distributor springs light enough ??

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stroker402

stroker402

1968 dart GTS convertible
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just finished curving my mopar dist.
installed a pertronix III unit and flamethrow coil.
changed out the slotted plate for a 8* .375 with a long looped stock spring and a medium spring.
when I'm setting up the total timing @ 34* and 20* intinal and total at 2500 rpm ,vac adv plugged ... the timing still wants to climb some more before it stops..appears to be another 4* or better.timing still wants to climb at 34* total and is not all in yet.....
is it because the stock tighter spring with the big loop is not stretched out to the max yet and probally needs a lighter spring in there to bring to a faster total at 34* ?
when tested right now.... it is has the stock big loop spring and a medium spring someone has replaced from the real light stock spring .
Thanks fabo's
 

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My first thought is get rid of the "big loop" spring. Stock curves were really long and sloooooowwwww. That really slow curve was the job of the "stock big loop" spring.
 
Thanks 67 dart273 ...
yeah that's what I thought ...... that larger hooped spring is taking way too long to stretch out . but why would it want to go past 34* total even if the slotted plate is at 8* ? shouldn't it max out at 34* total there and not climb anymore ?
isn't the slotted degree in that plate that limits total timing? or if that looped spring is not all the way stretched out yet at 2500rpms it will take more rpms to get it there? hence why it shows timing is still climbing at 2500rpm and up.
I have the timing set at 20 intial and 34 total .
 
Well IF the spring is actually holding it back (what I was thinking) then it will continue to advance.

First thing I'd do is put one or two light springs in and find out for certain what the advance actually IS in degrees.

THEN you can determine if the distributor drive mechanism is causing spark scatter or other problems, or maybe the bushings in the distributor ain't that great.

So confirm the AMOUNT of advance, they play with your springs.
 
I'd get rid of the big loop spring. Put a lighter spring on it.

Total is only done when it's actually all in, not some predetermined number like the mopar book likes to spout. If you are seeing timing still coming in above 2500, you need to keep going until it stops advancing. If that's 4K, so be it. Those big springs will hold off timing for a long time, they were there to reduce emissions.

20 + 16 is 36... not 34... :)
 
update !

Correction!

I went to check on my specs on that distributor I rebuilt and I have two medium tension springs in it .
I thought It had a tight looped spring in it but not so..
 
crackedback said:
I'd get rid of the big loop spring. Put a lighter spring on it.

Total is only done when it's actually all in, not some predetermined number like the mopar book likes to spout. If you are seeing timing still coming in above 2500, you need to keep going until it stops advancing. If that's 4K, so be it. Those big springs will hold off timing for a long time, they were there to reduce emissions.

20 + 16 is 36... not 34... :)
Click to expand...

Thanks crackedback ! Your right my mistake !
36* total .
 
still working on getting the correct springs for the weights on the dist.
I have several sb point and electronic distributors . parts donars

I'm looking at the springs inside and the lighter of the springs is usually about 10-13 coils . which would be the lighter spring on tension ? They look so similar . what is the "rule of thumb" on the spring tensions?.....is it more coils the less tension weaker the spring or less coils the more tension /stiffer ?..

I have another spring out of a BB mopar dist and it is shorter in length and less coils (7) appears to be a really weak spring. thinking about using that one. maybe it's an aftermarket spring kit .
someone mentioned a mr. gasket spring kit works Good.
Thanks guys !

john
 
Back in the 70's some of us with dual point dist's ran NO springs. The rubbing of the points would drag the advance back enough to start, and there you went. The point? Use whatever spring works. You don't really need two if one gives you the curve you want. Make sure there's a little lube on the advance so that it works freely
 
Light spring controls initial advance off of idle, in other words while idling light spring keeps mechanical advance from activating until rpm increases to set point where mechanical advance starts. Sometimes if one or two light springs are used to regulate mechanical advance through rpm range, this will allow governor weights to bounce off of the bottom of stop slots during rapid rpm increase. Bouncing creates several degrees of advance, and retarding in the 2600-2900 rpm range as these weights dance around for a bit until settled at higher rpm.

Using a heavy long loop spring will control this bounce, and progressively allow final three degrees of advance to occur smoothly by around 2800 rpm. The large long loop spring has no control over speed of initial mechanical advance impute, that function is solely controlled by the lighter spring.

I recurved my distributor so mechanical advance would not activate below 1500 rpm by light spring selection, and to be all in at 2800 rpm controlled by long loop spring. In park idle is 1100 rpm with this car several hundred rpm above stock mechanical advance set point. Previous owner drag raced this car, had removed the light spring, and idle timing was fluttering around up and down a few degrees in sync with cam induced lope. This made idle rpm more unsteady running up and down a hundred rpm or so, and the car a PIA to drive in traffic, or shift out of park into gear smoothly as the slightest throttle impute rapidly advanced timing which rapidly advanced several hundred rpm.

Distributor recurve spring selection available from this fellow on slantsix dot org: bigslant6fan
 
Update


worked on the dist curve today and installed one real light aftermarket spring for the weights and the other is a oem light spring . started it up and set it for 34 total and it does not advance anymore now .. Which is good! before it kept wanting to creap up past 34 total..

only thing I see now is that when it's idling , i see the timing mark jump way up for a second and back down to 18 initial. It must be right on the erge to start pulling that other spring open ??

It idles real slow and smooth ...like 700rpm

should that be of concern .. it idles great it is not missing a beat and the idle stays right there and does not change .
 
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