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Thread: 2.4 with an SSD and a 45DCOE

  1. #41
    ggl
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    Quote Originally Posted by The Scifi Guy View Post
    Okay, let's take a look at the air paths and air/fuel availability between dual side drafts with one barrel-one cylinder dedicated runners and a single side draft with a shared plenum-shared barrels set up with runners that can pretty much draw from the whole system. For this GT install, I have chosen an old pic of my assortment of 40 DCOE's attached to my shorty Irmscher intakes and my Midikit SSD intake:

    No Gordo lines:




    Gordo lines added showing the angles of the air flow and the added air/fuel availability of the SSD set up:




    The air would of course curve and flow more smoothly through both types of intakes, since they're rounded and flow contoured inside, than my straight lines show. What does it all mean? I'll let you guys tell me. I just posted these pics as a sort of answer to Mikey's question.
    Good pics

    This be somewhat of a Wrench type post but it's not difficult to figure out, all you have to remember is that air has mass. We're moving quite large quantities of air and we're moving it at considerable speed.

    That's one thing to consider

    Fuel is heavier than air

    That's another thing to consider
    "I hate RallyBob"


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    7,000 Post Club My location wrench459's Avatar
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    Quote Originally Posted by ggl View Post
    ..

    Fuel is heavier than air

    That's another thing to consider
    Yepper
    The fuel cant turn the curve as fast as the air column.
    It'll separate and slam into any tight turns walls.
    (edit);Yikes I meant LONG turns
    I think that is has something to due with inertia
    and how completly the fuel is mixed with the air.

    I'll take short FAT straight runners (be it with ITB'S or yuck dual DCOE'S )any day over a SSD.

    Did I say that side drafts and ITB'S sounds as good as they run?
    Last edited by wrench459; 07-02-2015 at 11:18 PM.

    Si vis pacem, para bellum "If you want peace, prepare for war"

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    ggl
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    Quote Originally Posted by wrench459 View Post
    Did I say that side drafts and ITB'S sounds as good as they run?
    It needed to be said though
    "I hate RallyBob"


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    Just Some Dude in Jersey My location The Scifi Guy's Avatar
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    Fine Tuning the Carb Jetting

    Time to return to this thread. As seen in my Gordos's GTX and Gordo Wires the GTX threads, the engine is now installed, most of the wiring and other glitches have been unglitched, and the engine is now running stable and drivable. The car now has a jet coated stock 2.4 cast iron manifold, attached to a jet coated 2.25" custom RallyBob headpipe, and ending with the new OGTS 2" stainless muffler system(Stainless headpipe deleted). I've purchased two books on Weber and side draft specific tuning and I got an oxy sensor and gauge that I can install in the bung of my exhaust manifold to aid the tuning process and just to have a cool gizmo.

    In this faze I will attempt to change the preliminary jetting to improve the carb's performance in the system I currently have.

    For starters, could someone please describe the difference between "surging" and "hunting" as it applies to the "bog" when going off idle? These are common terms being bandied about by various online sources of info about side drafts. One means you're too rich and one means you're too lean, both cause bog-like behavior when transitioning off idle. Knowing the difference between these two behaviors and what to do about it is a talent I need to learn.

    This is the first nut to crack and, as far as I know, only involves the idle transition circuit. As I understand it, side draft idle jets do not control your idle performance, the mixture screws and other stuff do that. The idle jetting somehow controls the conditions as you transition from idle to throttle. The Bog Zone. This is where my current set up needs some help. If I move the throttle too fast it will bog and way too fast it will cough and stall. Some stuff I've read indicates that backfiring through the carb and stalling is indicative of being too lean. Sound right?

    Bob indicated earlier that an SSD set up needs more fuel and what little to be found online about SSD or "Siamese intakes" agrees with this. So I guess that I'll try jetting for more fuel or less air first.
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    Tennessean Site Supporter My location hrcollinsjr's Avatar
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    Quote Originally Posted by wrench459 View Post
    I'll take short FAT straight runners (be it with ITB'S or yuck dual DCOE'S )any day over a SSD.

    Did I say that side drafts and ITB'S sounds as good as they run?
    Did you say you'd take a SSD over a downdraft carb any other day?

