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

[Newbomb Turk]

Sounds good, so in terms of reading the plugs how do I differentiate between running rich and a rich squirt?

I will say that I can change what a plug looks like in one pull on the dyno or a single pass down the track.

They change way quicker than the current myth.

Go on Amazon and order up a 20 dollar Dr mom otoscope so you can look down into the plug.

Find out what spark mark is, learn how to get it.

I spent an evening at the track with a friend about 16 years ago. He believed the myth that you can’t color a plug in one run or change it in one run.

He had a bad converter and the company that shoved that garbage converter up his butt told him the tune up was off. So we went to the track.

We went from 42 total timing to 32. The ET and MPH never changed. But the plug did. You could see the timing on the plug move in one run.

Then we went up 12 sizes in jet. Everything stayed the same but the plug had color on it and you could see how fat it was.

Then we went down 4 sizes in jet from the starting point. It was lean but it made a full pull. MPH and ET never carried more than .015 and I don’t think it was off more than 1 MPH all night.

He learned two things that night. Three really.

You can read a plug after one pull.

When the tune up changes and the car doesn’t change with it you have issues other than tune up.

Converters matter. Lucky the converter company was local. He went in, slammed that steaming pile of **** on the counter and stood there for three hours until he got his money back.

They also dicked him on changing out first gear. He went from a stock power glide low gear to a 2.0x first gear. That was ignorant because a it did was hit the tire harder.

 

[MOPAROFFICIAL]

A bog upon depression of the throttle will tell you it's too much gas, a lean pop or cutting out for a second will tell you it's too little gas

 

[MOPAROFFICIAL]

I'll see if I can find a 10.5PV somewhere I think I tried ordering during a weird shortage period. IIRC, the secondary metering block on this carb doesn't have a PV port so I would need to buy a new block for it.

I am getting my new exhaust put on Monday meaning I will have ports for o2 sensors to run a wideband and I'm assuming that will tell me whether or not I'm having a lean or rich issue from the squirters? I also think it will help me tune the fuel more. I know people say that you should tune an engine off of what it likes, not an AFR number, which I believe and I have been doing, but I'd imagine I can use the gauge and blip the throttle and watch to see if it jumps up or down to figure out if its rich or lean.

Is this thing at the moment running open headers? If so your tuning is going to change drastically once you get some back pressure involved. The idle speed, for one, will increase in rpm.
It won't need as much fuel either

 

[jmanhoff]

Is this thing at the moment running open headers? If so your tuning is going to change drastically once you get some back pressure involved. The idle speed, for one, will increase in rpm.
It won't need as much fuel either

It is not, currently has the stock y pipe into 2.5 inch, flowmaster super 40, then 2.5 back. Basically the stock exhaust just with a flowmaster. I am on Monday getting a true dual with magnaflow 5” rounds with 2.5 inch all the way back if that makes a difference but I’m not sure it really will.

I bumped up the timing slightly and now it has a slight cut out when I blip the throttle again sounding like the engine completely cuts, but it also feels like it has a flat spot when I accelerate.

It’s also still dieseling which is a problem that seems to come and go. Right now I’m running 93 octane and idle is set to 750, vacuum is 20 inches.

 

[RustyRatRod]

It is not, currently has the stock y pipe into 2.5 inch, flowmaster super 40, then 2.5 back. Basically the stock exhaust just with a flowmaster. I am on Monday getting a true dual with magnaflow 5” rounds with 2.5 inch all the way back if that makes a difference but I’m not sure it really will.

I bumped up the timing slightly and now it has a slight cut out when I blip the throttle again sounding like the engine completely cuts, but it also feels like it has a flat spot when I accelerate.

It will certainly make a difference in how it's tuned. No question about it.

 

[jmanhoff]

It will certainly make a difference in how it's tuned. No question about it.

Well I guess it’s a good thing I planned to wait until after the exhaust is done before I start digging into the bleeds and internals lol.

 

[jmanhoff]

Here’s a video of the vacuum gauge, pressing the throttle a little under half

 

[RustyRatRod]

Here’s a video of the vacuum gauge, pressing the throttle a little under half

That tells you nothing. Nada. Zilch. Get the car up to cruise speed. 55 is a great speed. Keep it STEADY at 55 with your foot BARELY on the gas just enough to keep it at speed on a flat, level surface and then take your cruise vacuum reading and write it down so you don't forget.

 

[jmanhoff]

That tells you nothing. Nada. Zilch. Get the car up to cruise speed. 55 is a great speed. Keep it STEADY at 55 with your foot BARELY on the gas just enough to keep it at speed on a flat, level surface and then take your cruise vacuum reading and write it down so you don't forget.

I forgot to add to the caption that was the cut out I was hearing, you can hear it in the video I just put the gauge in as reference to throttle. My cruise vacuum is about 18 or so that’s how I got the 9.5 PV along with where it starts to struggle.

 

[RustyRatRod]

I forgot to add to the caption that was the cut out I was hearing, you can hear it in the video I just put the gauge in as reference to throttle. My cruise vacuum is about 18 or so that’s how I got the 9.5 PV along with where it starts to struggle.

Then, if you're trying to choose a power valve based on cruise vacuum, I'd try a 12.5. Idle vacuum you would probably be looking at the proverbial 6.5 Holley recommends for everything. With 18 hg cruise vacuum, you probably don't need to tune for cruise vacuum. But you can certainly try it.

