'69 383 Setup Headache

[Addabob]

Hey All! New to group, but have been reading it for quite some time. I have a question around timing setup, as I am getting my rump whooped... I am not a motor genius, so no audible laughing allowed if/when I ask something stupid.

i started with a bone stock '69 383 2bbl motor and 727 transmission. It ran Ok but was totally gutless. Distributor Vac Adv was not connected to the Carter carb, so tried it but it was shot. Again, ran reasonably smooth. It has 104k miles on it.

i have now replaced the intake manifold and the carb to Edelbrock (2183 intake and 1806 4 bbl carb). Also replaced the distributor wth a Pertronix Flamethrower 3 with vac advance. Nothing else has been changed. Manifold vacuum is running in the 18-19" range, strong and steady.

So, I initially setup base timing to 12* and used the default Pertronix mech advance of 24*, verified total advance of 35-36*. Setup carb with vac gauge to best lean mixture. Hooked up vac advance to full manifold and am getting 15-16*. Idle set at about 900-1000rpm, and is smooth. Took it out for a drive, and it really bogs down and chugs with any amount of more aggressive acceleration from a stop.

I have tried setting up the timing in about every permutation I can with the Pertronix limiters. Read the Diamondback Engnes tech paper that said with a 241-260 cam duration (stock cam is 256-260 according to the Plymouth Service Manual) to set initial to 20*, which I tried along with the 16* mech advance limiter to maintain the total timing of 36*, but It still exhibited the same behavior...

I am just not sure where to go from here... Any suggestions would be welcome and appreciated. Again, I am new to engine work, so will do my best to answer any questions you may have.

thanks all! Have a great weekend, and a Merry Christmas!!

 

[mopar 3 B]

Hook the vacuum advance to ported vacuum or disconnect it completely and made sure the carb is set up correctly.

 

[Addabob]

I did all of the base timing and carb setup with the vac advance disconnected and the manifold vac port plugged on the carb.

Also, how quickly should the centrifugal advance come all in? Right now, the spring is setup to start centrifugal advance at 1500 and all in by 3500. Should I lighten the spring to start at 1k and all in by 2k...?

thanks all

 

[mopar 3 B]

I can not find information on your intake and carb setup. Single plane or duel plain and carb specifications would be of great help here!

 

[Addabob]

Sorry, intake is Edelbrock 2186 Performer 383 and is dual plane. 1806 is 4bbl 650cfm with electric choke.

 

[miller]

Idle at 900-1000 rpm? That puts the carb already out of it's idle circuit. Impossible to set carb mixture out of idle.
That thing should idle 650-700 rpm, if not lower.

 

[dryheat]

Silly question from a fellow non-motor genius. Did you plug or block off the EGR ports on the manifold?

Also some of those Performer manifolds require an adapter for the Thunder series carbs ... you may want to verify.

Welcome aboard also!!!!

 

[Addabob]

Idle at 900-1000 rpm? That puts the carb already out of it's idle circuit. Impossible to set carb mixture out of idle.
That thing should idle 650-700 rpm, if not lower.

Well, idle was set lower during the carb adjustment, but engine kept stalling when the tranny was put into gear. Used the idle screw to increase to about 900 as I thought I read another post recommending to do that. Maybe I messed that up...?

 

[dieseldazzle]

what happens when you add more timing? Does it ping?

- - - Updated - - -

what happens when you add more timing? Does it ping?

i feel you can get away with more initial timing, vac off of course. Then up to 38 degrees total out of that motor

- - - Updated - - -

Also did you put a light on it and verify total timing and if so what rpm is it all in by?

 

[Addabob]

Silly question from a fellow non-motor genius. Did you plug or block off the EGR ports on the manifold?

Also some of those Performer manifolds require an adapter for the Thunder series carbs ... you may want to verify.

Welcome aboard also!!!!

Well, I didn't see any requirements for any adapters for this manifold/carb. What would it need to adapt for...?

As for EGR ports, there are 2 and I plugged them at install. Manifold vac signal is strong at about 19", which I think is pretty decent for having 104K miles and no rebuild.

 

[miller]

I did all of the base timing and carb setup with the vac advance disconnected and the manifold vac port plugged on the carb.