    Harold

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    2000 Post Club Site Supporter My location P.J. Romano's Avatar
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    What is your current setup Gordon?
    Old racers never die. They just go bench racing.

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    Owner of EZ2Wire.com My location GoinManta's Avatar
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    Just remember this:



    If you ever decide to get with the times
    CURRENT
    '71 Opel Kadett 4 Door 36D (2.0 L w/ EFI & Auto) - "Mary Ann"
    '74 Opel Manta - "Barbara"
    '05 Pontiac GTO

    In the past owned:
    '06 Pontiac GTO
    2 Bitters (#491/#439)
    '73 Commodore GS
    ATLAS ( 74 Manta w/ 2.8L LK5 )
    '73 Blue Max Manta Luxus
    & at least 20 other Opels

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    Tennessean Site Supporter My location hrcollinsjr's Avatar
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    Quote Originally Posted by GoinManta View Post
    Just remember this:



    If you ever decide to get with the times
    It shore is purtee, what's it do or is it a conversation piece to polish and show off?

    Harold
    GoinManta likes this.

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    Just Some Dude in Jersey My location The Scifi Guy's Avatar
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    I don't have my exact note sheet I made up when I configured the carb, but I'm virtually certain that this from earlier in this thread is how my carb is configured:


    Venturis = 38
    Mains = 150
    Airs = 200
    Idles = 60/65
    Idle Airs = F9 or F2
    Emulsions = F16


    I don't have a lot of jets this large from my previous carb experiments, but I did order and have main jets and airs one step up and one step down from the above numbers.

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    7,000 Post Club My location wrench459's Avatar
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    Quote Originally Posted by The Scifi Guy View Post
    I don't have my exact note sheet I made up when I configured the carb, but I'm virtually certain that this from earlier in this thread is how my carb is configured:


    Venturis = 38
    Mains = 150
    Airs = 200
    Idles = 60/65
    Idle Airs = F9 or F2
    Emulsions = F16
    Ok now whats the W/B reading at cold start,idle.tip-in,cruise and WOT?

    Si vis pacem, para bellum "If you want peace, prepare for war"

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    Quote Originally Posted by The Scifi Guy View Post
    I don't have my exact note sheet I made up when I configured the carb, but I'm virtually certain that this from earlier in this thread is how my carb is configured:


    Venturis = 38
    Mains = 150
    Airs = 200
    Idles = 60/65
    Idle Airs = F9 or F2
    Emulsions = F16


    I don't have a lot of jets this large from my previous carb experiments, but I did order and have main jets and airs one step up and one step down from the above numbers.
    This is good to start with. When adjusting mix screw, forget about all theories about 1.5 or whatever turns. Just find where the engine is idling the best. If the engine speed increases over 1000 rpm during adjustment, bring it back with the throttle limiter screw (not mix screw). Do it for both barrels.
    ggl likes this.
    Old racers never die. They just go bench racing.

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    Quote Originally Posted by The Scifi Guy View Post
    For starters, could someone please describe the difference between "surging" and "hunting" as it applies to the "bog" when going off idle? These are common terms being bandied about by various online sources of info about side drafts. One means you're too rich and one means you're too lean, both cause bog-like behavior when transitioning off idle. Knowing the difference between these two behaviors and what to do about it is a talent I need to learn.
    My experience with duel 45's (on a 2.4) is two scenario's. One, you get a momentary surge followed by a bog when you accelerate. Second, you get a momentary bog followed by a surge. "Hunting" is when the engine is running at a constant rpm both above and below normal rpm so it's "hunting". "Surging" is going from normal to above normal rpm.

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    Just Some Dude in Jersey My location The Scifi Guy's Avatar
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    Quote Originally Posted by P.J. Romano View Post
    This is good to start with. When adjusting mix screw, forget about all theories about 1.5 or whatever turns. Just find where the engine is idling the best. If the engine speed increases over 1000 rpm during adjustment, bring it back with the throttle limiter screw (not mix screw). Do it for both barrels.
    Okay, I've done that, now I want to smooth out the transition from idle to acceleration and, in particular, the bog-cough-and stall if I give it too much pedal too fast.

