Fighting with this 440 idle!

[AR67GTX]

I have no doubt the springs are correct. It's a fresh dist from Hallifaxhops all tested and curved.

If the one spring (call it the primary) is really a “light” one, it’s probably not original IMO. The use of that heavy spring (call it secondary) with the long eye requires more than a light spring to control advance as up to something like 4,000 rpm it’s the only spring controlling advance. Those heavy, long eye springs don’t start allowing the last of the centrifugal advance to start coming in until something like 4,000 rpm or even higher and probably won’t allow full advance until some ridiculous level like 4800-5000 rpm’s.

With a “light” primary spring the first half of your centrifugal advance swings in quickly at lower rpm’s and then it just stops when the weight pin takes up all the slack in the big secondary spring eye and the engine has to wind up to higher rpm until the secondary spring starts to stretch, allowing the rest of the advance to come in. So you have a 2 step advance curve with a plateau in the middle. It’s not a good set up. I believe Mopar used a medium weight primary advance spring to slow the initial curve down and shorten the plateau between initial centrifugal advance and later centrifugal advance. Either way that big heavy spring with the elongated eye is not a good performance set up.

As noted above, it would be a good idea to make sure the secondary blades are closing at idle when the engine is warm. I’ve found an AFB where the bent rod connecting primary and secondary blades on the right side was bent from age and use and would not open the secondary blades fully. I guess it’s possible that something could get out of wack and not let the primaries close at idle.

 

[Geoff 2]

I think it is unlikely that the throttles are binding, especially the secondaries. Lifting off the throttle from high rpm produces veeeeeery high vacuum under the blades. The throttle shaft is NOT in the centre of the blades, it is offset to facilitate closing of the blades. A safety feature. But make sure the linkage on the pri & sec shafts, pass side are correctly adjusted, not bent & hanging up.
Next time it does it, check the timing!!

 

[Macdon221]

So an update...

First I want to thank everyone for all of their help. I am a relatively young guy at this...mid 40's...but have always loved restoring old things back to original. Started with Gumball machines from the 30-50's, then vending machines, off to 1930's Johnson Outboards, late 70's Honda motorcycles, then my 68 Charger RT, now off to a 69 RT. Again...thanks for all your help.

Back to business...So no vacuum leaks to find anywhere...I did everything to try and highlight one. The primaries were closing right to the stop. Choke fully off. For the win...it was the Secondaries...man they were just hanging open just a hair. Touch the side of the carb and they would seat perfect. I adjusted the tabs on the passenger side and now all is good all all the time.

Looking for input on the timing of the newly rebuilt dist that I installed. It is the proper Chrysler numbered one for the car. Points. I do have a FBO plate in there. Set to the 18 slot. Given the CAM that i have in there as listed in my first entry... Here are the numbers....with a dial back light....vacuum advance plugged at carb port and at can....

15 degrees at idle....750rpm
21 degrees at 1000 rpm
29 degrees at 1200 rpm
32 degrees at 1500 rpm
34 degrees at 3000 rpm

no increase in timing when vacuum advance connected at idle.

at 2600 steady rpm with vacuum advance connected the timing is 54 degrees.


My thought is the timing is coming in too early? Thoughts? Again there is the heavy looped spring on one weight and a light one on the other weight.

It make tons of power...but still just a little stumble if I stab the pedal from stop. If I just hold the brake just slightly, and let off same time as add power it can be smoke city and then a chirp when it shifts into second! Any recommendations to help with that? I have selected sprigs that pop up upon throttle blip, stock tall 101 primaries, stock 95 secondaries and the very close to stock metering rod 16-575 (65x62x53). I have various rods and jets if need to change.



Thanks,


Macdon221

 

[Geoff 2]

No change in idle when vac adv connected to manifold vac?
Possible causes:
- faulty VA unit
- not connected to a man vac source
- with a 'cam', you have to use an adjustable VA unit, with the Allen Screw would fully CW [ softest spring setting ].


Your stumble is from insufficient timing at idle. With the correct idle timing [ 15* is waaaaay too low, needs 20-35* ], the engine makes more HP. With the extra HP, the engine can carry the load....& voila!....no stumble. Read below about ign timing, it is from the Edel manual...

 

[Geoff 2]

And what MVA does....