Also, how quickly should the centrifugal advance come all in? Right now, the spring is setup to start centrifugal advance at 1500 and all in by 3500. Should I lighten the spring to start at 1k and all in by 2k...?

thanks all

Only distributors I've ever used are dual point, Mallory or Prestolite...
But, that being said, it's all basic stuff. Total advance normally comes in around 2 grand. Think of things another way...with advance full in at 2000 rpm, sets it around 35, or so, what the motor likes for running. The advance is coming off a 'retarded' timing set, that simply makes starting easier.
Unless there's something going on with your ignition, it's all way too high set. Initial 10-15, total 35-38...just tossing numbers out, so you can see the range. Point is, initial timing should be at idle speed. Timing works together with carb mixture setting, to get the thing to run all through it's range, idle to highway speeds.

Carbs, all I've used were four holers, and never adjusted mixture off idle. You usually set one, to get the other set, if that makes any sense. Sounds like advance springs need to be lightened, so once off idle, advance starts. Other spring deal is the 'rate' of advance, that controls how fast it comes in.

 

[Addabob]

Only distributors I've ever used are dual point, Mallory or Prestolite...
But, that being said, it's all basic stuff. Total advance normally comes in around 2 grand. Think of things another way...with advance full in at 2000 rpm, sets it around 35, or so, what the motor likes for running. The advance is coming off a 'retarded' timing set, that simply makes starting easier.
Unless there's something going on with your ignition, it's all way too high set. Initial 10-15, total 35-38...just tossing numbers out, so you can see the range. Point is, initial timing should be at idle speed. Timing works together with carb mixture setting, to get the thing to run all through it's range, idle to highway speeds.

Carbs, all I've used were four holers, and never adjusted mixture off idle. You usually set one, to get the other set, if that makes any sense. Sounds like advance springs need to be lightened, so once off idle, advance starts. Other spring deal is the 'rate' of advance, that controls how fast it comes in.

Thanks Miller for the lesson. Makes perfect sense. I will move to the lighter Pertronix springs to let the mech advance come in earlier and see how that works. As for the sluggishness, I think that I must not be setting the carb correctly and will focus more effort there. I will eventually get this all figured out.

Thanks again!!!

 

[lewtot184]

the diamond back cam timing is referring to 241-260 at .050" lift not 256-260 seat timing, so don't use this method. the timed port on carter type carbs is very aggressive and goes into full manifold vacuum quickly. you may be too aggressive with the timing curve; especially with that much vacuum. also check the fuel pressure and make sure there are no filters or restrictions on the suction side of the pump.

 

[Addabob]

what happens when you add more timing? Does it ping?

- - - Updated - - -

what happens when you add more timing? Does it ping?

i feel you can get away with more initial timing, vac off of course. Then up to 38 degrees total out of that motor

- - - Updated - - -

Also did you put a light on it and verify total timing and if so what rpm is it all in by?

Sorry Diesel - I missed your reply.

It never pinged when I added more initial, but I will say that when I went to 20*, I put in the 16* mech advance limiter to keep total timing to below 38*. I was all in at 36-37* by 3200-3300rpm. Vac advance is 15* max when connected after setting initial.

thanks!

- - - Updated - - -

the diamond back cam timing is referring to 241-260 at .050" lift not 256-260 seat timing, so don't use this method. the timed port on carter type carbs is very aggressive and goes into full manifold vacuum quickly. you may be too aggressive with the timing curve; especially with that much vacuum. also check the fuel pressure and make sure there are no filters or restrictions on the suction side of the pump.

Thanks Lewtot for the clarification, and hopefully you have stopped rolling on the floor laughing by now. I said I was new to this... ;-) But I am trying to get educated.

i am going to go back to the traditional ranges, and shot for the 12-14* initial range, and use the 24* mech advance max default on the Pertronix. I may also try the lighter springs so that the mech advance comes in sooner if that would help overall performance. Not looking for a race car, but something with some guts when I want to step into it. 98% of the time it is cruising and going on beer store runs...

 

[lewtot184]

a typical non-smog era 2bbl big block would have had 10 degrees initial and around 24 degrees in the distributor; all in around 4000rpm. this can be played with (brought in sooner). the fly in the ointment is the vacuum advance. how many degrees are in it? at what vacuum is it fully in? and, is it adjustable? i do recommend running the vacuum advance, just figure out what it is.

 

[Addabob]

a typical non-smog era 2bbl big block would have had 10 degrees initial and around 24 degrees in the distributor; all in around 4000rpm. this can be played with (brought in sooner). the fly in the ointment is the vacuum advance. how many degrees are in it? at what vacuum is it fully in? and, is it adjustable? i do recommend running the vacuum advance, just figure out what it is.

