Re: amount of vacum @idle ?
[Re: mopar0723]
#912981
01/24/11 06:31 PM
01/24/11 06:31 PM
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Joined: Oct 2003
Posts: 996 Queens, New York
Harley
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Quote:
1970 440+6 engine bored 030 stock spec cam 292 duration 590 lift how much vacum should I have at idle say 800 rpm /vacum gauge hooked to rear of intake.
292/590 lift is far from stock. If that is the cam you are running, i would think more like 12 to 14 inches of vacum.
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Re: amount of vacum @idle ?
[Re: mopar0723]
#912983
01/24/11 06:45 PM
01/24/11 06:45 PM
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Joined: Oct 2007
Posts: 3,911 Oregon
hooziewhatsit
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What's your initial timing at?
If you ever find yourself in a fair fight, your tactics suck.
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Re: amount of vacum @idle ?
[Re: mopar0723]
#912985
01/24/11 07:09 PM
01/24/11 07:09 PM
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Joined: Jan 2003
Posts: 2,006 s. e. pa.
calrobb2000
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hi 9 in with that cam no more prob? idle speed for a six pack is 900 rpm ! what is your actual comp ratio or cranking compression psi ?? ![](/ubbthreads/images/graemlins/drive.gif)
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Re: amount of vacum @idle ?
[Re: mopar0723]
#912989
01/24/11 08:06 PM
01/24/11 08:06 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Lincoln Nebraska
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Quote:
if set @ 800 fluctuates between 780 - 810 normal ?
Actually yes as I forgot that you have a cam. It MAY need a higher idle speed to stabilize. EDIT after (re) reading I dont think it's a dist prob. I would set the (initial)timing via the vac gauge method then shorten the slots to get 36-38 total then play w the springs (more on that later) then dial in the vac adv (more on that later). You will need to find the idle speed for that cam that is stable (maybe higher than 800) and I am not a 6 pack guy but they (the carbs) MAY or may not need mods for a wild cam
Last edited by RapidRobert; 01/24/11 08:19 PM.
live every 24 hour block of time like it's your last day on earth
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Re: amount of vacum @idle ?
[Re: mopar0723]
#912991
01/24/11 09:02 PM
01/24/11 09:02 PM
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Joined: Feb 2005
Posts: 4,324 Prospect, PA
BSB67
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Quote:
1970 440+6 engine bored 030 stock spec cam 292 duration 590 lift how much vacum should I have at idle say 800 rpm /vacum gauge hooked to rear of intake.
Your statements regarding the cam do not make sense. There is no stock cam with specs anywhere near what you've posted.
Is it possible that it is a Mopar 292/509 cam?
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Re: amount of vacum @idle ?
[Re: mopar0723]
#912994
01/24/11 09:22 PM
01/24/11 09:22 PM
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Joined: Jul 2006
Posts: 4,179 California
mickm
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Quote:
Yea I can not set car @ 900 rpm, where it probably should be, it is a 4 speed. as soon as I turn idle up and get to about 870-880 it just takes off to the 1050-1150 as stated above and stays there, then have to loosen idle screw to get it back down, only does this if vac adv hose hooked up,won't do this if I plug, but I want it hooked up and it all to work the way it is supposed to. I do not know what else to try before buying a new distibutor.
get a vacuum pump gauge on the vacuum advance. disconnect the hose at the carb, and plug the gauge in there. take off the distributor cap, and see at what level of vacuum the plate starts to rotate. sounds like it is set very low, and is advancing as soon as you hit the 800 rpm range or so.
i don't know about the older distributors, but with the newer ones you can stick a small allen wrench in the hole on the vacuum advance canister where the hose plugs into. with that, you can loosen or tighten the springs on the vacuum advance, so it comes in with more/less vacuum, as needed by your situation.
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Re: amount of vacum @idle ?
[Re: mopar0723]
#912995
01/24/11 09:30 PM
01/24/11 09:30 PM
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Joined: Jan 2003
Posts: 1,770 Windsor, ON, Canada
Diplomat360
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Quote:
Yea I can not set car @ 900 rpm, where it probably should be, it is a 4 speed. as soon as I turn idle up and get to about 870-880 it just takes off to the 1050-1150 as stated above and stays there, then have to loosen idle screw to get it back down, only does this if vac adv hose hooked up,won't do this if I plug, but I want it hooked up and it all to work the way it is supposed to. I do not know what else to try before buying a new distibutor.