 

[turbine68rt]

4429's don't use manifold vacuum for the advance, only ported. Mine runs fine with timing at 18/18. I cured a slight off idle stumble with my AVS2 by swapping the stock Edelbrock discharge nozzles with a spare one from a parts 4429. The necked down tubes were too restrictive for the needed flow.

 

[Tony Tee]

You say the carb is rebuilt? We're the throttle shafts ok? Loose shafts can cause your problem.

 

[Orig69]

So an update...

First I want to thank everyone for all of their help. I am a relatively young guy at this...mid 40's...but have always loved restoring old things back to original. Started with Gumball machines from the 30-50's, then vending machines, off to 1930's Johnson Outboards, late 70's Honda motorcycles, then my 68 Charger RT, now off to a 69 RT. Again...thanks for all your help.

Back to business...So no vacuum leaks to find anywhere...I did everything to try and highlight one. The primaries were closing right to the stop. Choke fully off. For the win...it was the Secondaries...man they were just hanging open just a hair. Touch the side of the carb and they would seat perfect. I adjusted the tabs on the passenger side and now all is good all all the time.

Looking for input on the timing of the newly rebuilt dist that I installed. It is the proper Chrysler numbered one for the car. Points. I do have a FBO plate in there. Set to the 18 slot. Given the CAM that i have in there as listed in my first entry... Here are the numbers....with a dial back light....vacuum advance plugged at carb port and at can....

15 degrees at idle....750rpm
21 degrees at 1000 rpm
29 degrees at 1200 rpm
32 degrees at 1500 rpm
34 degrees at 3000 rpm

no increase in timing when vacuum advance connected at idle.

at 2600 steady rpm with vacuum advance connected the timing is 54 degrees.


My thought is the timing is coming in too early? Thoughts? Again there is the heavy looped spring on one weight and a light one on the other weight.

It make tons of power...but still just a little stumble if I stab the pedal from stop. If I just hold the brake just slightly, and let off same time as add power it can be smoke city and then a chirp when it shifts into second! Any recommendations to help with that? I have selected sprigs that pop up upon throttle blip, stock tall 101 primaries, stock 95 secondaries and the very close to stock metering rod 16-575 (65x62x53). I have various rods and jets if need to change.



Thanks,


Macdon221

To reduce the stumble increase the ignition timing to 17 degrees take notes on how it works and then try 19 degrees (with the vacuum advance hooked up and plugged)

Adjust the idle speed back to 750 rpm

 

[AR67GTX]

Well, it sounds good … but I would still be concerned about that heavy advance spring with the loop end. That thing doesn’t even start stretching until above 3000 is my guess, and can continue advancing all the way up to a much, much higher rpm.

Of course the FBO plate shortens the slot for the advance pins and it may be that the pin hits the end of the slot before the slack in the heavy springs even is taken up. But I think if a single light spring was all that was restraining the weights, all the advance would come in a lot earlier than 3,000. That’s why FBO recommends their springs for use with the plate. But the only real way to know exactly what the distributor is doing is to find someone with an old SUN distributor machine that can safely spin it all the way up to 5,000 rpm or so to make sure the max timing is what you think it is and that it’s stable.

 

[Macdon221]

Thanks for the relies!

Yes...VA connected to Ported as Turbine said.

Looks like that I can try to advance it a bit more at idle and see what happens with the stumble. The plate will still limit it at 34 degrees. On the dyno 34 is where it made the most power I think. I do know that dyno conditions are different.

Oh...here is a video of the actual engine getting dyno'ed. It's a good fun watch. Comment on anything you think needs commenting on.



And yes I know I have a 4429 on a 69 engine. Sending the proper 4618 to get done. 1 step at a time.

Does anyone think the timing is coming in too fast?

Are there different discharge nozzles to get for these AVS's? I know they have a number on them.

 

[WileE]

It seems like a linkage problem. When you said it started after a hard acceleration, perhaps you need a better return spring ( actually, you should have TWO ) to close the throttle completely.

 

[WileE]

Ooops, sorry, I jumped past the rest of the posts, I posted after I read the hard acceleration post. Anyway, a secondary return spring is good to have.

 

[jdsgtx]

Good Day All,

In need of some guidance.

