Hi guys, I'm new here. I've got a 69 383 Charger that's been giving me a headache for a little while now. Since I changed my intake and carb from a 2 bbl to a 4bbl setup, I've had hiccups and bogging from idle on takeoff. Once rolling on the highway, she's fine. I also noticed last week when I did my last oil change before storage for the winter, the aircleaner lid and airfilter were full of black soot. Probably from all the hiccuping. Running to rich? Not sure.
What's my problem?
- Thread starter Mozeby
- Start date
BootHead
Well-known member
So what intake and carb are you running? From the hip, barring some carb tuning, I'm guessing she'd respond to the mechanical advance coming in earlier.
Some more particulars would help diagnose from afar.. bone stock? some modifications?
Welcome to here, you'll get some fine advice soon.
Some more particulars would help diagnose from afar.. bone stock? some modifications?
Welcome to here, you'll get some fine advice soon.
Dr.Jass
Pastor of Muppets
Knowing what carb you're using would be a big help, but right off the bat I'm going to guess you've got a vacuum leak at the intake gasket. This sounds exactly like what my friend's 440 Satellite was doing, and it turned out he tried to re-use the intake gasket after changing the intake.
My mantra for big-block intake gaskets goes like this: Always use a new "turkey pan" gasket, never use the paper gasket facings that come with it. I spray both the head and intake sides of the turkey pan with Permatex High-Tack spray gasket sealer, and nothing else. In place of the High Tack spray, one could use Permatex Aviation Form-A-Gasket, but it's slower and messier. No one, to my knowledge, makes an RTV (silicone) sealant that will hold up to fuel. The only place silicone is used is across the front and rear rails, and only to the corners where the heads meet the block; there I use Permatex Ultra Black or Right Stuff.
My mantra for big-block intake gaskets goes like this: Always use a new "turkey pan" gasket, never use the paper gasket facings that come with it. I spray both the head and intake sides of the turkey pan with Permatex High-Tack spray gasket sealer, and nothing else. In place of the High Tack spray, one could use Permatex Aviation Form-A-Gasket, but it's slower and messier. No one, to my knowledge, makes an RTV (silicone) sealant that will hold up to fuel. The only place silicone is used is across the front and rear rails, and only to the corners where the heads meet the block; there I use Permatex Ultra Black or Right Stuff.
Tex-par
Well-known member
Doc has a good point about the vacuum leak. shoot some carb cleaner or starting fluid around the edges of the intake and see if the RPMs come up from sucking it in around the edges of the intake. if not I still would see if the accelerator is too lean and when you open the throttle you go to lean for just a moment . You could also need to replace the little plastic cam the pump arm rides on for a faster ramp one.
BootHead
Well-known member
"horrendous timing error" hmm Did you hook up the vacuum advance? where?
according to http://www.holley.com/data/Products/Technical/199R10219-3.pdf it should go to the port above the idle adjustment screw on the right side.
according to http://www.holley.com/data/Products/Technical/199R10219-3.pdf it should go to the port above the idle adjustment screw on the right side.
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Dr.Jass
Pastor of Muppets
In my experience, when a B/RB engine is suckin' air from the intake gasket, it's from underneath most of the time. In that case, the carb-spray test won't work. However, under hard acceleration letting off the accelerator quickly will usually produce a huff of blue out the exhaust from the vacuum spike (the leak will suck oil vapor from the crankcase/lifter valley). That of course could be other things as well, but if the engine wasn't doing it previously you have your culprit. Another test to try: with the air cleaner off and the engine warm (choke all the way open), slowly lower your hand down over the choke tower. If, as your hand gets closer to closing off the choke tower, the engine picks up speed you've got a vacuum leak. If it doesn't do it noticeably at idle, try cranking the idle up to say 1500RPM and try it again.
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Dr.Jass
Pastor of Muppets
For the record, I don't think it's the carb. A Holley Street Avenger 670 is not going to be lean on any circuit on a stock 383-2V longblock... unless it got crap in the fuel right away. I'm sticking with my original diagnosis--vacuum leak or timing problem. Assuming the distributor didn't come out during the intake swap, it precludes timing as a problem since it ran OK with the 2-barrel. The vacuum advance being on the wrong port would only screw with the idle--sometimes it'd be 750RPM, others it would be well over 1000RPM. It would not affect driveability whatsoever as the ported vacuum source to which it should be connected is like an on-off switch, it's not a variable vacuum source.
The distributor was changed when I changed over to a MP electronic ignition kit. All 3 things were changed together - Carb, Intake, Ingnition. With the stock setup it didn't run too hot either because the carb needed a rebuild, but it never hiccuped and popped the way it did after the swap.
patrick
Active member
Did you use a new valley pan? And/or is your intake and carb new? It sounds like the intake is sucking air out of the valley, along with exhaust soot from the head cross overs.
BootHead
Well-known member
but if its hooked to the full manifold vacuum port it would dump the vacuum advance in situations as described "I've had hiccups and bogging from idle on takeoff" Mash the gas, the vacuum drops, and before the mechanical advance is even thinking about coming in it in effect retards the timing, because at idle it is advanced as far as the limit is set via the allen screw inside the vacuum motor(I forgot the range of adjustment)
Dr.Jass
Pastor of Muppets
Nope, it doesn't work that way. On the ported vacuum, the second the throttle comes off idle, the vacuum canister pulls in full vacuum. It's not a variable-rate thing--like I said, it's an on/off switch. Connecting the spark vacuum to the wrong port absolutely, positively cannot cause the problems he's having. If you don't believe me, get two vacuum gauges and connect one to full manifold vacuum, and tee the other in with your ported spark to the distributor. The second you move the accelerator pedal, no matter under what load you put it the two gauges will have identical readings. The only difference between the two sources is that the ported spark opening is above the throttle plates, and the full manifold vacuum is below them. Once the throttle plate is opened even the slightest bit, the vacuum is equalized above and below the throttle plates and they will read the same on a gauge.
The only thing you'll get with the vacuum advance hooked to the wrong port is an erratic idle. I added a ported vacuum to the lean-burn ThermoQuad that was on my Charger prior to the Six Pack, and the only gain was a consistent idle (that's why I did it).
Knowing it did this prior to the swap is helpful--I had not mentioned the timing-chain thing because I thought it ran fine previously. 68R/T has a good point there; a timing-set swap is probably in order. Use only a double-row roller set; done flat-rate style it's a sub-2-hour-job. You don't even have to remove the alternator on a big-block... just remove the adjustment bracket and swing it out of the way.
Though I still think it's an intake leak, I'd probably replace the timing set. With the right incentive, I've done both (on my 440) in less than two hours. Come to think of it, I also swapped the cam when I did that. The B/RB Chrysler has got to be the all-time easiest engine to service.
The only thing you'll get with the vacuum advance hooked to the wrong port is an erratic idle. I added a ported vacuum to the lean-burn ThermoQuad that was on my Charger prior to the Six Pack, and the only gain was a consistent idle (that's why I did it).
Knowing it did this prior to the swap is helpful--I had not mentioned the timing-chain thing because I thought it ran fine previously. 68R/T has a good point there; a timing-set swap is probably in order. Use only a double-row roller set; done flat-rate style it's a sub-2-hour-job. You don't even have to remove the alternator on a big-block... just remove the adjustment bracket and swing it out of the way.
Though I still think it's an intake leak, I'd probably replace the timing set. With the right incentive, I've done both (on my 440) in less than two hours. Come to think of it, I also swapped the cam when I did that. The B/RB Chrysler has got to be the all-time easiest engine to service.