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

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Hysteric said:
Pull the spark plugs out and look at the centre electrode surface where the spark jumps across and post some photos.
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I have this picture from after quite a bit of cruising with the #66 jets, still with 14 degrees of timing. I’ll take another picture once i get back from the store.

I drove over to Lowe’s with the timing set at 10 and it feels a little peppier off idle but it’s significantly less quick at WOT. Someone asked why I had VA hooked to full manifold but if I’m not mistaken doesn’t the timed port give vacuum based on how much throttle is open? So that would mean that theoretically at WOT once timing is all in I would be at almost 50 degrees?

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jmanhoff said:
I have this picture from after quite a bit of cruising with the #66 jets, still with 14 degrees of timing. I’ll take another picture once i get back from the store.

I drove over to Lowe’s with the timing set at 10 and it feels a little peppier off idle but it’s significantly less quick at WOT. Someone asked why I had VA hooked to full manifold but if I’m not mistaken doesn’t the timed port give vacuum based on how much throttle is open? So that would mean that theoretically at WOT once timing is all in I would be at almost 50 degrees?

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No, because vacuum drops off when the throttle is open. That said, it's not uncommon for timing to be "around" 60 degrees at part throttle when the vacuum advance is activated. Perfectly normal.
 
You need to take a close up of the plug in sunlight to be able to see it clearly.
 
RustyRatRod said:
No, because vacuum drops off when the throttle is open. That said, it's not uncommon for timing to be "around" 60 degrees at part throttle when the vacuum advance is activated. Perfectly normal.
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I mean when it’s hooked to ported vacuum, or “timed vacuum” as it’s called on the diagram. It’s the port that gets the same Venturi as the jets I believe? Manifold vacuum decreases under load but Venturi “vacuum” increases does it not?
 
jmanhoff said:
I mean when it’s hooked to ported vacuum, or “timed vacuum” as it’s called on the diagram. It’s the port that gets the same Venturi as the jets I believe? Manifold vacuum decreases under load but Venturi “vacuum” increases does it not?
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No. Not under load. Under no load or part throttle it's there, but it's still controlled by the throttle opening. There's only 1 vacuum source and it all drops off under load.
 
RustyRatRod said:
No. Not under load. Under no load or part throttle it's there, but it's still controlled by the throttle opening. There's only 1 vacuum source and it all drops off under load.
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So does it make more sense to run the VA on ported vacuum or manifold vacuum? Or is that really dependent on how the engine reacts to each?
 
jmanhoff said:
I mean when it’s hooked to ported vacuum, or “timed vacuum” as it’s called on the diagram. It’s the port that gets the same Venturi as the jets I believe? Manifold vacuum decreases under load but Venturi “vacuum” increases does it not?
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Ported vacuum will only see vacuum when the throttle blade is passing it, i.e when you're cruising on the Tslot
 
Maybe I missed it but why use a double pumper carburetor on a street vehicle that will spend 80% of the time at part throttle?
 
jmanhoff said:
So does it make more sense to run the VA on ported vacuum or manifold vacuum? Or is that really dependent on how the engine reacts to each?
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I would run it whichever it runs best on. Some people insist on one or the other, but I wouldn't box myself in like that. Usually, lower compression engines with lumpy cams react better using manifold vacuum. The extra timing pulled in at idle and part throttle helps for a complete burn and keeps the plugs clean. Whichever way it runs best is how I normally do it.
 
Hysteric said:
What's the voltage output of the alternator when its at idle?
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About 13.6-13.8. My alternator is going out though so it fluctuates a lot, I’ve had this issue prior to doing the engine swap just have been bouncing between getting a HD alternator or stock replacement.

Also can I have reasons why people say don’t use a mechanical secondary carb on a street car? Vacuum secondary carbs open the secondaries when there is low vacuum (IE under load), correct? And mechanical secondaries only open when you open them (like over half throttle like mine are set I believe, I can feel it in the pedal when I hit the second set of springs). So why would it make a difference economy wise between the two if part throttle on a mechanical secondary never opens them? Or was that a question on why would I run a mechanical secondary carb on a street engine in general?
 
jmanhoff said:
About 13.6-13.8. My alternator is going out though so it fluctuates a lot, I’ve had this issue prior to doing the engine swap just have been bouncing between getting a HD alternator or stock replacement
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What people don't understand is ignition strength affects the burn. I have seen half a volt (0.5v) drop in alternator output change the spark plug from looking good to flat out looking rich and read richer in AFR (innovate 02's) but in actual fact the AFR didn't change.

