Maiden voyage after 9 years...but poor 383 performance?

[Mfr426]

Hello all, I finally got my 69 on the road after 9.5 years of painstaking restoration. I've had a blast driving it over the last 4 days even though the motor is sluggish. The motor is a 71 383, mopar performance RR cam (NOT the street hemi), factory HP Ex. manifolds, Carter AVS (rebuilt a few months ago), factory 4v intake, windage tray, new Carter fuel pump, new rings, etc.

Car idles fine, oil pressure is good and temp is fine but when I accelerate while driving I get very sluggish response and it breaks up. It hesitates and stumbles and I have to really lay into the pedal and still get only OK response. When I finally lay off the pedal I get a good amount of black smoke out of the tailpipes and the car breaks up power wise. I pulled 2 of the plugs and have black carbon fouling from the overly rich mixture I presume. They are new NGK plugs too.

I double checked the accel pump rod height and that's right on. Timing is at 8 BTDC. I've checked cap and rotor and they are fine. Point gap was checked too.

I'm half tempted to buy a new Edelbrock AVS as I've had no luck with the few carbs that I've tried to use.

Anyone have any comments or suggestions on what I should be looking for? Anyone think that buying a new carb is a good investment?

[dodge freak]

Yes a new carb  is nice, If you know alot about them you MIGHT save a few dollars by getting one off e-bay, but somebody may have messed around with it and then gave up with it. I still can't understand why they cost as much as they do  Its a rip off I think , Maybe if  china were to sell them the price would go way down. Its too bad you already had the old one rebuilt, I hate to see you buy a new one and still have the same problem. It idles good well that means intake is not leaking and the spark plugs are all firring right.  A brand new carb maybe the answer.

[Mfr426]

Thanks Dodge guy. I agree why are the carbs so damm expensive? I can slip many things by my wife cash wise but I've already blown the budget for this month.

I did get a bunch of carbs on ebay but like you said someone may have messed around with them. I'll never know unless I replace them...

Can you say Cha Ching $$$ ?

[moparjohn]

Milke,
First off congrats on hitting the streets! feels great don't it? I also rebuilt my original carb with less than good results- it ran fine just no go. I then tryed a 600 eddy, ran better no go and a restart issue when hot, changed to an 800 eddy and got even better respose but no improvement with hot stars (even using a carb spacer for it) I finnally was talked ino a Holley and man what a difference. It runs the best it ever has with it, no hot start problems at all. The only thing is you need a carb spacer for clearance on the trottle linkage, you need to relocate the coil, and need a dual feed fuel line. I got the fuel line and coil bracket from Fabulous Fabrications (seen in MCG) and for a carb Herbs had the best price I could find .John

[deputycrawford]

You said your timing was 8 degrees and you have a larger than stock cam. Get us all of your cam specs and i'll get you in the timing range. Without knowing your cam specs, I can already tell you to advance it to, at least, 12 degrees and see how much it gets better. It will get better. My 383 has a .545 lift cam in it and it likes to idle at 20 degrees. Ask Mopar John, he's driven it. It also likes around 36 to 38 dregrees timing by 2500 RPM's. You might need to check the whole distributor out first. Then lean out your jetting. That thing might come on like a light switch. Let us know how its going. Oh, by the way, I run a Barry Grant Mighty Demon. I will never buy anything but Demons again. I can not tell you the orgasmic feeling that car gives you when you floor it. Its perfect.

[Mfr426]

Hey Deputy, the cam is from Mopar Performance from about 8 years ago. It's kit number DCC-4452783. It was listed as "Factory Muscle Car Kit" for 383 Magnum/Commando/440 engines. They dont make it anymore I dont think. The specs are:

268/248 Duration
450/458 Lift

Does this help?

Thanks for any more guidance. If I can keep this AVS I'd sure like to after all the time I put into it for restoration.

Mike R

[deputycrawford]

Ok, the cam info helps. You lobe center should be somewhere between 110 and 115 so the 12 degrees timing should be fine. Remember to check the total mechanical timing by pillung the vacum hose and plugging it. your total timing should bre around 34 degrees and be there by 3000 rpms at the latest. Go from there Leave the carb until you get the timing in the ball park. 8 degrees is WAY off in my opinion. You might even try 14 degrees at idle. Just be careful of spark knock. If there is some at 14 you will have to back it back down to 12 but you could be fine at 14. Please keep us informed. Oh, and Chryco and Firefighter are engine builders. They could help a whole lot more.

