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Distributor spring recommendations
https://slantsix.org/forum/viewtopic.php?t=30579		 Page 2 of 3
Author:  Eric W [ Sun Aug 17, 2008 10:29 pm ]
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Guess I should have mentioned I have a 15R governer...... :oops:
Author:  Reed [ Fri Aug 22, 2008 11:52 pm ]
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OK, I'm back and ready to start sussing this out.

So, I need to step up to a "heavier" "light" spring?

DI- I honestly no longer know what were the "stock" springs in this distributor. Could you recommend which ones in that picture I posted would be "godd" springs to use?

The VC-208 can STILL hasn't shown up yet (last time I order from Napaonline...) so I am just going to stick with the advance can that is on the van.

Now I need to get the dial bakc timing light working to get some idea of what the mechanical advance curve looks like.
Author:  Reed [ Sat Aug 23, 2008 4:39 pm ]
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:D :D :D BIG thanks to emsvitil for the power valve adjustment instructions! Turns out the mechanical power valve on this Holley 2280 was way out of adjustment. I adjusted it this morning and took the van for a test drive. MUCH better! Way more power, especially above 2500 RPM/55 MPH.

Now I am going to go back and fine tune the distributor curve. It still needs some work in the off-idle and mid-range. I am going to try a heavier short spring and see if that helps.

I think it is getting pretty close though. THe van now gets up to 65+ with lots of pedal travel left and I can actually pass people on the freeway! :twisted:
Author:  Reed [ Sat Aug 23, 2008 5:11 pm ]
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Houston, we have a problem.

I got my dial-back timing light working (turns out all the cable attach to the gun via a PLUG in the handle, the plug had come loose). I went out and attempted to map out the mechanical advcance curve and here is what I got:

(vacuum advance disconnected)

From idle (750 RPM) through 1200 RPM the timing stayed steady at the initial base setting of 10 BTDC.

At 1300 RPM the timing was 11 BTDC.

Between 1400-1600 timing bounced between 10 and 12 degrees BTDC.

From 1700 ROM through 2200 RPM timing bounced between 8 and 12 degrees BTDC. I didn't bother going any higher since something is definitely wrong with this picture.

Are my springs too heavy? Why does the timing mark bouce?

As soon as the motor cools off I am going to pull the distributor and dissect it again. :?
Author:  Reed [ Sat Aug 23, 2008 6:46 pm ]
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Now I'm getting somewhere!

The loop on the previous heavy spring was so long and the lght spring was so light that the distributor basically went to full mechanical advance as soon as the motor was started. Not good. I swapped out the heavy spring with the long loop for the shortest heavy spring, and I switched the light spring for the "heavy" light spring.

NEW results, mechanical only advance, base timing is 10 BTDC:

650 RPM = 10 BTDC
800 RPM = 12 BTDC
1000 RPM = 12 BTDC
1200 RPM = 14 BTDC
1300 RPM = 16 BTDC
1600 RPM = 16 BTDC
1900 RPM = 18 BTDC starting to get twitchy
2200 RPM = 18 BTDC twitchy

Now, since I have a R9 governor, I only should get 18 degree mechanical advance total, right? So I am only getting 8 degrees advance, less than half what I should be getting. Time to swap to a lighter "light" spring, yes?

:)
Author:  65Dodge100 [ Sat Aug 23, 2008 7:17 pm ]
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Author:  Reed [ Sat Aug 23, 2008 8:28 pm ]
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Thanks Danny!

I went back and I switched the short-heavy spring for a lighter heavy spring with a longer loop. I left the heavy-short spring in there for now and did another test:

650 RPM = 10BTDC (base timing setting)
800 RPM = 12BTDC
1000 RPM = 12BTDC
1150 RPM = 15BTDC
1300 RPM = 15BTDC
1700 RPM = 21BTDC (twitching begins)
1900 RPM = 22BTDC still twitchy
2100 RPM = 29BTDC, but timing mark bounces between 29 and 21 BTDC.

