High idle and early timing..

[mopar400]

Hi Guys
could someone please tell me, simple as possible, how to set my idle (curb) its a -75 thermoquad, I´ve bought the "1973 dodge chassis service manual" (the car is a 1973 charger, 400,AT) and it writes a novel about using exhaust gas analyzer and so forth...seems a bit overkill.  or..

My Idle is at 1100, should be 700rpm acc to emission label in car..
also I shecked the ignition timing (at Neutral, Distr vacum plugged) and found it VERY early (outside the scale so about 20 degrees...)
what would be the purpose of settin idle high and timing early?

//Linus

[greenpigs]

You sure that its on the number 1 wire?

[mopar400]

The one in the front, driver side, yapp!
checked it on different occations to..

[firefighter3931]

Every Big Block Mopar i've tuned has responded well to lots of spark lead at idle. It's mostly dependant on the engine combination (cam/compression etc...) but even on a stock engine i would set the base timing at 15* then check the total. After the timing is set simply adjust the idle speed screw down to achieve the desired idle speed.

As for the original question...increased timing will create more manifold vacuum and that will increase idle speed....all things being equal. Allways set the timing first then move onto the fuel curve. 



Ron

[mopar400]

thanks Ron!
Now to the next issue, I cant seem to turn the distibutor it is "stuck"!
Do you know a good way of breaking the seal, i suppose the o-ring has dried up making it hard to rotate...

/Linus

[b5blue]

Tap a flat screwdriver between the block and base after soaking it with PB Blaster, be careful it may have crusted up in there as the metals are dissimilar.

[firefighter3931]

Tap a flat screwdriver between the block and base after soaking it with PB Blaster, be careful it may have crusted up in there as the metals are dissimilar.

Good advice....i was going to suggest a good soaking with PB blaster but Neal beat me to it. 


Ron

[greenpigs]

So Ron is that 15 advanced or btdc? I have mine at 6 btdc. Hmm I guess things need tweaked.

[firefighter3931]

So Ron is that 15 advanced or btdc? I have mine at 6 btdc. Hmm I guess things need tweaked.

Advanced and BTDC is the same thing. ATDC would be retarded or "late" timing. 


Ron

[mopar400]

Every Big Block Mopar i've tuned has responded well to lots of spark lead at idle. It's mostly dependant on the engine combination (cam/compression etc...) but even on a stock engine i would set the base timing at 15* then check the total. After the timing is set simply adjust the idle speed screw down to achieve the desired idle speed.

As for the original question...increased timing will create more manifold vacuum and that will increase idle speed....all things being equal. Allways set the timing first then move onto the fuel curve. 



Ron

Ok Ron after setting the timing and adjusting the Idle screw,  do I need to adjust the mixture screws? How?
//Linus

[firefighter3931]

Every Big Block Mopar i've tuned has responded well to lots of spark lead at idle. It's mostly dependant on the engine combination (cam/compression etc...) but even on a stock engine i would set the base timing at 15* then check the total. After the timing is set simply adjust the idle speed screw down to achieve the desired idle speed.

As for the original question...increased timing will create more manifold vacuum and that will increase idle speed....all things being equal. Allways set the timing first then move onto the fuel curve. 



Ron

Ok Ron after setting the timing and adjusting the Idle screw,  do I need to adjust the mixture screws? How?
//Linus

Linus, you might have to adjust the idle mixture screws....depends on how well the engine is idleing. The mixture screws on a thermoquad are on the front side of the baseplate. Turning the screws in leans out the mixture....backing them out richens the idle mix. 

If the exhaust smells rich then lean out the mixture. Pull a sparkplug and look at the color....it should be a nice tan to light brown. A good starting point is 1 1/4 turns out for the idle mixture. Just turn the screw all the way in and back off 1 1/4 turns and adjust from there.


Ron

[FLG]

Theres a few guides to adjusting thermoquads. I have one myself on 73. Same as yours, 400/AT.

I found that she responds best with base timing at about 13 or so and the vac advance hooked up to full manifold vacuum.

[b5blue]

2 things....1.Manifold vacuum drops like a rock when you punch it....there should be a carb port for that, 2. Set at 6* your idle will probably raise a good bit when you get to 14* so you may need to reset curb idle also to get RPM to settle down so you can adjust air/fuel. It's a good idea to go back and forth a few times checking. Rev the engine up enough to see how much advance your getting from centrifugal advance a few times while your there with the timing light (over 3K) to check function.(I had a new rebuild that only moved 6* instead of 15-20) Get this right and this engine should "wake up" quite a bit. These numbers are not absolute, the engine will tell you what it wants, set it, drive it, set it again and so on. Make certain your plug wires are 100% good, if not PM Ron.       

[mopar400]

thanks Ron!
Now to the next issue, I cant seem to turn the distibutor it is "stuck"!
Do you know a good way of breaking the seal, i suppose the o-ring has dried up making it hard to rotate...

/Linus

I came up with a solution the other day, I tried to turn the distributor when the engine was cold and it worked!
When its hot its impossible to move it, ever heard that before! AND
I played around with the vacuum advance to, It seems the engine runs better without the vacuum pluged in!
Anyone had experience that before? Isnt the vacuum advance supposed to "help" the engine?
advancing the timing while idling and under heavy load etc..

[greenpigs]

Thats why it needs to be hooked up to a ported vacum source.

[mopar400]

Worked on the car this weekend
Seems like the vacuum advance was the problem.
I took it of and tried to move the shaft, it was very hard so I adjusted the spring with an allan wrench
to make it move more easy..
put it back on, turned the distributor a bit (so I wouldent have to much advance)
fired it up and it worked!
then I adjusted the idle down a bit and set the air/fuel mixture screws to best manifold vacuum!
after that it was a joy to drive!

/Linus

[b5blue]

 

[Hemidog]

what is your timing now?

I'm having some issues with my 400..

http://www.dodgecharger.com/forum/index.php/topic,61723.0.html

[mopar400]

what is your timing now?

I'm having some issues with my 400..

http://www.dodgecharger.com/forum/index.php/topic,61723.0.html

Initial is set to about 10 degrees,havent messured the total advance yet.