[dodge freak]

It might not be the carb. Its kind of odd you have all these bad carbs. Just that idles fine gets me. You should put a vacuum gauge on it, see if the needle is steady. If its jumping around do a compression test.

[Mfr426]

Thanks Guys, I'm going to try to bump the timing to 12 degrees at idle and put the AVS back on to see if the timing helps. I put on an old AFB the other night to see the problem followed the carb or the motor and it followed the motor. If the timing is/was the issue then it would explain why I replaced the carb several times and had no improvement.

I'll do the vacuum test and compression if bumping the timing does not work. The motor had good compression across all cylinders and blows no blue/white smoke so I hope that is NOT the case.

If the timing is not advanced enough I'd be dumping fuel into the combustion chamber before it could fire causing it to be SUPER rich correct (please say yes so I can explain the black soot in my tailpipes and the black cloud on acceleration).

Thanks all!

Mike

[firefighter3931]

If the timing is not advanced enough I'd be dumping fuel into the combustion chamber before it could fire causing it to be SUPER rich correct (please say yes so I can explain the black soot in my tailpipes and the black cloud on acceleration).

Thanks all!

Mike

Mike you're on the right path. Retarded timing causes the fuel to burn too late....in the header/ex. manifold. If the timing is "right" it will burn in the combustion chamber. The black soot in your tailpipes means that it's jetted to rich. Once you get the timing sorted out take it for a spin and pull a few plugs to check for color. Tan/light brown is what you're looking for. Black/charcoal is too rich....white/light grey is too lean.

Ron

[dodge freak]

Boy I am not sure. What is your timing all the way out. I mean total timing thats is what matters. Maybe the advance is rusted up in the dist., if it is then checking it idle does not tell you much. Rev that motor and see if the timing advances. Disconnect the vacuum advance if you have one. The timing should keep going up until you hit 2500-4000 rpms. Not sure what springs are in it. If the timing does not move, fix that problem. The advance is under the pick up plate. If it does move set it so you have around 37 degrees, might not be perfect but good enough for it to run fine. If you timing is fine, and the compression test is at least 130 psi  then I would think it is the carb. You might get 150, 140 ,155, 130 on the compression test. That should be ok, not prefect again but it should run ok. Only thing else I can think of is the plug wires, but those are new, right?

[Mfr426]

Thanks guys, it's like carb and timing 101 here. Seeing the black smoke does not bother me.

When I time it I pull the vacuum line and plug it. I dial in the knob on the light for 8 degrees and then time it to 0 degrees on the scale on the timing cover. I'm sure it does advance as the RPMs go up but I'll need to check that again. I dont have a tach so I cant tell when I'm at 2500 RPM. I cant believe I dont have a tach for CH***T sakes...

Plug wires are new OEM style (date coded). Plugs are new NGK. Dist was a "Frank Mitchell Special" rebuilt from a few years ago. I have sevearl things to check now. Thanks guys.

I'll post as I check off possible causes.

Thanks again!

[dodge freak]

Black smoke might not bother you but it should not do that. That is why it won't run right. If you can see it in the rearview mirror its way too much. The plugs foul out you you get a miss. Maybe its the intake gasket or the intak is leaking and sucking up engine oil.That has happen to me, I would think it be ok wide open. I am sorry but not being there makes it too hard to solve, Good Luck.

[Mfr426]

Believe me, after 10 years of restoration of this car a carb/timing/engine issue is nothing. If you would have seen the work that I had to do to get here you'd agree that this is almost a pleasure!

[Mfr426]

Well guys, I did some more testing and I must say I'm a bit sick to my stomach. I pulled the AVS carb off last night and double checked some of the adjustments. I bolted it on today at lunch and took her out. She ran just as crappy as before! It still blew smoke and sputtered on accelleration. I even bumped up the timing to 12 degrees just to try it and it still run poorly.

So, I then put a vacuum guage on the line at the base of carb that goes to the vacuum advance on my carb. My vacuum was steady at about 10 degrees. From what I read that means either bad timing or poor compression. I sure as hell hope that my recently redone motor has good compression. I'll be pissed as hell if I have to pull out my motor after all of this.

