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 Post subject: Re: Ideal timing curve?
PostPosted: Thu Sep 06, 2018 4:17 pm 
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Joined: Fri Feb 29, 2008 10:49 pm
Posts: 1394
Location: Salem, Oregon
Car Model*: 58 Plymouth Plaza 2dr, 63 Valiant Signet 200 2dr
Josh,

Attached to this message is your timing curve mapped. It might provide some enlightening information for your questions.

~THOR~


Attachments:
File comment: Timing Curve mapped
Josh Mechanical Advance w-RPM.png
Josh Mechanical Advance w-RPM.png [ 10.14 KiB | Viewed 472 times ]

_________________
1958 Plymouth Plaza 2 door Club Sedan
1963 Plymouth Valiant Signet 2 door Hardtop

Find a better way to turn perfectly good fuel into noise; I dare ya.
VP - Cherry City Bombers Car Club
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 Post subject: Re: Ideal timing curve?
PostPosted: Thu Sep 06, 2018 6:06 pm 
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4 BBL ''Hyper-Pak''
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Joined: Mon Aug 27, 2018 7:49 pm
Posts: 27
Location: Southern Illinois
Car Model*: 1973 pymouth scamp 225
THOR-

Thanks for the Awesome graph!

The timing mark indeed has slipped. Before I started this venture I. Checked it and it was off by two degrees. I used as small long screwdriver as an indicator on where the top of the piston was on the compression stroke and worked the crankshaft in a clockwise and counterclockwise direction until I was sure I was at very TDC.

The governor that i have is a 15L. I believe l, and like you said the timing light doesn’t lie, that the number stamped on the governor is in distributor degrees. So to get crankshaft degrees i would double it, right?

Also I just got done welding the governor slot and putting the distributor on the motor when I saw your reply LOL its no big deal for me to file the weld down if need be. It actually needs more slight filing as im getting 11* total mechanical (24* with 15* initial) at about 2100rpm. What can I say?? I got excited with the spring kit from BigSlant6Fan :mrgreen:

The scamp is not a daily driver and at the moment the plates are expired so im not in a huge hurry to get it on the road. Im actually waiting for cooler weather to replace some rotting spots in the trunk and floor. Its to hot for me to do extensive welding.

This may be a dumb question THOR but, if the slots werent welded and I put lighter springs in it I would still see the full 30* advance plus my initial just sooner in the rpm range correct? According to wjajr 30-31* of inital+Mechanical advance is ideal. I know everyones motor likes something a little different but does that 30-31degrees hold true for most slant builds? Mine is mildy modified but pretty much stock.

Also im kind of starting to worry, I still havent heard any pinging throughout any of my testing/datalogging. In fact I dont think I’ve ever heard it before. I do have a fuel pump that knocks at random, and I made triple sure it is the pump with a redneck stephoscope.

Again thank you for plotting the graph for me.

-Josh


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 Post subject: Re: Ideal timing curve?
PostPosted: Fri Sep 07, 2018 12:18 pm 
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Joined: Fri Feb 29, 2008 10:49 pm
Posts: 1394
Location: Salem, Oregon
Car Model*: 58 Plymouth Plaza 2dr, 63 Valiant Signet 200 2dr
Glad I could help.

30-31 degrees "all-in" is perfect for a stockish slant. If you put lighter springs in it, you get more mechanical advance sooner. If you are "all-in" by about 2500, that's about right.

The cam turns half the speed of the crank, so it's a 2:1 ratio. 15 on the cam is 30 on the crank.

This isnt a dig, but frankly, unless you have a degree wheel and positive piston stop (which bolts to the block with the head off) I find it hard to believe you know exactly how many degrees the timing mark is off. I'm not saying you are incorrect, I'm just saying it's very difficult to nail down exactly how far off it is without a pretty specific process.

As far as pinging goes, the slant came with what I consider very low compression. You need to have a lot of advance, low octane fuel, or get it pretty hot before a stock slant will ping.

~THOR~

_________________
1958 Plymouth Plaza 2 door Club Sedan
1963 Plymouth Valiant Signet 2 door Hardtop

Find a better way to turn perfectly good fuel into noise; I dare ya.
VP - Cherry City Bombers Car Club
http://www.bomberscc.com


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 Post subject: Re: Ideal timing curve?
PostPosted: Fri Sep 07, 2018 10:30 pm 
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Joined: Wed Nov 06, 2002 1:57 pm
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Location: Everett, WA
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You also need a load on the engine. You won't get any pinging with the car sitting in the driveway.

The 15L governors where used during the '60s up to the mid '70s. You can tell because most of those cars call for the timing to be set at TDC. The late '70s on used the 9L governors, these cars called for timing to be set at12* BTDC. The change was done for emissions reasons.

