Distributor vacuum line to carb

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    Author Topic: Distributor vacuum line to carb  (Read 3805 times)

    Offline 73440

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    Distributor vacuum line to carb
    « on: May 24, 2017 - 08:59:44 AM »
    440 with 833 with Carter carb , 12* initial timing at idle , the distributor vacuum advance is capped at the distributor but noticed the vacuum line from the carb was not plugged, would that cause a bad burble right about at normal driving shift point , maybe 5/8 - 3/4 throttle ?  It does it in all gears? No tach to check.
    I have plugged the carb vacuum line with a bolt and will see if anything has changed.
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    67 440
    72 413 / 727
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    65 Plymouth Fury III , I sold ,was my Nana's car till 92 yo.
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    59 BelAir 283 4 door original patina
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    Offline burdar

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    Re: Distributor vacuum line to carb
    « Reply #1 on: May 24, 2017 - 09:32:50 AM »
    The vacuum advance canister on a Mopar is connected to a "timed" vacuum source.  This means that the vacuum port is "above" the throttle blades and doesn't see vacuum all the time.  With that port open(not capped) the engine should idle just fine.  As you open the throttle though, you'll have a big vacuum leak.
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    Offline cudabob496

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    Re: Distributor vacuum line to carb
    « Reply #2 on: May 24, 2017 - 10:59:14 AM »
    would think any uncapped vacuum port on a carb would affect performance
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    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline 73440

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    Re: Distributor vacuum line to carb
    « Reply #3 on: May 24, 2017 - 12:13:33 PM »
    Thank you all, I bought multiple caps the other day along with metering rods, jets , squirters, springs to make adjustments and will take her out for a drive and check.
    Would be nice if the cap would take care of the stumble , if not , got the parts to adjust.
    Logged
    67 440
    72 413 / 727
    73 Barracuda w/ 68 440
    65 Plymouth Fury III , I sold ,was my Nana's car till 92 yo.
    51 Ford F1 239 Flathead, flipped , new cab , stolen
    59 BelAir 283 4 door original patina
    01 Chevy van 420, 520 miles
    06 Crown Vic Police Interceptor
    75 HD Ironhead converted to RH shift
    73 HD Ironhead
    82 HD Ironhead
    74 Norton 850
    80 HD Shovelhead
    80 Husqvarna WR 390

    Offline Chryco Psycho

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    Re: Distributor vacuum line to carb
    « Reply #4 on: May 24, 2017 - 03:38:27 PM »
    the port on thecarb is ported vcuum so it is sourced from the venturi in the carb so it is above the throttle plates , so it should have zero effect
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    Challenger - You`ll wish You Hadn`t

    Offline 73440

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    Re: Distributor vacuum line to carb
    « Reply #5 on: May 24, 2017 - 07:55:25 PM »
    Thanks, sounds like I'll be using some of the other parts to correct the stumble.
    Logged
    67 440
    72 413 / 727
    73 Barracuda w/ 68 440
    65 Plymouth Fury III , I sold ,was my Nana's car till 92 yo.
    51 Ford F1 239 Flathead, flipped , new cab , stolen
    59 BelAir 283 4 door original patina
    01 Chevy van 420, 520 miles
    06 Crown Vic Police Interceptor
    75 HD Ironhead converted to RH shift
    73 HD Ironhead
    82 HD Ironhead
    74 Norton 850
    80 HD Shovelhead
    80 Husqvarna WR 390

    Offline jason340

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    Re: Distributor vacuum line to carb
    « Reply #6 on: May 25, 2017 - 08:18:06 AM »
    Not to hijack but why does Mopar use a ported or timed vac port instead of a constant vac below the throttle blades? Just asking.
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    Offline brasil

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    Re: Distributor vacuum line to carb
    « Reply #7 on: May 27, 2017 - 02:40:41 PM »
    emmisson reasons.  Full vacuum lets the engine run cooler. because the timing @idle is way up... I use full vacuum in my 340 ...because of the cam and the compression ratio which is very high.. the full vacuum helps to get around 22 deg @ idle  but static timing is only 10 deg.   the vacuum canister pulls 12 deg. 
    just after the engine starts
    When you use timed vacuum the engine runs hotter...so NOX is lower..  but you can´t get 22deg @ idle with a high compr. engine... the starter will not "love " this set up

