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Re: Vacuum too low for 440 w/ MP 509 cam???
[Re: 69 Road Chicken]
#518437
11/07/09 07:37 PM
11/07/09 07:37 PM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
Just checked the manifold vacuum on my 440 with a Mopar 509 cam. I'm getting only about 5" at 1000 rpm, 4" or less at 800 rpm. This seems very low to me. I checked for vacuum leaks (carb cleaner method) but didn't find anything.
What do you guys think?
I'm concerned that my power valves may be opened up at such low vacuum levels. I'm able to turn the idle mix screws in almost all the way before killing the engine.
Just got the car this spring and have been chasing a "surging at cruise" issue since I've had it.
My timing is at 18 intial, 36 total. I've playing with this some to try in increase the vacuum level, but without any real success.
Its very possible that the PV is opening & causeing a rich mixture, this will make it hard to tune & cause even a lower reading then one would exspect from a curtain cam, i would change the PV to a 4.5 & see what the plugs look like, 18* int. isn't bad, but 22 int. 36 total would be better.
Another thing to check is, make sure you don't have too much of the transfer slots exposed on the primaries, this will also let it draw fuel because its into the main metering.
Last edited by joedust451; 11/07/09 07:40 PM.
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Re: Vacuum too low for 440 w/ MP 509 cam???
[Re: joedust451]
#518438
11/07/09 10:42 PM
11/07/09 10:42 PM
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Joined: Sep 2007
Posts: 50
Wisconsin
69 Road Chicken
OP
member
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OP
member
Joined: Sep 2007
Posts: 50
Wisconsin
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Would the Power Valve opening at idle affect the vacuum reading? Transfer slots look like small "squares" when viewed from the bottom of the carb. I think this is right. Just let the car idle for a while and check the plugs? I guess I always assumed that the idle circuit ran a bit rich and plugs would always look black after just idle. Is this incorrect? I can check this tomorrow. As you can tell, I'm not an expert at reading plugs - but I know the difference between black, tan and grey. From my old snowmobiling days, gray is the color you get when "she's running faster then she ever has" right before you melt it down  Any other opinions on the vacuum level for a 509 cam?
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Re: Vacuum too low for 440 w/ MP 509 cam???
[Re: 69 Road Chicken]
#518439
11/07/09 10:57 PM
11/07/09 10:57 PM
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Joined: Sep 2006
Posts: 692
pa
ramman16248
mopar
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mopar
Joined: Sep 2006
Posts: 692
pa
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I am running a 509 in my 440. The vaccum was too low for my power brakes. I added a vaccum canister from summit. It how geat 10-12 at idle and 15 and higher at speeds. It definately helped the power brake issue out!! I guess the .509 cam has been known for low vac.
Last edited by ramman16248; 11/07/09 10:57 PM.
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Re: Vacuum too low for 440 w/ MP 509 cam???
[Re: 69 Road Chicken]
#518442
11/08/09 03:43 AM
11/08/09 03:43 AM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
Would the Power Valve opening at idle affect the vacuum reading?
Transfer slots look like small "squares" when viewed from the bottom of the carb. I think this is right.
Just let the car idle for a while and check the plugs? I guess I always assumed that the idle circuit ran a bit rich and plugs would always look black after just idle. Is this incorrect? I can check this tomorrow. As you can tell, I'm not an expert at reading plugs - but I know the difference between black, tan and grey. From my old snowmobiling days, gray is the color you get when "she's running faster then she ever has" right before you melt it down
Any other opinions on the vacuum level for a 509 cam?
To answer some of your questions, "Yes", if a PV is opening at idle, it will affect the manifold vacuum, because its dumping excess fuel when its not needed, your spark gets week, the manifold vacuum suffers as a result.
If your plugs ARE black, then they need to be changed with a fresh set, in some instences, you may need to go through 3-4 sets of plugs getting things dialed in if your haveing an overly rich condition. You can't properly tune any engine with foiled plugs, the reason it is breaking up at higher RPMs is the fact that the plugs heat range is being interupted & there for causeing them to not fire properly, its simple really, a plug has a specific heat range, this drasticly changes as an engine is under any "load", when they are foiled in any way but not gas/oil soaked, they will fire under the lightest conditions (idles or free reving), its the plugs ability to transfer that heat.
.509s manifold vacuum, on adverage, they will useally be around 10 inches out of gear, the thing about them is there overlap & dur. @ 50, its alot considereing the lower lift, these cams do not have any advance ground into them when built like comp cams do, so when you line up the dots like alot of us do (even though we don't admit it), this can cause issues, i will be the 1st. to admit i just line up the dots, but i'm ready for what may unfold with the tuneing, & for the most part, i get them tuned nicely & they kick ass, they really like to be advanced when installed, you can set them at 106*, but 103-104* would be better, i just put alot of int. timing in them, alot of stall & gears.
