carbon buildup causing the dieseling.

 

[TT5.9mag]

I have just under 9000 miles since putting on the carb. I did run the seafoam treatment through both the throat of the carb and in the fuel tank to see if there was just carbon buildup causing the dieseling.

Ok that’s a lot more run time than I thought you had on it.

 

[Mattax]

Dieseling indicates there's lots of O2 and fuel still getting in the intake with the throttle shut, and enough heat or hot carbon in the cylinders or heads to set it off. Exactly why in you're case IDK.

 

[jmanhoff]

Ok that’s a lot more run time than I thought you had on it.

Yeah it’s been my daily driver since the motor was put in in August. Doesn’t help that I do dominos delivery in it lol (yes it’s not ideal at all for this setup but I’m in college so it was an easy job to find).

That’s also why I have so many driveability updates because well I’m driving it a lot lol.

 

[jmanhoff]

Dieseling indicates there's lots of O2 and fuel still getting in the intake with the throttle shut, and enough heat or hot carbon in the cylinders or heads to set it off. Exactly why in your case IDK.

Yeah I have the throttle a half turn out from fully closed, the idle is running rich but I read it cuts off some of the air so it helps, and I’m running 93 octane currently.

 

[mopowers]

Can we just pool some funds for one of you to travel to this guy's house and get it going for him?

 

[jmanhoff]

Can we just pool some funds for one of you to travel to this guy's house and get it going for him?

Haha that would be awesome lol. I think I had someone’s phone number to text I’m not sure st the top of my head who it was. One of the frequent posters on here

 

[mopowers]

Haha that would be awesome lol. I think I had someone’s phone number to text I’m not sure st the top of my head who it was. One of the frequent posters on here

I'll concede that I haven't read every reply on here, but I know how confusing it can be when multiple people are throwing out advice. Just take a systematic approach and you'll get it figured out. These carbs aren't rocket science. I'd just suggest getting the ignition timing figured out first before you tackle the carb or you'll be doing it all over again.

 

[jmanhoff]

Yeah, I’m taking things in stages. Though I think I may have a blown out pump diaphragm I’m not too sure. I took a crude video but I think it gets the point across. Very weak shot.

 

[Newbomb Turk]

Yeah, I’m taking things in stages. Though I think I may have a blown out pump diaphragm I’m not too sure. I took a crude video but I think it gets the point across. Very weak shot.

Yeah that’s bad. You need to sort that out first.

One thing that happens with certain pump cams, like the blue one which IIRC is the most aggressive cam will require you to bend the lever where it rides on the pump cam.

Even changing holes on the pink cam which is what yours looks like, may make the lever not ride flat on the cam. So you bend it to make it right.

I was at the races last year and I saw 3-4 carbs with the pump lever not sitting on the cam correctly.

Not saying it’s your issue. Just a preventative FYI if you need to change pump cams or even the hole that cam is in.

 

[jmanhoff]

Yeah that’s bad. You need to sort that out first.

One thing that happens with certain pump cams, like the blue one which IIRC is the most aggressive cam will require you to bend the lever where it rides on the pump cam.

Even changing holes on the pink cam which is what yours looks like, may make the lever not ride flat on the cam. So you bend it to make it right.

I was at the races last year and I saw 3-4 carbs with the pump lever not sitting on the cam correctly.

Not saying it’s your issue. Just a preventative FYI if you need to change pump cams or even the hole that cam is in.

Yeah it’s pretty annoying because now I have a flat spot for obvious reasons, my remedy as of now is to just richen the idle and it works to a point.

I wonder if while I had the carb off something pushed against the rod and overextended the diaphragm.

I’m also currently chasing the dieseling issue kind of hard to really do anything else while I’m at work. My first thought was the curb idle was too high but it’s barely open now and still does it. Ideally I’d like to not cover the t slot but I dont know what else could be causing enough fuel/air to pull through unless something else is wrong. I backed down the timing to 15 initial and idle is still super high.

 

[jmanhoff]

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?

 

[jmanhoff]

So my plan for tomorrow is to run over to Lowe’s and buy a drill and tap set that has the bits and taps needed for 6-32 and 10-32 so I can drill/tap the emulsion, ifr, etc. I don’t currently have any blanks for the emulsion ports but I’ll probably tap them anyway because I’ll already be in there might as well make a mess once and not twice.

I’m going to move the IFRs on both metering blocks to the bottom ports. Then I’m just going to swap over the diaphragm from the secondary accel pump to the primary just so I actually have a squirter if it is actually the issue.

While I have the carb off I’m going to fully shut them barely crack open the secondary butterflies, then do the same for the secondary idle screws.

I think this will give me a good starting point as it will kind of set the carb at “zero” for future tuning because it seems like a universally agreed upon point in this thread. I do like the idea of running a sooner opening PV so I can potentially run a lower size primary to have a leaner cruise which I would never say no to, but I think that’s too many things to change at once lol.

 

[TT5.9mag]

Before you drill and tap or move anything, go back and read post 254 a few times. You have to have a good understanding of what you’re doing AND WHY you’re doing it. Sort the timing out first because it affects the carb. Then MEASURE everything in your carb. That’s all after making sure the systems are functioning properly, like the accelerator pump circuit.