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Old 11-08-2011, 10:59 PM   #121
55sedan
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Default Re: Timing retarding with locked out dist.

So looks like I have a choice of the HVC and the HVC2 to run with my box.
Any recommendations ----- one over the other????
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Old 11-08-2011, 11:23 PM   #122
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Default Re: Timing retarding with locked out dist.

i run the 2..
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Old 11-08-2011, 11:28 PM   #123
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Default Re: Timing retarding with locked out dist.

Retarding approximately 1° per 1000 RPM is normal for electronic ignitions that do not calculate the firing event from a trigger point occurring substantially before the actual spark firing moment. All electronic circuits have a time constant known as ‘slew rate’, individually unique to the particular circuit. It is the unvarying switching time from trigger input to power output.

All electronics have ‘slew rate’. The ignition system has its own lag and the timing light has its own lag and they add up. Some timing lights are slower than others, particularly lights with built in timing computers that provide “dial back” of the timing mark.

Ignitions which fire when they are triggered, that is without a processor calculating correction for engine speed and time, have no means to correct for the increased crank travel that occurs at higher RPM during the time between the trigger moment and the discharge of spark in the plug gap. The fixed slew rate and the increase in engine speed cause the spark to occur closer to TDC even when triggered at the same fixed trigger point BTDC.


If it is only retarding about 1° per 1000 RPM, consider it normal and set the timing in the RPM range where you want it to be correct.

If you can find someone who knows what they are doing with advance mechanisms and a distributor machine, the mechanical advance can be arranged to advance such that it compensates for the retard of the electronics’ slew rate


On the other hand, just having the timing retarded 6 or 8 degrees from optimum shouldn’t cause the engine to misfire if the system is healthy.
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Old 11-09-2011, 12:40 AM   #124
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Default Re: Timing retarding with locked out dist.

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Originally Posted by yeti View Post
On the other hand, just having the timing retarded 6 or 8 degrees from optimum shouldn’t cause the engine to misfire if the system is healthy.
I agree with this 100% but when I advanced timing 5* to compensate for 5* retard it never sputtered once and ran better than ever. (see post #115)
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Old 11-09-2011, 02:22 AM   #125
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Default Re: Timing retarding with locked out dist.

Just curious when you say sputter does it sound like your on and off the throttle a lil and just not happy? Also so you have a o2 sensor on it? If so what kind of readings? I think i may be in the same boat as you i rewired and moved my ignition box and btm this year and now the car shows pig rich and just dont run right its like im on and off the throttle. After reading this post i wonder if the timing retards which may show up as a rich condition. I will fix my ground etc but wont know for sure till next year now... My wiring was soooo bad before and i thought i fixed it but reading looks like i never did it right.
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Old 11-09-2011, 03:10 AM   #126
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Default Re: Timing retarding with locked out dist.

No ------------ Not like on & off throttle. No oxygen sensor.
It just sputters for a split second like it is hitting the rev limit or detonating.
You can actually see the tach needle stop climbing when it does it then start moving again. Its not a dead still stop ---- More of a bounce.
It happens 2-3 times in low and 1-2 times in high during a 1/4 mile pass.
Its not to the point that the car noses over or stops pulling, its just a very very short time.

Its not rich either -------- plugs are perfect.
It doesnt seem to be affecting performance that much. With timing set up the 5* it ran perfect, no sputtering at all
and only picked up .400s on a 500' track. Its probably worth a tenth on a 1/4 mile track.
I dont believe its detonating because Ive ran as cold as #9 plugs and timing as low as 33*. Im at #7s and timing at 41* now. (36*+5* for retard)
The lower the timing the more severe the sputtering and the harder to start.

Last edited by 55sedan; 11-09-2011 at 03:13 AM.
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Old 11-09-2011, 03:22 AM   #127
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Default Re: Timing retarding with locked out dist.

Quote:
Originally Posted by yeti View Post
Retarding approximately 1° per 1000 RPM is normal for electronic ignitions that do not calculate the firing event from a trigger point occurring substantially before the actual spark firing moment. All electronic circuits have a time constant known as ‘slew rate’, individually unique to the particular circuit. It is the unvarying switching time from trigger input to power output.

All electronics have ‘slew rate’. The ignition system has its own lag and the timing light has its own lag and they add up. Some timing lights are slower than others, particularly lights with built in timing computers that provide “dial back” of the timing mark.

Ignitions which fire when they are triggered, that is without a processor calculating correction for engine speed and time, have no means to correct for the increased crank travel that occurs at higher RPM during the time between the trigger moment and the discharge of spark in the plug gap. The fixed slew rate and the increase in engine speed cause the spark to occur closer to TDC even when triggered at the same fixed trigger point BTDC.