I would start with getting more int. timing in it 1st., say 22*, then drop in a fresh set of plugs, install a 4.5/5.5 PV, you also could "barely" crack open the sec. butterflies to let in alittle more air, but don't get carried away doing this, it can & will cause a dead spot, if mainold vacuum still doesn't increase once all this is done, you'll need to advance the cam.
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Re: Vacuum too low for 440 w/ MP 509 cam???
[Re: 69 Road Chicken]
#518443
11/09/09 11:38 AM
11/09/09 11:38 AM
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Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem
master
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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The vacuum advance should always be unhooked till all your tuning is done. First big problem is people insist on putting it on the wrong port. needs to be on ported vacuum NOT manifold. Second even on ported as you work through idle issues with a bigger cam you may end up with the throttle plates a little two open so even on ported it may be exposed to some vacuum when it should not. Now you probably could us the cam advanced up a few degrees?? The 509's really like that. Next with vacuum unhooked and plugged start moving the timing up and playing with your idle speeds and mixtures to see if you can get it better. don't worry about total at this point you are concerned on what makes it idle better and with more vacuum. Set the in gear idle closer to 1000 than 650 a stock cam would like. Your 18 is that in nutraul or in gear??? you may find it need 22 or more in gear @ 900 to idle right. have someone in the car for in gear tests!  Play for a couple three weeks before any thought of tuning in the vacuum advance. 
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Re: Vacuum too low for 440 w/ MP 509 cam???
[Re: Mr.Yuck]
#518445
11/09/09 12:58 PM
11/09/09 12:58 PM
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Joined: Feb 2003
Posts: 12,675
Columbia, CT
moper
I Live Here
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I Live Here
Joined: Feb 2003
Posts: 12,675
Columbia, CT
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I've never had a .509 pull better than 10" out of gear. Most idle around 3-5" in gear. Drop the PV and re0tune the idle mix. It's an old design and you dont know if it was degreed and put in right, or if the rest of the engine was matched properly for it. If you can take cylinder pressure readings you can get a better idea of if there is a problem, or it's "just the way it is".
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: Vacuum too low for 440 w/ MP 509 cam???
[Re: Dodgem]
#518447
11/09/09 01:11 PM
11/09/09 01:11 PM
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Joined: Jan 2003
Posts: 5,902
Athens, Greece
Pyper70
master
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master
Joined: Jan 2003
Posts: 5,902
Athens, Greece
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I remember popping out my power valve and putting in an insert that didnt open, essentially removing the PV from the circuit and then I was able to follow my problems...Mine ended up being the cam on the right side (different problem)
Family owned 1969 Charger R/T DualQuad 440/727/GVO/3.55s
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Re: Vacuum too low for 440 w/ MP 509 cam???
[Re: 69 Road Chicken]
#518451
11/10/09 03:22 AM
11/10/09 03:22 AM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
Thanks for the advice everyone. Additional info - 4.10 gears, 4 speed. Vaccum advance is hooked up correctly to the ported vacuum, not manifold vacuum, but I will plug it during my tuning phase (I don't get good mileage anyways)
Based on what you've given me, here's my plan
1) Bump the idle up to 1000.
2) See what I get for vacuum.
3) Drop my PV's to 2 numbers below my vacuum. I'm assuming I'll be in the 3 to 3.5 range once I get the idle to 1000 (guessing 5 to 5.5 of vacuum)
4) Retune the idle mixture to get best vacuum
5) New set of plugs and check for color at this point
Stage 2 (optimize timing - which will wait until the cool whether passes next spring)
5) Up the initial timing to get best vacuum?? Not so sure on this - Am I aiming for highest vaccum while maintaining my 1000 rpm idle? Won't I get to a point where it won't want to start?
6) Recurve the distributor to get my higher initial and reasonable total (in the 36 to 38 range??). All in by ????
7) Now the fun starts - upgrade to MSD ignition and distributor. Based on all these mods, now I'm going too fast. Upgrade to front disc brakes. Now it's so fun to drive I need to upgrade the suspension. Wow, this is a viscous circle, isn't it?
Let me know if you see any problems with my initial plan.
Thanks
I see its a 4sp., so your only concern is idle, not in gear, this is a plus, the 1st. thing i would do is have the dist. recurved by someone like FBO, Don can hook you up, or, get a fully adj. unit like MSD (more $$$ though), with a heavier car like yours, all adv. in by 2800 RPMs or so, lighter cars can handle it in earlier, you may not need to go so low on the PV # once its curved & has a fresh set of plugs, i'd say a 4.5/5.0, set the idle at 1000 or 1100, it'll be much happier there., another thing that really helps is haveing a 4 corner idling system on the carb, but you can get by with 2 corner.
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