As the title says....been fighting with a 440 to get it right. It's a newly built engine in the last year or so. A little bit of porting, comp cam #21-223-4. Nothing too crazy. Stock Heads.

The engine ran good, not perfect...a stumble off the line but that's about it. Idled ok after warm. Choke was not set up. It makes tons and tons of power. Stock intake. Stock original carter avs carb. Also had original dist with a pertronix pick up with the standard coil....extra wire ran to the ballast resistor. Started and idled ok.

I like things back to stock...just my thing....so I replaces the carb with a newly restored correct CARTER AVS carb. Same carb just restored. Same jetting. Stock 101 primaries and 95 secondary's. Spring set installed allows the to sink on idle and pop up when throttle is blipped.

I removed the correct original numbered dist that was installed, which is the original one to the car, and installed a correct numbered newly restored dist with points and condenser. No pertronix pick up.

Choke all working fine. Car will start, warm up no issue. Smooth idle. Idles done to about 650-750 in gear no issse. Can get lower if needed.

Dist has been set to about 15 initial. Have FBO limiter plate installed to ensure all in no more than 34. Reeving up and checking the timing confirms this. Dwell set to 30...checked with feeler gauges for the ballpark and with a dwell meter.

Removing the vacuum advance at idle makes no difference to the timing....so at idle the vacuum advance is not influencing the timing.

Now here is my nemesis....start, warm up, drive, all good. Tons of power through all ranges. Zero hesitation from off idle. Very responsive. Gear shift points are good. Start, stop, idles good. BUT.....after about 15-20 mins of driving and the car heats up....the idle rises to about 1500. If wont go back down. The throttle is closed and back on the stop screw...same as where we started at. It also wanders a from back to 1000 and then back to about 1500. I have repeated this cycle 3 times now...let it cool...next day...same thing. Great at the start...but after a good warm up the cars idle is again not correct.

So....I have changed the carb to another avs carb while car still warm...restart...same. Changed the carb base gasket multiple times, 4 hole, open ...same. I have switched the coil when warm to cool coil....same. I have capped all vacuum sources while warm....choke diaphragm, pvc port, vacuum advance port, brake booster port on engine, and vacuum headlight (69 charger) port....no change.

I have tried to find an carb or intake manifold leak with water, and propane....no luck.

Where from here?

1. Should I go back to the original dist with the pick up? Try a new condenser? New points?
2. Ballast resistor?
3. Continue to look for an intake leak and how?

I really appreciate all your guys/gals help. I love it when my car is working perfectly....and I need help for this one.


macdon221

I would start with the carburetor, checking the floats! Check fuel pressure! Recheck timing! Mopars are finicky and after making one adjustment you usually have to recheck everything! Had this same problem with my 68 GTX!

 

[turbine68rt]

I would start with the carburetor, checking the floats! Check fuel pressure! Recheck timing! Mopars are finicky and after making one adjustment you usually have to recheck everything! Had this same problem with my 68 GTX!

See post 23

 

[turbine68rt]

Of course the FBO plate shortens the slot for the advance pins and it may be that the pin hits the end of the slot before the slack in the heavy springs even is taken up

Exactly. If he's at 34° at 3k the mechanical advance is just about maxed out if he's using the 18° slots. Using that setting there will be little, if any, more advance between 3k and 5k based on his initial/mechanical setup.

 

[Moparfever65]

100% sounds like an air leak. Opens up when warm.

 

[Macdon221]

Are you suggesting I switch something up?

Assuming that when I bump up the initial timing to 18 degrees I should also change the FBO plate to the slot labeled16 degrees?

 

[forphorty]

Maybe it needs the Holley from the dyno test . LOL

 

[Macdon221]

Maybe it needs the Holley from the dyno test . LOL

I was wondering who was going to pick up on that. Well done! lol

The dyno was done with the stock AVS as well...Just not video'ed....I have the sheet...it was like 8 less HP.

 

[ckessel]

Sounds like the secondaries may not be fully closing. When it hangs up in high idle, manually verify that the secondaries are fully seated and see if it changes anything or stays the same.

The 3310-2, 780 com vac sec, that I picked up recently for the wagon had the secondaries partially open when the primaries were closed. I tweaked the link that goes between them some so that the secondaries stay closed at low rpm's.