If it is only retarding about 1° per 1000 RPM, consider it normal and set the timing in the RPM range where you want it to be correct.

If you can find someone who knows what they are doing with advance mechanisms and a distributor machine, the mechanical advance can be arranged to advance such that it compensates for the retard of the electronics’ slew rate


On the other hand, just having the timing retarded 6 or 8 degrees from optimum shouldn’t cause the engine to misfire if the system is healthy.
Well said sir --------------- Im gonna replace the cap & rotor, double ck the pigtail wiring relationships, and I will get the correct coil.

If it still does it, I will just continue compensating for the amount of retard. At least this makes it run like its supposed to.

Will update in a few days when I get these things done. Thanks
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Old 11-09-2011, 11:57 PM   #128
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Default Re: Timing retarding with locked out dist.

wow. long post . got me intrested. my timing does the same thing as yours with a msd ready to run distributor and a digital 6 plus with a msd can style coil. my box and coil are under dash and this makes me wanna look into moving things to see if i can get it not to move. but first im going to get a new timing light than check my timing. and just to let you know my timing is locked out also with a jesel belt drive. i make my timing to read 36* when its up in r.p.m. than lock it down. hope i can figure this out.

Last edited by malibu jim; 11-09-2011 at 11:59 PM.
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Old 11-11-2011, 09:50 PM   #129
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Default Re: Timing retarding with locked out dist.

MSD problems,
I am new here, so go easy on the "flaming" I have picked up on this very interesting thread noting how many have contributed. Noting especially the ones who all have msd problems. Except for a retarding mode, would a Magneto present less problems? I have built a few BBC's for V-drives and have stuck to the magneto as a mostly trouble free ignitor.My .02
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Old 11-19-2011, 10:05 AM   #130
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Default Re: Timing retarding with locked out dist.

UPDATE

Installed the big ford style cap and a HVC blue coil.
Did away with the firewall connector for coil wire.
Coil wire is only about 6'' long now compared to about 18'' before.
Also double checked pigtail wiring relationships and they are correct.

Timing is still retarding 5*- 6* when reving but there is a very noticeable difference in the idle of the engine.
It used to idle on 1100 - 1150 rpm. Now, after these changes, the idle is up to about 1350 rpm.
It also seems more crisp and responsive when popping throttle quickly.

Im taking it to the track this afternoon, gonna run timing at 41* to compensate fo the retard.
Will post results. Hopefully the sputtering issues are over.
I believe its gonna take a crank trigger to fix the retarding issue.
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Old 11-19-2011, 11:42 AM   #131
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Default Re: Timing retarding with locked out dist.

Aint gonna lie,mine retards about 2-3 degrees when revved, I just make up for it like you are. At least it sounds crisper. Cant wait for the update at the track.
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Old 11-20-2011, 12:41 AM   #132
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Default Re: Timing retarding with locked out dist.

Good night at the track. New PB and got my 1st 9-sec pass.
Ran timing at 41* and it ran flawlessly. No sputtering what so ever.
Best pass 9.83 @ 136.2 w/1.41 60'

I want to thank everyone for all the help on this thread. Its running too good to mess with now.
I may try a crank trigger in the future, but for now Im gonna leave it alone.
Thanks again everyone.
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Old 11-20-2011, 09:52 AM   #133
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Default Re: Timing retarding with locked out dist.

what kind of fuel you running?
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Old 11-20-2011, 11:52 AM   #134
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Default Re: Timing retarding with locked out dist.

Quote:
Originally Posted by 55sedan View Post
UPDATE

Installed the big ford style cap and a HVC blue coil.
Did away with the firewall connector for coil wire.
Coil wire is only about 6'' long now compared to about 18'' before.
Also double checked pigtail wiring relationships and they are correct.

Timing is still retarding 5*- 6* when reving but there is a very noticeable difference in the idle of the engine.
It used to idle on 1100 - 1150 rpm. Now, after these changes, the idle is up to about 1350 rpm.
It also seems more crisp and responsive when popping throttle quickly.

Im taking it to the track this afternoon, gonna run timing at 41* to compensate fo the retard.
Will post results. Hopefully the sputtering issues are over.
I believe its gonna take a crank trigger to fix the retarding issue.


what part # distributor do you use and what part #cap did you switch to on the distributor. also can i ask what part # on the coil did you buy?
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Old 11-20-2011, 03:43 PM   #135
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Default Re: Timing retarding with locked out dist.

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what kind of fuel you running?
I run straight VP C12
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