Tuning my 383

[deputycrawford]

     Unplug your vacuum advance and plug the vacuum source. Leave it that way forever. Rev you car to around 3000 rpms and set your timing at 36 degrees. That will set you total mechanical timing. Let your car idle and check your idle timing. If ist not around 18 degrees then you have to shorten you mechanical advance. Mopar Performance will have a kit through your local dealer. With that cam you will want around 16 to 18 degrees timing at idle and around 36 degrees of total mechanical timing in by 3000 rpms. I bought a new MSD distributor. That will get you where you want. It will also hook up to a stock ignition. Do it any way you want. Just get idle and advance timing in that range. Many of your problems will go away. Only then can you start your carb tuning. I also run a 383. The only difference is I run a mechanical .575 cam. I run around 20 degrees idle timing and around 38 to 40 degrees mechanical advance total. Start with timing. then carb tune. I hope that gives you some new ideas.

[Harlow]

What was your vacuum reading AFTER you changed the power valve to the 3.5? 

Around 7-8" hg from the manifold vacuum.

So if my total advance is too much or too little I have two options.
A. I have to re-curve the stock distributor's advance
B. I get an electronic conversion kit and I can just set the initial and total?
Sound right?

And no one thinks it could be the accelerator pump linkage being adjusted improperly?

[supserdave]

You really need to find out what your total advance is before you worry about anything else.........

[deputycrawford]

     Also;  7-8 inches of vacuum at idle sounds like you have too little idle advance. With that cam size, I would set it at around 16 to 18 degrees advance at idle. Then go for the mechanical advance at 38 total at around 3000.

[firefighter3931]

     Also;  7-8 inches of vacuum at idle sounds like you have too little idle advance. With that cam size, I would set it at around 16 to 18 degrees advance at idle. Then go for the mechanical advance at 38 total at around 3000.

The low idle vacuum is a product of the cam profile. That cam is very close to the MP 509 which has a lot of duration....not the beast or easiest cam to tune. 

Deputy is on the right track ; plug off the vacuum advance and bump up the base timing to 18* at idle then check your total timing. As mentioned you might need to limit the mechanical advance to 18*-20* by modifying the distributor. Big cams with lots of duration and overlap like lots of initial spark lead. 



Ron

[Harlow]

If the distributor is the root of the problem, that would make sense, because its one of the things I changed. The original distributor still works so I'm going to swap that one back in and see what happens, because It ran really good with that old one. I'll let you guys know what happens.

- Scott

[Harlow]

Alright, no total timing numbers for you yet, but I swapped that distributor back in,

Re-did the idle mix screws, they are turned out 1 1/4 for max vacuum
I had it at 15* initial

I backed it out and just did a quick bit of pedal up the driveway and it just stumbled all the way. Any time I gave it pedal it stumbled.

- Scott

[Harlow]

Alright sorry for so many posts guys, but I don't really have anyone I can ask in person so I come here for help. Could I have messed up putting the linkage back together after the rebuild? I took some pictures:

There is a piece (picture with arrow pointing at it) that can move about .5" in either direction, it doesn't seem to be touching any other pieces or riding on any cams, just sitting there. tell me what you guys think or if you see any other potential problems. Thanks for all the help so far, I'm really learning a lot.

[resq302]

Just curious but seeing that make shift throttle cable connection makes me wonder if the cable might have slipped and you are not getting the carb to open up all the way when the pedal is all the way to the floor.  I had that happen to my charger when I did some work on the throttle cable retainer bracket and did not get it back in the same spot.  Baffled me like crazy as to why the car had balls before and then after I was done swapping in the correct hold down that it couldn't get out of its own way.

Just something to consider.

[Harlow]

Is the throttle cable attached to the incorrect spot? Thats how it was when I got it and I figured that was correct. I know the spring that pulled the throttle back is incorrect, but where should the throttle cable be attached?

[resq302]

Harlow,

You have the cable in the right spot.  Just that solderless connector end makes me leary about it. 

Here is a link to where you can see some pics of my engine. http://www.dodgecharger.com/forum/index.php/topic,22311.0.html
You might be able to see where and how the correct cable goes.

Brian

[Harlow]

Thanks for the pictures Brian. Anyone have any idea about that piece of linkage?

[Chryco Psycho]

the extra arm is for ford kickdown it is not used on Mopars