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Timing Spec's

Mopar Muscle
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Timing Spec's

firenicez firenicez
New User | Posts: 1 | Joined: 07/10
Posted: 07/17/10
04:46 PM

I have a 72 Duster and some1 previously pulled the 340 and put in a 383. The manual says to refer to label in engine compartment,but obviously its not the orig. engine. Why they just couldn't give the spec...I guess that would be too easy.
So if anyone knows the timing spec for a 383 I would appreciate the info.
It was sold to me as a "440" but I've check block numbers and to the best of my knowledge I believe its a 383. ID number is behing the alternator like a 383/400 and says 0383 ... unlike a 440 has the pad at the front of the intake. The molded number I believe is the date is on the drivers side and is 11 70..which makes me think it was built nov. 1970...but still don't know what it came out of...haha.
If we have alot of Mopar guys out here I would love any help in figuring out this car.
Thanks  Eric  

IQ52 IQ52
Guru | Posts: 860 | Joined: 06/10
Posted: 07/17/10
06:04 PM

IF the engine is still stock. IF the engine is a 383. IF the block was cast 11 70 that would make it a '71 model year. All these "IFS" being true, the '71 service manual says the basic timing is:

Manual transmission   TDC, +or- 2-1/2 degrees
Automic transmission  2.5 degrees BTC, +or- 2-1/2 degrees  

drmopar drmopar
Guru | Posts: 1445 | Joined: 02/08
Posted: 07/17/10
08:13 PM

Those specs are a lot of ifs, first they are for the 2 barrel 383. If it is a 4 barrel 330 hp 383 the specs are more like 10 degrees initial since it would have the performance cam in it.
So the real question is do you have the two barrel motor with the stock cam or is it a performance motor?
Once you find out you will be able to make the right adjustment.
If all else fails, set the total timing at 34 degrees at 3000 rpm with the vac. advance disconnected. Be sure to hook up the vac. line when your done.
Good Luck

IQ52 IQ52
Guru | Posts: 860 | Joined: 06/10
Posted: 07/17/10
09:14 PM

If I keep it simple, Im told to elaborate.

If I elaborate, I'm told to K.I.S.S.

"Doc" is correct, 34 degrees total is a good safe setting.

In the '1971 book', the specs for the high performance 4bbl are exactly the same as the 2bbl. That is why I did not break them down further.

They change a little from year to year.

In 1969 the booooook says for the 383 (I'm typing this very carefully Doc so as not to make any mistakes):

Manual          TDC
Automatic     7-1/2 BTC
Power Pack      TDC**          ** = 4 BBL Carb.

And these are general guidelines that I use:

<208 degrees @ .050" lift..............0-10 degrees initial
<220 degrees @ .050" lift.............10-12    "       "
up to 245 degrees @ .050".............12-20    "       "
245 to 265 degress @ .050".........18 to 22+   "       "
>265 degrees @ .050 lift.................22+   "       "

These guidelines float around a smidgen (depending upon the mood I'm in and what I may have been sniffing, i.e. cleaning solvent, carburetor cleaner, ethanol, 112 or tire smoke) and are "ballpark" figures just ment to get you close to your initial timing if you are using the proper fuel for your compression ratio.


drmopar drmopar
Guru | Posts: 1445 | Joined: 02/08
Posted: 07/18/10
02:55 AM

Good info, I like the chart as the cam duration increases showing the timing increase. This is the point I was trying to make regarding the 2 barrel vs. 4 barrel motor, the factory definitley used a stronger cam in the 4 barrel motor.
My 70 383 4bl hp road runner had a factory tag under the hood indicating initial timing @ 10 degrees.
However this was a Canadian Car and quit possibly had different specs than say a California bound car.

lucky1951 lucky1951
New User | Posts: 2 | Joined: 04/12
Posted: 04/20/12
02:25 AM

lucky1951 new here.  I have a 1970 340Duster and I can not find tune up specs anywhere.  also can any one recommend headers that won't hit the steering column?  

marcohotrod340 marcohotrod340
Enthusiast | Posts: 470 | Joined: 09/08
Posted: 04/20/12
03:32 PM

1970 340 n9yc plugs gapped at .035"  timing withvac. advance plugged is 10 degrees advanced at around 800 rpm to 12 degrees advanced or so if it has no pinging. hooker, hedman and tti headers fit  

lucky1951 lucky1951
New User | Posts: 2 | Joined: 04/12
Posted: 02/14/13
05:36 PM

Icon Quotemarcohotrod340:
1970 340 n9yc plugs gapped at .035"  timing withvac. advance plugged is 10 degrees advanced at around 800 rpm to 12 degrees advanced or so if it has no pinging. hooker, hedman and tti headers fit

Thank you for the help.  I just got it cranked up for the first time in around 20 years.  It is amazingly responsive.  Do you have any tips or tricks I need to know about in order to get all it can give?

Thanks,  Dan  

440roadrunner 440roadrunner
New User | Posts: 3 | Joined: 11/10
Posted: 03/08/13
10:55 PM

Forget  factory  timing listings.   From  68  (66 in CA)  those are all smog engines, and the distributors  are  curved  for  "smog"  settings.   So we have several  problems

1--Who  knows what cam is in the engine?

2--Who  knows what the distributor is out of and  what the curve is?

Start  by  checking  the timing marks  FOR ACCURACY  with a positive stop.  This is very easy to do.

Next,  do one of several things:   Either  measure up your damper and mark it in degrees,  get  timing tape,  or buy a degreed  damper.  Either that or buy a GOOD  "dial up"  timing light

Next,  "play"  with the timing  as suggested above,  to figure what the engine "likes"  for total  timing.  About  35 in this day and age  is  in the ballpark  for  full throttle,  /  no vacuum advance  (Vacuum advance  "goes away"  at  full throttle.)

Next  figure out what the engine  "likes"  at  idle/  low speed.   With  8-9:1 compression and  a mild cam,  15-17*  is not unheard of,  starts  well,  is responsive,  and gives you good low end.    "More cam"  can stand more,  20* or so.

Now  figure  "what is in?"  the distributor mechanical advance.  That is,  if you have a "smog"  distributor, it very likely has a very long and very slow advance curve which is going to do  one of two things:   Either over--advance on the top end if you have  a decent  idle  (initial)  setting,   or if you set it for  35  (or so)  full advance,  then the idle/ initial  timing  with  be very low,  "just like"  the smog  settings  called  for.

SO THEN  you need to consider either getting your distributor   "re--curved"  for a shorter,  quicker  mechanical advance,  or else  buy an aftermarket  distributor  WHICH HAS  an adjustable mechanical advance.

IT IS IMPORTANT  to understand  that  if you look in any spec/ shop manual,  normally distributor specs are listed in  DISTRIBUTOR  degrees  which is  HALF  of  "crank"  degrees.   Also,  many Mopar  weight mechanisms  are  stamped with  the advance figure.   So,  example,  if you se  "15"  on the advance mechanism,  this IS A  slow, "smog"  advance giving  you  THIRTY!!!  degrees at the crank!!!.  What this means,  then, is if you set the initial  to 10,  (not enough  in many cases!!)  the  total will be  35.   Vacuum is on top of  this,  but again,  "not effective"  at  WOT.

When you look  at  the 68---78  years  of  "smog"  junk,  you are likely to see anything  from  10*  (some 340/440s)  to  figures  ATDC,  IE  retarded  AFTER  TDC  and not before!!