According to Pertronix, the vac can starts at 7" and is all in by 14", providing a max of 15-16*. It is not adjustable, but there might be one available for upgrade. I am running on the full manifold vac port on the Edelbrock 1806 carb, and not the timed port. So at idle I should be at initial + 15*, so maybe 27-ish if I set initial to 12. Then on heavy acceleration, vac advance drops out, and replaced by mech advance coming in at 1k, with 24* all in by 2k with the lighter spring. The medium spring starts mech at 1500, all in by 3500 rpm... Was just gonna experiment with the springs, once I am sure I have the carb adjusted correctly.

silly question... I am converting from 2bbl to 4bbl. I have the stock service manual that has adjustment specs for both. Are all of those settings out the window now as suggested starting points? If not, do I now use the 2bbl or 4bbl settings? Cam and compression were different for 2bbl to 4bbl, and cam is still the 2bbl original...

My sincere thanks for the great guidance from everyone. I am educatable!!!!

 

[dryheat]

Well, I didn't see any requirements for any adapters for this manifold/carb. What would it need to adapt for...?

As for EGR ports, there are 2 and I plugged them at install. Manifold vac signal is strong at about 19", which I think is pretty decent for having 104K miles and no rebuild.

After some research the 2186 manifold is not listed as one of the manifolds that requires an adapter for a square bore carb.

 

[lewtot184]

According to Pertronix, the vac can starts at 7" and is all in by 14", providing a max of 15-16*. It is not adjustable, but there might be one available for upgrade. I am running on the full manifold vac port on the Edelbrock 1806 carb, and not the timed port. So at idle I should be at initial + 15*, so maybe 27-ish if I set initial to 12. Then on heavy acceleration, vac advance drops out, and replaced by mech advance coming in at 1k, with 24* all in by 2k with the lighter spring. The medium spring starts mech at 1500, all in by 3500 rpm... Was just gonna experiment with the springs, once I am sure I have the carb adjusted correctly.

silly question... I am converting from 2bbl to 4bbl. I have the stock service manual that has adjustment specs for both. Are all of those settings out the window now as suggested starting points? If not, do I now use the 2bbl or 4bbl settings? Cam and compression were different for 2bbl to 4bbl, and cam is still the 2bbl original...

My sincere thanks for the great guidance from everyone. I am educatable!!!!

first, use the timed port. unless the heavy spring is elongated like a stock distributor heavy spring both springs work in conjunction with each other. if it were me i'd baseline the ignition curve like a stock non-smog 4bbl. using 24 degrees in the distributor and 10-12 initial. bringing the curve all in by 2500rpm should be sufficient with that small cam. don't expect big torque from those low compression 383's. the 10:1 383's never made enough torque to begin with and the 8:1 engines are dismal.

 

[dieseldazzle]

The vacuum advance should only have any effect on timing at idle and part throttle

 

[Addabob]

first, use the timed port. unless the heavy spring is elongated like a stock distributor heavy spring both springs work in conjunction with each other. if it were me i'd baseline the ignition curve like a stock non-smog 4bbl. using 24 degrees in the distributor and 10-12 initial. bringing the curve all in by 2500rpm should be sufficient with that small cam. don't expect big torque from those low compression 383's. the 10:1 383's never made enough torque to begin with and the 8:1 engines are dismal.

Lewtot - What is the reason for using the timed port as opposed to full manifold for vac advance? I have read a bunch on that topic, and most articles seem to say that timed ports were the precursor to smog controls and trying to reduce NO emissions by retarding ignition and not getting a complete burn at idle. Full manifold vac to distributor kept the timing advanced since the AF mixture was lean and needs the advance for best efficiency and longer burn time. NOTE - this is all just reading the various papers and forums on this topic, and it is very confusing when there is not a clear consensus... Not really black and white...

And as for the compression, the service manual says that the 2bbl was 9.2:1 and 4bbl is 10:1, so in line with what you said. I know it will never be a "street sweeper" in terms of awesome power, but still enough to blow some tire smoke every so often, I hope... ;-)

- - - Updated - - -

After some research the 2186 manifold is not listed as one of the manifolds that requires an adapter for a square bore carb.

Jim -

Thanks for the confirmation. I appreciate the double check on that, as I could have been chasing my tail had it needed one.