To me that sounds like a vacuum can adjusted with way too little tension...that means it'll come on quicker...you may be getting some interaction between the vac can and the distributor mechanical advance. Namely, the vac can kicks in...the idle speed jumps up, the dist goes into the mech advance curve...etc....the dead giveaways is that this does not happen with the vac can disconnected.
Toss in an alan wrench into the nipple and tighten it up...so that it comes on at a higher vacuum signal.
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Re: amount of vacum @idle ?
[Re: mopar0723]
#912997
01/24/11 09:50 PM
01/24/11 09:50 PM
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Joined: Feb 2005
Posts: 4,324 Prospect, PA
BSB67
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Quote:
yes you Are right I typed in the wrong numbers that is the cam in the motor 292/509
This is a big cam. Add the six pac, low compression and 10 degrees initial timing and 8" sounds right. Although I have not had this combination myself.
Personnally, I would skip the vacuum advance for now, it is just one more variable. You can put it back later.
Get your initial timing to be 20 degrees and steady (not advancing) to at least 1200 rpm. Then check for vacuum leaks at the carbs and intake manifold. Then use a vacuum gauge to adjust each carb.
That will get you started.
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Re: amount of vacum @idle ?
[Re: BSB67]
#912999
01/24/11 11:26 PM
01/24/11 11:26 PM
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Joined: Jan 2007
Posts: 153 Wpg, Mb, Canada
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With that cam you should have between 18-20 degrees initial. it's 248@50With the vacuum advance disconnected (hose plugged). Connect a vacuum gauge to the manifold and advance the initial timing to max vacuum less 1". So add advance, check vacuum, you'll likely need to reduce the RPM via carburator as more advance will increase RPM. Keep adding timing and maintain your desired RPM (900-1000) until the vacuum doesn't increase. Back the timing down 1" of vacuum and that what your initial should be set to. If you find the starter dragging you may need to take out some timing. Your total should be around 36, your initial is ~18-20 so you'll need to weld and file the distributor slots for 16 degrees mechanical advance (or purchase from FBO an adv plate limiter). You likely get 12-14 inches of vacuum. For the rpm not returning at idle, that could be the distributor, have you inspected it (remove the plate and take a look). Do the weights move freely?. Find someone with a distributor machine to set your mech advance, advance curve and check phasing. I had the same cam in 440-6pak. Had Liteweight setup the carbs, there are adjustment screws under lead plugs in the outboard carbs that made a difference. Good luck
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Re: amount of vacum @idle ?
[Re: mopar0723]
#913000
01/24/11 11:35 PM
01/24/11 11:35 PM
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Joined: Jan 2003
Posts: 5,450 So Cal
Sinitro
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I have a very similar setup and cam.. The vacuum is low.. Mine is about 8 inches The Mopar HP distributor has 20 degrees (@ the crank) and 15 degrees initial making a total timing of 35 degrees. And my idle speed is about 1050 RPM, except my carb is a 770 holley. Just my $0.02.. ![](/ubbthreads/images/graemlins/wink.gif)
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Re: amount of vacum @idle ?
[Re: mopar0723]
#913001
01/26/11 02:44 AM
01/26/11 02:44 AM
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Joined: Jan 2003
Posts: 2,006 s. e. pa.
calrobb2000
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hi where are you connecting the vac advance to ? it must be hooked to the pas side metal tube on the center carb metering block . a wrong connection could be the cause if it is returning to idle when not hooked up ! ![](/ubbthreads/images/graemlins/drive.gif)
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Re: amount of vacum @idle ?
[Re: Dougsmopars]
#913002
01/26/11 09:17 AM
01/26/11 09:17 AM
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Joined: Feb 2005
Posts: 28,312 Cincinnati, Ohio
Challenger 1
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Quote:
10 degrees timing is not enough. As memtioned bump it up to 20, bring it up as high as possible with no ping and no hard start hot. Mine likes 22 degree. Recurve the dizzy to keep total advance to 38.
![](/ubbthreads/images/graemlins/iagree.gif)
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