Tonight I am going to pull all plugs, check them for gap and wear and check the plug wires to make sure I have all to the correct plugs. I'll then check the ignition gap and finally compression. I have a pit in my stomach as I think about this. Could this cam be in wrong? It was keyed to only go on one way and the marks all lined up? Could the motor have poor rings? Will mike hook a tailpipe to the inside of his newly restored Charger and just go to sleep?

I'm feeling like I want to puke. Oh boy...

[mikepmcs]

Think good compression, good compression, good compression.  I'm keeping my fingers crossed for you!!!

[dodge freak]

How big is your cam? I mean some cams have only 10 degrees at idle. Does it go up when you rev it up? If its running rough it might just be show lower vacuum until it smooths out. I just wonder if it was jump around like a bad valve would cause. Too bad you aren't here in Detroit I would bolt my carb. on for you.

[Mfr426]

Here are the specs of my cam...

The cam is from Mopar Performance from about 8 years ago. It's kit number DCC-4452783. It was listed as "Factory Muscle Car Kit" for 383 Magnum/Commando/440 engines. They dont make it anymore I dont think. The specs are:

268/248 Duration
450/458 Lift

Honestly I didnt check to see if the vacuum moved all around as I was too sick to do anything else 

Thanks Mike, think positively!!!

[71charger_fan]

In my experience the B engines like more total timing than the RB engines. My 400 is at 50 degrees total and runs great.

[deputycrawford]

You're doing fine. Don't jump ahead of yourself. 10 inches of vacum at idle with that small of a cam is telling me you have something wrong that could possibly fixed easily. Get a propane torch of some sort. Do not light it, just turn on the fuel flow. while the engine is idling, slowly move the torch around the carb base gasket, the intake gaskets and the intake valley pan area. If the idle increases in a certain area then you have a vacum leak there.  Run the unlit torch around anything that has vacum. If you don't find anything then ask your engine builider where, or if, the cam was degreed. There are many things that can be tweaked. Yes, check your compression so you can tell Cryco or Firefighter what your cylinder pressures are but you might have some adjustments out of wack. It will be very satisfying when you learn about many of the systems of your engine and get it running right. It will give you confidence for future problems. You might even see if you can get an engine builder to put a piston stop in your cylinder to check for true Top Dead Center. Then check you balancer to see if is hasn't slipped. Learn about all of your systems and check back with us.

[deputycrawford]

You know, I just read back through all the posts. Also try to jet the carb down a good four to six sizes and see if it helps. I'll bet it does. Timing helps in the fine tune but You need a major change and the main jets might help quite a bit.

[Mfr426]

Hey Deputy (and all) thanks for the tips. Tonigth I'll have the honey help me check all compression. As soon as I get the numbers I'll post.

I wish this dam work thing didnt disrupt my car time - boy it's annoying!

:- )

[deputycrawford]

Work is just the break we take from our cars.    I would also take the main jets out and see what size they are. If timing didn't make that much of a difference then start jetting down. Maybe four or five sizes to start. Of course, I mentioned the total timing before but didn't emphasize it enough. Dodge freak mentioned it, the total mechanical timing should be around 34ish degrees. Check to see your distributor is working properly. It should only take a second to check. Pull your vacum advance hose and plug it. Get a dial timing light and rev the engine to around 3000. You only have to be closse for a check. Turn on the light and turn the dial until it reads 0 degrees on the balancer. Check the dial and it will tell you where the total timing is. Put the vacum hose back on and check the timing again at around 3000. It should read somewhere around 55 degrees. Then you can check your distributor off the list. You'll get there. The list can only get shorter.

[Mfr426]

OK...just tested compression and it's 120psi across ALL cylinders! I'll take that for a 71 383 2v. At this point I'm pulling the trigger on a newly remanufactured Carter 600 CFM AVS from Jegs. I have NO cofidence in the carb that I have and dont want to waste any more time on it.

Thanks Deputy (and all others). I'll report when I put the carb on.

Wish me luck!

[dodge freak]

And if its not it then we know its not it. That leaves the intake manifold and gasket, maybe its crack or the gasket leaks bad and is sucking up motor oil, or its in your ignition. But if it is your carb, good chance, then you should give a very nice call to the guy who rebuilt your carb and great feedback to those e-bay sellers. It is hard to believe you keep getting a bad carb though.