 

[jmanhoff]

Then, if you're trying to choose a power valve based on cruise vacuum, I'd try a 12.5. Idle vacuum you would probably be looking at the proverbial 6.5 Holley recommends for everything. With 18 hg cruise vacuum, you probably don't need to tune for cruise vacuum. But you can certainly try it.

Yeah I might order a 10.5 and a 12.5 and see what it’s happier with. Does that slight cut sound like it’s too lean or too rich though?

 

[RustyRatRod]

Yeah I might order a 10.5 and a 12.5 and see what it’s happier with. Does that slight cut sound like it’s too lean or too rich though?

Chit man, don't ask me. My hearing is terrible. What PV does it have NOW?

 

[jmanhoff]

Chit man, don't ask me. My hearing is terrible. What PV does it have NOW?

Lol well for reference I guess it literally sounds like the exhaust sound cuts out for a second then it comes back.

Currently have a 9.5PV

 

[RustyRatRod]

Lol well for reference I guess it literally sounds like the exhaust sound cuts out for a second then it comes back.

Currently have a 9.5PV

Do you HAVE the 6.5 PV that it likely came with? If so, my recommendation is to try that first and see if you can tune to it. Usually, engines with low vacuum from large camshafts benefit from cruise......although that's not written in stone. So my recommendation is to try with a 6.5, then if you cannot get it like you want it, maybe look at a 12.5. Are you 100% SURE of that 18hg at cruise? That's important.

 

[jmanhoff]

Do you HAVE the 6.5 PV that it likely came with? If so, my recommendation is to try that first and see if you can tune to it. Usually, engines with low vacuum from large camshafts benefit from cruise......although that's not written in stone. So my recommendation is to try with a 6.5, then if you cannot get it like you want it, maybe look at a 12.5. Are you 100% SURE of that 18hg at cruise? That's important.

I chose the 9.5 because when I went down to 66 primary jets (which yielded the best color plugs), it started to struggle right at 10 inches. The PV it had (6.5) really never opened it felt like. I have to really push the throttle to get the vacuum low enough to open it.

In terms of the vacuum yeah I’m certain of it being around 18. I drive on a road almost every day that is a 55 and I look at the gauge quite a bit and it’s almost always at 17-20 light throttle

 

[TT5.9mag]

The “cut out” as you refer to it is a lean stumble that is caused by air speed changing rapidly through the Venturi and the fuel flow not being able to catch up to it quick enough. You need idle, transfer slot, and squirter tuning. Like we’ve been telling you for multiple pages now. We still don’t know what the timing is and have no idea what the tune up in the carb is currently.

 

[MOPAROFFICIAL]

Yeah I might order a 10.5 and a 12.5 and see what it’s happier with. Does that slight cut sound like it’s too lean or too rich though?

Whats the vacuum reading , in gear n foot on brakes? Choose a pv half of that or one step above half.
Make sure there is no gap between the pump lever and diaphragm and MAYBE try a diff color pump cam. Wouldn't think this would need a big shooter, there's a ton of vac and no high stall convertor, or is there?

 

[jmanhoff]

The “cut out” as you refer to it is a lean stumble that is caused by air speed changing rapidly through the Venturi and the fuel flow not being able to catch up to it quick enough. You need idle, transfer slot, and squirter tuning. Like we’ve been telling you for multiple pages now. We still don’t know what the timing is and have no idea what the tune up in the carb is currently.

I’m assuming by idle and t slot tuning you mean in the metering block? I plan to graph out the timing soon once I get everything situated.

Whats the vacuum reading , in gear n foot on brakes? Choose a pv half of that or one step above half.
Make sure there is no gap between the pump lever and diaphragm and MAYBE try a diff color pump cam. Wouldn't think this would need a big shooter, there's a ton of vac and no high stall convertor, or is there?

It’s a manual, if it matters it’s the stock flywheel and clutch setup you would find on a manual 5.9 gas 1500

I may order the pump cam set but I think I should at least pin out every hole in this carb and get that data posted first before I do anything like that

 

[jmanhoff]

Apologize for being all over the place I’m currently at work so I’m going back and forth lol so a lot of the previous posts are kind of blurred for me right now

 

[jmanhoff]

If it helps at all, being I bought the carb brand new, it still has the stock setup so it would be a 28/28 high speed air bleed and a 70/70 idle air bleed

 

[RustyRatRod]

I would get the carburetor back to 100% STOCK like it came and try to adjust everything from there.

 

[jmanhoff]

I would get the carburetor back to 100% STOCK like it came and try to adjust everything from there.

Would the fact that with stock jetting it would get 6mpg on the highway and smoke like a diesel over 50% throttle change your mind? Thats where I started lol. 71 primaries and 74 secondaries is what did that.

 

[RustyRatRod]

Would the fact that with stock jetting it would get 6mpg on the highway and smoke like a diesel over 50% throttle change your mind? Thats where I started lol. 71 primaries and 74 secondaries is what did that.

Ok. Carry on.

 

[jmanhoff]

Ok. Carry on.

I think tonight and tm I’m going to read up on all the posted forums about air bleeds and what not and go from there.

I also saw something about moving where the idle fuel feed is? I think from the top of the metering block to the bottom? I think it was moved for whatever reason on newer carbs and it’s better to have it lower because it’s fully submerged in fuel?

 

[RustyRatRod]

A 650 dp on a 5.9 Magnum should be DAMN close. If it was truly puking black smoke out, what you should have done was sent it back. Something is WRONG.