Stock 383 4bbl distributor curve

[Force Fed Mopar]

Trying to figure out my 383, took the distributor apart and found a L15.5 governor and a 13L vacuum advance pod. Does that sound right? Engine seems to take a lot of initial advance to crank up and rev properly, but when you hook up the vacuum advance can, it dies.

IIRC you double the numbers on the distributor parts to get your timing numbers. As the vac adv pod says 13, that's 26 degrees of vacuum advance, which I'm guessing is why it dies when I hook it to manifold vacuum. If I hook it to a ported vacuum port, it won't rev just misses bad and tries to die.

Do I need to set the initial timing real low, or is it a case of someone mis-matching parts? Once warmed up fully it'll rev decent w/ the vacuum advance disconnected.

 

[Red63440]

What is your timing set at now? Are there any modifications to the engine?

 

[Force Fed Mopar]

No mods, none that I know of anyway. Supposedly it is a '68 383 HP engine. Not sure where the numbers to check that? Don't really know what the timing is at, I need to borrow my neighbor's light and check. I just kinda turned it up until it started and revved good.

 

[Cranky]

How much can you keep turning it before it starts to ping? Has it ever been rebuilt?

 

[696pack]

I have an NOS vacuum advance with the part number of 2875096 that shows as the correct one for a 1968 383-4 and the arm is marked as 10.5L

It is for sale if you need the correct one.

 

[Force Fed Mopar]

How much can you keep turning it before it starts to ping? Has it ever been rebuilt?

Haven't driven it yet, don't want to take off down the street w/ a loose can of gas in the trunk and questionable brakes I gotta get some more gas and a timing light and get it cranked up again and check where it likes the timing. Probably get that done this weekend. If I had to guess I have to set it up to about 15 degrees initial for it to act right. The advance springs are pretty stiff, there is no slack in either and I can turn the governor to about 3/4 of the travel available in the slots, so the secondary spring must be pretty heavy.

AFAIK the engine hasn't ever been rebuilt. The car hasn't seen the road in 15 years probably, and may have only seen track duty then (has traction bars in the back and adjustable shackles, front end was jacked way up when I got it).

 

[Force Fed Mopar]

So I set it to 5* initial, and it runs and revs decent. Watching the timing w/ a dial-in light, it seems to break up over 34*, but the revs are really high when it goes over, like 3500-4k probably (no tach yet), so not sure if it's fuel or timing causing it to break up. Might try it at 3* initial. Lol it's kinda weird, never had an engine that could run so little initial timing.

Still can't hook up the vacuum advance though, hooked it to ported vacuum and it stumbles hard and tries to die when revved. Can't be the right pod, I have a 9L pod on my 440 distributor I may try on it.

 

[lewtot184]

the '68 and laters had 15-17 degree plates; smog stuff.

 

[Force Fed Mopar]

So this might be a 68-71 distributor? It has a 15.5 plate. Engine is supposedly a '68 HP. Could be that this isn't a HP engine either, maybe just a regular 383 4bbl. The VIN on the car says it was originally a 318 car, so who knows lol.

 

[tpodwdog]

heres an idea...and just an idea. make sure the bushings in that dist. are ok. you may be breaking up because of the points . one degree in dwell changes one degree in timing...........that is of course you do have a points dist. i read the thread 6 times and it says nothing about point or electronic ignition.

 

[lewtot184]

So this might be a 68-71 distributor? It has a 15.5 plate. Engine is supposedly a '68 HP. Could be that this isn't a HP engine either, maybe just a regular 383 4bbl. The VIN on the car says it was originally a 318 car, so who knows lol.

if the distributor is all original its probably a '68 or '69 automatic transmission unit. i'm not sure i'd get too lost in whether its hp or not. its usable and the advance plates can be changed or modified.

 

[green1]

Ping it, back off 2; try hot start. if good, now raise initial to highest vac or rpm.. Calc yhe #'s, then re-curve. then work on carb.

 

[Force Fed Mopar]

heres an idea...and just an idea. make sure the bushings in that dist. are ok. you may be breaking up because of the points . one degree in dwell changes one degree in timing...........that is of course you do have a points dist. i read the thread 6 times and it says nothing about point or electronic ignition.

I took it apart and checked everything out, bushings seemed good, no wiggling at all in the shaft.

if the distributor is all original its probably a '68 or '69 automatic transmission unit. i'm not sure i'd get too lost in whether its hp or not. its usable and the advance plates can be changed or modified.

Yeah it'll get an electronic dizzy later on, just want to get it as good as possible with the points until then. Probably be on the points for another year or two.

 

[Force Fed Mopar]

Ping it, back off 2; try hot start. if good, now raise initial to highest vac or rpm.. Calc yhe #'s, then re-curve. then work on carb.

Ping at WOT right? Hope to have it drivable in another month or so, but you know how that goes :happy11:

 

[Cranky]

Need to put it under a load when tuning that way. Low speed high load condition it will ping if the timing is too far up. Lower compression engines with lousy quench have a tendency to ping before a higher (to a point) compression engine with better quench will. But with that said, lower compression engines tend to like more timing if you want them to run good. Key is how to do that without them pinging their guts out. One area to keep in mind is water temp. The hotter they run, the more they usually ping. Camshafts that create a lot of cylinder pressure will make just about any low compression/lousy quench engine ping AND detonate but there are some that work pretty good.

 

[bigmanjbmopar]

Thread high jack........Is there a kit to upgrade to electronic that goes in the stock dizzy? and can be used with the msd 6AL? Sorry for the high jack.....stock 383 dizzy thanks....

 

[bigmanjbmopar]

Directly from the factory service manual performance curving.

http://www.imperialclub.com/Repair/Lit/Master/265/Page04.htm

http://www.imperialclub.com/Repair/Lit/Master/265/Page05.htm

 

[Force Fed Mopar]

Interesting, I'm under the impression that a rich mixture needs less timing?

 

[Meep-Meep]

Thread high jack........Is there a kit to upgrade to electronic that goes in the stock dizzy? and can be used with the msd 6AL? Sorry for the high jack.....stock 383 dizzy thanks....

For the MSD you can just use the points to trigger it and since they will only see low current they will last darn near forever in that situation. The other option is to use a Pertronix to trigger the MSD.

 

[Meep-Meep]

Interesting, I'm under the impression that a rich mixture needs less timing?

A rich mixture should burn faster and start to burn easier than a lean mixture so I believe you are correct. Also a rich mixture will have a higher EGT too.