Before you even approach tuning the carb sort out the alternator and make sure you are getting enough power to your ignition box.

Aim to get about 14.4v output from your alternator at idle.
 
Hysteric said:
What people don't understand is ignition strength affects the burn. I have seen half a volt (0.5v) drop in alternator output change the spark plug from looking good to flat out looking rich and read richer in AFR (innovate 02's) but in actual fact the AFR didn't change.

Before you even approach tuning the carb sort out the alternator and make sure you are getting enough power to your ignition box.

Aim to get about 14.4v output from your alternator at idle.
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I’ll check voltage again in a minute, I’m going to go pull a plug and take a peak. I really only get alternator issues at idle, once I’m driving it’s fine. I notice the headlights and dash dim and the voltage gauge drops down but when I’m moving it’s where it normally is.
 
jmanhoff said:
I’ll check voltage again in a minute, I’m going to go pull a plug and take a peak. I really only get alternator issues at idle, once I’m driving it’s fine. I notice the headlights and dash dim and the voltage gauge drops down but when I’m moving it’s where it normally is.
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That's normal Chrysler electrical bullcrappary.
 
RustyRatRod said:
That's normal Chrysler electrical bullcrappary.
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Yeah my voltage gauge drops when my blinkers are on lol so I’m sure part of it is a bad ground, but doesn’t hurt to check. I think I’ll be getting a new alternator anyway because I want to run dual batteries with a beefy inverter (it’s a work truck but not slow is the goal here).
 
jmanhoff said:
Yeah my voltage gauge drops when my blinkers are on lol so I’m sure part of it is a bad ground, but doesn’t hurt to check. I think I’ll be getting a new alternator anyway because I want to run dual batteries with a beefy inverter (it’s a work truck but not slow is the goal here).
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Find an alternator that's rated around 100A to 120A
 
Hysteric said:
Find an alternator that's rated around 100A to 120A
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I found one from ACDelco off of good old rockauto that’s 120 so I’ll probably end up with one of those. I’ve had nothing but bad luck with reman. Alternators so I’d like a new one if I can find one lol
 
That looks good if a little on the rich side. What's the gap?

Are you using octane booster?
 
Hysteric said:
That looks good if a little on the rich side. What's the gap?

Are you using octane booster?
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Gap is 35, same plugs as came stock and what dodge recommends.

I usually do yeah, when I don’t I have dieseling issues but the booster works well enough. The current tank has no booster however, 87 octane.
 
jmanhoff said:
Gap is 35, same plugs as came stock and what dodge recommends.

I usually do yeah, when I don’t I have dieseling issues but the booster works well enough. The current tank has no booster however, 87 octane.
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If you have a look at the pic of the plug see how its consistent all the way through out from the strap all the way down to the porcelain. That tells you the mixture is well vaporized. That's a great plug read if the fuel doesn't contain octane booster
 
Hysteric said:
If you have a look at the pic of the plug see how its consistent all the way through out from the strap all the way down to the porcelain. That tells you the mixture is well vaporized. That's a great plug read if the fuel doesn't contain octane booster
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That is with the 66 jets I haven’t yet changed anything internal. Does that mean it kind of invalidates the idea of changing the jets back to stock?
 
I cant see a lot on my phone but l’ll ck it out when I get home. How far are u from Johnson City Tn.
 
LO23M8B said:
I cant see a lot on my phone but l’ll ck it out when I get home. How far are u from Johnson City Tn.
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Currently at home in northern Virginia, but go to school in Radford so I’m almost at the southwestern tip. 2 hours from school on a good day? 81 is 81 so it’s a turkey shoot lol.
 
Well bless my soul what in the world did Holley do to their carbs. Some pencil neck trying to save money. If you would like to talk tomorrow sometime, I'll send you my number on a pm we have a lot to discuss.
 
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