The ideal curve is highly subjective to a specific car. My '65 Dart liked 15* BTDC with the black springs and a 9L governor. But it had a modified engine with a 4 speed and 3.5 gears. My old '73 Duster liked 10* BTDC with the green and blue springs and a 9L governor. That engine was basically stock with a auto and 2.73 gears.


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 Post subject: Re: Ideal timing curve?
PostPosted: Sat Sep 15, 2018 7:37 pm 
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4 BBL ''Hyper-Pak''
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Joined: Mon Aug 27, 2018 7:49 pm
Posts: 27
Location: Southern Illinois
Car Model*: 1973 pymouth scamp 225
Hey Thor,

No offense taken! I understand what you are saying. I “assume” that my timing was off by 2*. I dont have an accurate way to measure this but it was off and a new mark was made. I have been using the new mark for setting my timing and for all of my tests.

As if right now I am waiting for distributor parts. The original pickup seems to be on its way out the door. I get a steady reading of 326ohms on the 1000 scale regardless if the reluctor to pickup tooth location. The new pickup should be here soon and I am going to replace the reluctor and drive gear as well they are at least 8 years old and the car sat from 2015-2018 without running.

As soon as I get the dizzy rebuilt I will resume testing different springs.

Thank everyone for helping me understand recurving a distributor now when I go back and read other members topics about it I’m not so confused.

Thor and Kesteb- thank you for clearing up the questions concerning pinging.

-Josh


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 Post subject: Re: Ideal timing curve?
PostPosted: Mon Sep 17, 2018 1:03 pm 
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Joined: Fri Feb 29, 2008 10:49 pm
Posts: 1394
Location: Salem, Oregon
Car Model*: 58 Plymouth Plaza 2dr, 63 Valiant Signet 200 2dr
You betcha!

We're just trying to get another slant on the road! I'll keep an eye open for updates.

~THOR~

_________________
1958 Plymouth Plaza 2 door Club Sedan
1963 Plymouth Valiant Signet 2 door Hardtop

Find a better way to turn perfectly good fuel into noise; I dare ya.
VP - Cherry City Bombers Car Club
http://www.bomberscc.com


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 Post subject: Re: Ideal timing curve?
PostPosted: Wed Sep 19, 2018 12:02 pm 
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Joined: Fri Nov 01, 2002 11:04 am
Posts: 270
Location: New York
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I tune and am very familiar with many late model and custom tune high performance spark curves. With this in mind, this is what I did with my 1980 stock cam 1bbl slant with a lockup 904:

Modified the mechanical advance to give around 7 degrees total - 14 crank degrees. Set the base timing to around 16 degrees. Use springs to bring in total distributor advance at around 3500 rpm. Adjusted the vacuum advance for no preignition at part throttle.

There is no reason to run the base ignition timing at the factory 10 degrees (or less) other than emissions. My car ran cooler and was way more responsive with this tune. And I typically recorded around 24-25 mpg or better at 65 highway mph.

This was with a factory HEI distributor.

Mitch


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 Post subject: Re: Ideal timing curve?
PostPosted: Fri Sep 28, 2018 12:09 am 
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4 BBL ''Hyper-Pak''
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Joined: Mon Aug 27, 2018 7:49 pm
Posts: 27
Location: Southern Illinois
Car Model*: 1973 pymouth scamp 225
Ok its been a while,

Got the distributor rebuilt and I think I have the curve where I think it should be. Installed the blue and green spring and that brings my total timing all in slightly above 2400. Here is the curve as it is right now.

Initial set at 15* idles at 700
15 @ 800
15 @ 1000
15 @ 1200
17 @ 1400
21 @ 1600
23 @ 1800
26 @ 2000
28 @ 2200
30 @ 2400 (closer to 2450)

THOR- thanks for all the tips and advice I sure appreciate it! Cant wait to see how it acts on the road...

Mitch- thanks for your input. Question, why did you set you advance curve to be all in around 3500?

-Josh


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 Post subject: Re: Ideal timing curve?
PostPosted: Fri Sep 28, 2018 2:44 pm 
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Joined: Fri Feb 29, 2008 10:49 pm
Posts: 1394
Location: Salem, Oregon
Car Model*: 58 Plymouth Plaza 2dr, 63 Valiant Signet 200 2dr
Attached is what your timing curve looks like with your adjustments:



~THOR~


Attachments:
Josh Mechanical Advance w-RPM - New.png
Josh Mechanical Advance w-RPM - New.png [ 7.54 KiB | Viewed 223 times ]

_________________
1958 Plymouth Plaza 2 door Club Sedan
1963 Plymouth Valiant Signet 2 door Hardtop

Find a better way to turn perfectly good fuel into noise; I dare ya.
VP - Cherry City Bombers Car Club
http://www.bomberscc.com
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