67 Plymouth 383 timing specs

[mfj]

Good day,

I have owned my bellvie for 11 years and I feel kind of ashamed to be asking something I should know. I recently swapped out the original 2bbl carter and manifold for a 71' 383 4bbl manifold with a Holley 4160. while tuning the new carb I noticed my vacuum advance was shot (I could use it as a straw). I replaced the old dist, and proceeded to check my timing. It was set at 5 atdc, been like this for as long as I have owned it. Now the problem is that I have found conflicting reports of what my timing should be. I have found 12.5 btdc, 5 btdc, 5 atdc... and so on. The manual I have only gives specs up to 1966, and I don't want to guess. If anybody can shed some light on where my timing should be it would be greatly appreciate.

My car specs:
1967 383 bone stock internals, no rebuild
1971 383 4bbl dual plane manifold
holley 4160 660cfm
stock 727
no ac
points style ignition
8 3/4 rear end stock
high level of badassness

This picture was taken just before I moved her down to the new house. She runs but was not registered at this point and wasn't taking any chances.

 

[69 Runner]

Bottom line is you set the timing where it runs best. Just use the book settings as a starting point.

 

[mfj]

Which book settings should I use? The book says for 270hp/383 2bbl 5deg btdc, for the 280hp/383 4bbl 5deg atdc. I tried the 5deg atdc first because that is where it was always at and upon goosing the throttle the third time it back fired through the primary side of my carb. so I figured "well that ain't right" it was at that point I went to 5deg btdc. Took the car out for a ride and it stumbles through- out the rpm range, darn near un-drivable. Now I didn't drive the car at 5deg atdc, due to the backfire but earlier in the day she ran like a dream at that setting without vacuum advance and the old dist(aside from a slight stumble upon initial acceleration) So, with that said, I am not quite sure where to go from here... 12.5btdc baddest stumble, 5btdc bad stumble and hesitation, 5atdc backfire out carb but smooth running??? Maybe 12.5 atdc it's the only one I haven't tried.

 

[mfj]

So I set the timing last night by ear/feel, took me about 7 adjustments but got it to where it runs best, however there is still a stumble when going up hill or at half throttle. So what does this mean? Oh and my dwell is set at 25% but the gap is .010! started at.019 and got 2%. think about it and let me know what you think.

 

[69 Runner]

These new points? If so, then my guess would be the cam on the distributor shaft is worn and the lobes aren't edged any more. If they're old points, then the lil hootis that rides on the distributor cam is worn down

 

[mfj]

Brand spanking new distributor. came with new points and condenser. I did not replace the cap and rotor or the coil. cap and rotor seem to be in tip top shape. Kinda mystified right now...

 

[mfj]

Mystification...gone. I am done beating around the bush. Full electronic ignition on the way. Pertronics ignitor 2, 40,000 v coil, plugs, wires, cap. Hope this helps with the timing/dwell issue.

 

[mfj]

SOLVED: it was the jets in the carb!!!! oh I rue the day I didn't change them, I thought they were small but had no idea how big they needed to be.