    Greetings Juergen

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    Offline cudabob496

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    Re: Distributor vacuum line to carb
    « Reply #8 on: May 27, 2017 - 04:58:05 PM »
    Quote from: Chryco Psycho on May 24, 2017 - 03:38:27 PM
    the port on thecarb is ported vcuum so it is sourced from the venturi in the carb so it is above the throttle plates , so it should have zero effect
    whodda thunk?
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    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline 734406pk

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    Re: Distributor vacuum line to carb
    « Reply #9 on: May 27, 2017 - 09:18:46 PM »
    Quote:
    emmisson reasons.

     :iagree: Once you change to a performance cam, everything changes! :thumbsup:
    Logged
    1973 Challenger 440 6 pack auto 3.91 rear
    2012 Dodge Ram 3500 dually 6.7 Cummins Fleece EFI Live
    1973 Challenger 318 2bbl auto 2.73 rear 22.5 mpg RIP
    1970 Challenger TA 340 4bbl auto-Sold and sad
    1999 Dodge Ram 3500 dually 5.9 Cummins Fleece tuned VGT-sold
    1995 Kawasaki ZX1100E & still alive

    Offline xtopfuel

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    Re: Distributor vacuum line to carb
    « Reply #10 on: May 28, 2017 - 07:28:06 AM »
    I do believe you could get a stumble with 5/8 throttle as that port is open, as for idle not from a ported source
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    Offline jason340

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    Re: Distributor vacuum line to carb
    « Reply #11 on: May 28, 2017 - 09:59:22 AM »
    My 440/6 stroker with cam was set up by the engine builder to the ported vac  but it idles better and seems to run better on the full vacuum port. I am going to leave it there unless you tell me otherwise.
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    Offline 73440

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    Re: Distributor vacuum line to carb
    « Reply #12 on: May 28, 2017 - 10:05:01 AM »
    I am hoping to do a drive today to check what if anything has changed by capping the carb port.
    I appreciate all the replies and help.
    Logged
    67 440
    72 413 / 727
    73 Barracuda w/ 68 440
    65 Plymouth Fury III , I sold ,was my Nana's car till 92 yo.
    51 Ford F1 239 Flathead, flipped , new cab , stolen
    59 BelAir 283 4 door original patina
    01 Chevy van 420, 520 miles
    06 Crown Vic Police Interceptor
    75 HD Ironhead converted to RH shift
    73 HD Ironhead
    82 HD Ironhead
    74 Norton 850
    80 HD Shovelhead
    80 Husqvarna WR 390

    Offline 73440

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    • Posts: 1826
    Re: Distributor vacuum line to carb
    « Reply #13 on: May 29, 2017 - 08:55:27 PM »
    The carb port was capped today and still have the stumble , now it is time for carb adjust to eliminate the stumble.
    Logged
    67 440
    72 413 / 727
    73 Barracuda w/ 68 440
    65 Plymouth Fury III , I sold ,was my Nana's car till 92 yo.
    51 Ford F1 239 Flathead, flipped , new cab , stolen
    59 BelAir 283 4 door original patina
    01 Chevy van 420, 520 miles
    06 Crown Vic Police Interceptor
    75 HD Ironhead converted to RH shift
    73 HD Ironhead
    82 HD Ironhead
    74 Norton 850
    80 HD Shovelhead
    80 Husqvarna WR 390

    Offline Chryco Psycho

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    • 70 Challenger R/T SE 70 tube Chassis Cuda now sold
    Re: Distributor vacuum line to carb
    « Reply #14 on: May 29, 2017 - 10:28:48 PM »
    as anticipated
     check float level first if it is low that can cause a stumble .
     
     so here is the deal if you connect vacuum advance to manifold vacuum which is highest at idle or rolling down hill you get full advance with no power & it drops with rpm or power added so it work exactly opposite to the machanical advance in the dist so why would you ever want that unless you want static timing cross the powerband. With ported vacuum the advance runs the same way as the mechanical advance increasing lead time to get the fuel burnt at the peak moment as fuel dos not burn faster at higher RPM  so it needs more leadtime
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