    Suggestions?

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    Have you actually, tried the car with said setup or you are trying to be George? Joke aside, I don't remember reading that you drove your GTX yet.
    Old racers never die. They just go bench racing.

  17. #55
    ggl
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    Gut feeling says it's running lean, "sneezing" through the carb is usually a sign of lean mixture btw, and a possible cause could be the acc pump. These carbs are usually set up with one carb feeding 2 cylinders but you have one carb feeding 4 cylinders so whatever the pump is delivering is now divided by 4 rather than 2.

    Or is it working at all, could the pump jet be blocked by debris ?
    "I hate RallyBob"


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    Quote Originally Posted by The Scifi Guy View Post
    Okay, I've done that, now I want to smooth out the transition from idle to acceleration and, in particular, the bog-cough-and stall if I give it too much pedal too fast.

    Suggestions?
    How severe is it? As stated by ggl, sounds like lean is the thing. I found mine like to run a little rich or else they like to fight. The emulsions are where I made the largest step towards a better fast acceleration.
    Last edited by pinballace; 02-18-2016 at 02:31 PM.

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    Just Some Dude in Jersey My location The Scifi Guy's Avatar
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    The video below is from my first start up day. FO81 pointed out that it was likely that it was cranking with difficulty due to my diz probably being too advanced. I have since then retarded the diz and refined the idle mixture, plus I also deleted the pcv valve and am now just venting to the air. The engine now runs much smoother. The tap that you hear has diminished(maybe that hyd lifter was reluctant to pump up), but is still there. The bog that you will see is now much diminished, but is still there. At present I have fiddled with timing and mix and gotten things pretty servicable and could start the next phase of tuning it at the higher rpm levels, but the bog can cause a stall if I don't remember to sneak up on the touchy gas pedal when going off idle. The off-idle transition is what I need to smooth out before it is truly drivable.

    I'll try to take another video in warmer weather tomorrow or this weekend with the car fully warmed up, which it wasn't in the video below:


    http://api.viglink.com/api/click?for...ure%3Dyoutu.be

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    Quote Originally Posted by The Scifi Guy View Post
    The off-idle transition is what I need to smooth out before it is truly drivable.
    Give the old girl more fuel she be lean as beep. Then the transition will be much better.
    I want to see black smoke coming out the tail pipe...then start leaning her out.

    Next you'll need to check the spark plugs to see if 1&4 is running differently than 2&3.
    The Scifi Guy likes this.

    Si vis pacem, para bellum "If you want peace, prepare for war"

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    Quote Originally Posted by wrench459 View Post
    Give the old girl more fuel she be lean as beep. Then the transition will be much better.
    I want to see black smoke coming out the tail pipe...then start leaning her out.

    Next you'll need to check the spark plugs to see if 1&4 is running differently than 2&3.
    Thanks! That reminds me I need to check something on Green that I totally forgot about.

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    Just Some Dude in Jersey My location The Scifi Guy's Avatar
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    Just for the record and to assist those of you who are helping me, here is the list of side drafts jets and stuff I currently have:


    MAIN JETS

    130 (1)
    150 (4)
    155 (2)
    170 (2)
    190 (2)
    195 (2)
    200 (2)
    205 (2)

    AIR CORRECTORS

    115 (6)
    135 (2)
    140 (1)
    145 (8)
    150 (1)
    155 (2)
    160 (2)

    IDLES

    45 F8 (2)
    55 F8 (4)
    55 F9 (2)
    60 F8 (2)
    60 F9 (2)
    65 F8 (2)
    65 F9 (2)

    Miscellaneous:

    Exhaust valves (2)
    F9 Emulsions (2)


    There are more jets and stuff in my remaining other two carbs. They should be in the low ranges listed above.


    And confirmation of my exact current jetting:

    38 Venturis
    150 Mains
    200 Air Correctors
    65 F9 Idles
    F16 Emulsions


    So, guys, what combo from the list above would you suggest I try next? If I step up the size of a Main, aren't I supposed step down the size of the Air?


    Should I order some additional sizes?


    Last edited by The Scifi Guy; 02-18-2016 at 07:41 PM.

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