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Discussion Starter · #1 ·
Weeelllp,

I've completed renovated my RC. Everything under the hood, brand new. However, before I install the final component, MSD, I need to get this damn problem ironed out.

my RC had major stuttering problems whenever I start it, or get down on the gas pedal, it would hesitate before taking off, kind of like a stutter step/stutter-all out run.

My timing mark under the hood says to dial in 16 degrees advance. So I set with my timing light and now it's a lot better, but I still have small stutter issues, and starting issues. Is this normal? do I need to adjust my vac advance?

if I use the non-emissions side of my edelbrock carb it stutters, if I use the emissions side (the side with a constant vac, even at idle) it doesn't stutter so much, but after I'm warmed up it has detonation problems...

do I need to just adjust the vac advance, or do I need to adjust timing... (brand new distributor just installed.)

Chief
 

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Fitst, connect your distributor to the ported vacuum connection on the carburetor. You do not want full time vacuum advance. Do I understand you correctly, that you set your initial timing (with engine idling, vacuum advance disconnected and plugged, timing light connected to #1 cylinder) to 16° BTDC? That sounds pretty advanced to me, but then I am a bit retarded ;). What year is your truck? What engine?
First, get your timing straightened out, then, if it still sputters when you stomp on it, it probably needs more accellerator pump shot.
 

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Leave the vac advance disconnected and plugged until you find the bogging/sputtering problem. With it d/c, reset your initial timing and re-tune the carb. Once everything runs well w/o vac advance, hook the vac advance up and dial it in. Vac advance is one of the very last things to get hooked up and dialed in as it is basically a mileage saving device for part-throttle cruise conditions, and not much else.

-SM
 

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Discussion Starter · #4 ·
Okay, when I say the 16 btc, I referenced my haynes manual and it says check the sticker under the hood. The sticker says 16btc. this setting was dialed in without vac hooked up... after dialed in, I'm still suffering sputtering pedal stomps... however, I can say I had the engine dialed into 0btc, and MAN-O-MAN was that way retarded... the hesitation was pronounced even cruising at 60 mph... it's not noticeble at 16btc when cruising at 60, I punch it, and it rocks.... but during idle, and initial start, it's still existant. One thing to remember is that my ignition is the last, and only device on the truck still factory... minus the distributor.. the vehicle was originally built with emisions... so the under-hood sticker is possibly wrong, however.... it's closer to right than 0btc. Also, I did swap from 318 to 360. bored .40 over... dunno how much that maybe relevant but I do enjoy pluggin' my accomplishments whenever possible. =)

Chief
 

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just a personal note: i have never seen a 360 that is suppose to be 16 advanced. seen 318s that way. Most i have ever seen on a 360 is 8BTC.
just a little "my experience" info. take it for what it is worth.
 

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guess i am used to dealing with the 70s stuff.

what year is the 360 from?
 

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Discussion Starter · #8 ·
well... this is true... my RC was originally a 318... so maybe I need to retard it a little bit... but i got a new problem anyway now... I started adjusting my vacuum advance all around on the distributor, and now it's sputtering black crap out the exhaust again... just like it did whenever I first set the damn thing up with the new distributor... I dunno what the hell I'm doin' wrong... maybe I shouldn't have screwed with the adjustable vac advance.. which way retards the advaance and which way advances it... clockwise or counter-clockwise... I needa figure out how to get this sucker back on track... once I can get it to stop spitting black shit out the exhaust I'll set it down to 8btc, and we'll go from there.
Chief
 

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Sounds like there might be a problem with that distributor. You're using a carb and you mention a vacuum connection on you distributor so it doesn't sound like a computer version disty. You should be shooting for somewhere around 32 to 38 degrees of total advance at or above 3000 rpm. This is measured with the vacuum hose disconnected from the distributor (plug the line for this). Now at low idle (600 rpm) the centrifical advance should not be active and the setting at this rpm is usually 8 degrees BTDC. If you achieve these settings it should have a decent idle and run GREAT at 2000 rpm and above. The vacuum advance should add about 10 drgrees at idle or cruise. That is when the engine vacuum is at it's maximum. If the vacum advance is working properly you will see 18 to 20 degrees BTDC at idle. This extra advance smooths the idleout and makes for quicker 'off-idle' throttle response. Check your settings and if you can't achieve the 8 degrees at idle (no vac) and 32 to 38 degrees at 3000 rpm (no vac) I'd remove the dist and check springs and bearings.. they do need maint too.
Also the vacuum advance on most distributors are adjutable. There is an allen headed adjuster accessable through the vacuum hose fitting. I adjusts how soon the vac advance engages. I like to adjust this so it doesn't quite reach max vac advance at idle. That way the vac advance will drop off the moment you touch the throttle. If the vacuum advance is too sensitive it will not drop our during acceleration and you will experience detonation.
I always run my vacuum advance from full manifold vacuum but this is where a lot of debates start. Reducing the sensitivity of the vacuum pot makes it respond properly for a non-emissioned engine.
ported vacuum or manifold vacuum, I hope this helps at least a little!
Good Luck!
Bruce
 

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Well, I 've run it both ways, and there should be NO vac adv at idle if you are using ported vac...only during cruise. If you have vac adv in at idle, you WILL have detonation during cruising if your engine pulls good vacuum.

Dodge vac adv canisters typically give between 14 & 18 deg adv, and if you have 10 of it in during idle, you will have all of it in during cruise.

if you use manifold vac, you will have to retune the carb and idle settings.
 

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Discussion Starter · #11 ·
Excellent advice my friends.... but how do I adjust the advance on the dist with the allen head? is it all in clockwise? or counterclockwise? where do I begin with this as I have fooled heavily with the distro' now and can't tell where the f' it's at... do I just tighten it down all the way (clockwise) than work backward from there???

Chief
 

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i will see if i can find a back issue of mopar action i have that talked about this. Hopefully the wife didnt throw it out (REALLY bad habit of hers)
 

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The best thing to do would be to turn the adv all the way in OR out, and work from there. You won't change how much adv you get, only the vac at which it starts coming in.

I turned mine all the way in, and checked to see what the timing was with the vac adv connected to my vac pump. This way, you can adv the timing all the way and not have to rev the engine, or worry about mech adv coming in. I wrote down the amount of adv and the vac at which it started coming in and at full adv. I then turned it out 1/2 turn, and did the same thing again.

Doing it this way, you will know exactly how much vac adv you get for a given amount of vac, both when it starts coming in and when it is fully in.
 

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Per the MOPAR engine build manual:

turn clockwise 1/2 turn (180 degrees) to decrease 2-3 degrees.
 

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hmmm...from what I have found out by testing the way I did, the amount of timing is not adjustable...just the vac at which it comes in.

that 1/2 turn MAY change the point at which it comes in enough to give you 2-3 deg less adv at THAT particular vac level.
 

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TheRamChargerMan said:
hmmm...from what I have found out by testing the way I did, the amount of timing is not adjustable...just the vac at which it comes in.
That has been my experience as well.

-SM
 

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TheRamChargerMan said:
hmmm...from what I have found out by testing the way I did, the amount of timing is not adjustable...just the vac at which it comes in.

that 1/2 turn MAY change the point at which it comes in enough to give you 2-3 deg less adv at THAT particular vac level.
I think they are assuming ~15 inches. During cruise, you will get a given vacuum. When you accelerate the vacuum drops as does the vacuum advance. So this should be adjusted to set your total advance at 2600 RPM or better.
 
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