Dizzy Erratic Timing

Engine, Transmission and related drivetrain.
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Beev
Posts: 10
Joined: 11 Apr 2018 13:49

Dizzy Erratic Timing

Post by Beev » 16 Jul 2018 19:10

Hello Again!

Car is running and passed inspection. I have been checking my timing and have a few questions/a problem. The engine is a L20b, or more specifically this:

http://www.the510realm.com/viewtopic.php?f=10&t=30763

1) My harmonic damper is the type with 4 notches. Can someone please confirm that it is -5, 0, 10, 15. As I was reading on:
http://www.davidcmurphy.com/olddat/620tech2.htm#TS

2) I noticed hesitation and missing during WOT and higher RPM leading me to check the timing. I had the following results (assuming I have the notches correct):
10 degrees advance @ 950 RPM
14 degrees advance @ 1850 RPM
16 degrees advance @ 2000 RPM
24 degrees advance @ 3100 RPM but the timing is unstable often jumping 5+ degrees advanced.
24 degrees advance @ 4000 RPM same issue

From what I have been reading these numbers are not nearly advanced enough (~12 @ 750 and 36 @ 3500) but with the erratic timing at high RPM I don't want to mess with it until that problem is fixed. I have been trying to search the internet for the steps of what to do but have been struggling. Can someone please outline the next steps for me or some thoughts as to what it could be.

It has an MSD 8202 coil without the ballast and understand the the distributor has been recurved to match the engine but am kinda still struggling to figure out what the process is.

Some pictures: https://drive.google.com/open?id=1z2GXl ... MKZL-YwVg3

Please let me know if you need more details. I have several additional black boxes (what does it do?), another Dizzy off an L16, and new plugs (what gap?).

Sorry but this is again stretching my noob knowledge.

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RMS
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Location: Richmond BC Canada

Re: Dizzy Erratic Timing

Post by RMS » 16 Jul 2018 19:32

I looked up your coil and it says with point or stock style dizzy run a ballast but I have had two of them in 6inches for years on the z24 electronic dizzy with no problems ?

when I think of erratic timing it always leads me right to the advance weight springs. pull cap and twist rotor. is there a big dead zone or are you right on the spring ?

granted I dont run fancy things like fuel injection on my engines, maybe someone has other Ideas.
two_68_510s wrote:I guess our donkeys are quicker then your sled dogs!

Beev
Posts: 10
Joined: 11 Apr 2018 13:49

Re: Dizzy Erratic Timing

Post by Beev » 16 Jul 2018 20:52

Ha I will put it back on ballast, I took it off after our discussion.

I will check the rotor thing or call you tomorrow!

Also forgot to mention it is all mechanical advance.

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D52E
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Joined: 31 Jul 2009 07:40
Location: Nashville, TN

Re: Dizzy Erratic Timing

Post by D52E » 26 Jul 2018 17:49

Is it possible to have a worn distributor shaft or bushing creating erratic timing especially at higher RPM?

Also, as previously mentioned, confirm centrifugal advance weights for springs and sticking due to corrosion.

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