Since I have a R9 governor, I will only get 18 degree advance yes? So that would mean that my advance is "all in" by 2100 RPM, right? I concurr that the bouncing is the weight bouncing off either the end of the loop or the end of the slot in the governor. Any other ways to control this aside from a different spring?

I can't wait to take this thing for a test run tomorrow....

Thanks! 8)
Author:  Reed [ Sun Aug 24, 2008 9:58 am ]
Post subject: 
:twisted: :twisted: YEAHHHH!!!! This morning I swapped out the light spring for the heaviest light spring I had and then took it for a test drive. WOO-HOOO! I think I got it dialed in just about right. Good acceleration, plenty of power. I set my vacuum can so that it begins at about 14 inches and is all in by about 17.5 inches. That's the best I can do with the can I have.

Thanks for the help and suggestions guys! I think I got this thing curved. 8)
Author:  DusterIdiot [ Sun Aug 24, 2008 4:32 pm ]
Post subject:  Dial the cam in...
Reed,

You'll need to take the dizzy apart and dial the heavy spring cam in so it doesn't max... that 'scatter'/bounce will cause some grief while driving at high rpm (read: misfires and no so good mileage).
You'll have to pull the shaft out and dial the heavy spring 'cam' (post that you attached the loop to) and have the spring come short of the governor a bit so the spring acts as a shock absorber... you'll need an 11/32" wrench to roll that around...

The power is good, but watch your mileage and check plugs at various ranges... just because it feels good... doesn't mean it'll get better mileage,
or be nice to the engine....


-D.Idiot
Author:  Reed [ Sun Aug 24, 2008 5:09 pm ]
Post subject: 
Thanks DI! I will do another session of mapping the advance and see if the scatter didn't go away with the spring change. After the last mapping session I switched to a heavier light spring and double checked that the heavy spring stopped the advance before the weight hit the edge of the governor slot. I am hoping that the switch to the heaviest light spring did the trick, but I need to double check.

Otherwise, it runs great! It actually accelerates if I press on the throttle going uphill now! :wink:
Author:  Reed [ Sun Aug 24, 2008 6:52 pm ]
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:oops: Argh. Back to the drawing board.

I did a mapping session with what I thought was a good set of springs and here is the result:

600 RPM = 10 BTDC
750 RPM = 11 BTDC
950 RPM = 17 BTDC
1150 RPM = 22 BTDC
1300 RPM = 24 BTDC

I stopped at that point because the advance was coming in way too early.

I pulled the distributor and swapped in the heaviest and shortest springs that I had. Then i went back and did another mapping session. Here are the results:

700 RPM = 10 BTDC
800 RPM = 16 BTDC
1000 RPM= 18 BTDC
1300 RPM = 20 BTDC
1500 RPM = 20 BTDC
1850 RPM = 14 BTDC (I double checked)
2250 RPM = 18 BTDC

:shock: WTF? How does more RPM = LESS mechanical advance? It was looking better until I hit 1300 RPM. Plus, again, the timing mark was jumping quite a bit. I am beginning to suspect that the distributor is worn internally leading to a loss of accuracy at higher RPMs. It does have significant up and down play on the distributor shaft.

I guess I am off to the boneyard to find another distributor tomorrow. :x I saw a 76 Aspen wagon in the junkyard last time I was there, hopefully it is still there and still has its distributor...
Author:  65Dodge100 [ Sun Aug 24, 2008 8:40 pm ]
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Author:  Reed [ Sun Aug 24, 2008 9:04 pm ]
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Timing chain was replaced less than 10k ago with a NOS mopar Performance double roller unit. :x
Author:  emsvitil [ Sun Aug 24, 2008 9:10 pm ]
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How close is the pickup to another sparkplug wire?
You might be getting some interference.

Also, if you have an MSD ignition, the multiple sparks might confuse the timing light.
Author:  Reed [ Sun Aug 24, 2008 9:52 pm ]
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Stock Mopar electronic ignition. I will double check that the pickup is reading #1 only.
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